EXTRUDABLE ADHESIVE COMPOSITIONS AND METHODS RELATING THERETO

Abstract: The present invention is directed to extrudable sealants which are particularly well suited for bonding a metal based, lidding material to a polystyrene container. The most preferred sealant compositions of the present invention preferably contain an acid copolymer, a tackifier and a polyolefin.

Description: EXTRUDABLE ADJIESIVE COMPOSITIONS AND METHODS RELATING THERETO Field Of The Invention. The present invention is directed to extnidable sealants which are particularly well suiled for bonding a metal based, lidding material (or tlie like) to a polyslyrelle, polypropylene or similar-type nonpolar container material, container coating material or the like. More specifically, the compositions of tlie preseilt inveiitioii preferably comprise: a) a copolymer of ethylene and a carboxylic acid or acid derivative; b) tackfier; and c) optionally, a polyolefin and/or other additives. Background Of The Invention Broadly speakiiig, extnidable seal ants are known. however, a long felt need exists iii the art for an extrudable sealant wiiicli will efficiently and effectively seal a metallized liddiiig material to a foamed polystyrene type container. Collvelllional extrudable sealaiits have been problematic due to: a) poor abhesion to metal, such as aluniinuin; b) poor heat sealability to foamed polystyrene; and/or c) in some instances, poor high temperature resistance, particularly wllen approaching I 000C. SUMMARY OF THE INVENTION Overview The exlrudable sealants of lie present invention preferrably comprise: a) a copolymer of ethylene and a carboxylic acid, particularly ethylene/acrylic acid, ethylene/methacrylic acid or combinations thereof, (alteniatively iii sonie embodiments, an acid derivative can be used in place of the acid, such as, an acid anhydride); b) a substantially nonpolar tackfier, preferrably having an acid number of less than 10, more preferably about 0; and c) optionally, a polyolefin. Conventional and non-conventional additives can also be added to the sealant compositions of the present invention. It has been surprisingly discovered that the compositions of tlie present invention are particularly well suiled as extrudable sealants for sealing metalized lidding materials to polystyrene, polypropylene or other nonpolar polyolefin or similar type conlainer material ("container material" is iiitended lo include any porlion of lie supporting structure of lie container or iii tlie alteniative can include a coating directly or indirecily supported by such supporting structure of the container) and have excellent adhesion lo metal surfaces such as aluminum foil and die like. Each of the sealant components will be discussed first, and thereafler, preferred combinations and methods of use will be described. Acid Copolymer The sealaiits of tulle preselit invention preferrably comprise at least about 20-90 weight percent ethylene/carboxylic acid copolymer, more preferably about 40%-85%, more preferably about 50%-80%, yet more preferably about 60%-75%. Preferred ethylene/acid copolymers are ethylene acrylic acid copolymer and ethylene methacrylic acid copolymer (these copolymers will hereafter be referred to collectively as "ethylene (meth)acrylic acid copolyiner"). Also, all or part of the acid functionality can be substitued with an acid derivative, such as an acid aullydride, particularly where the acid derivative provides bonding lo some extent when used in tlle final bonding application. The ethylene (meth)acrylic acid copolymers may comprise additional radical polymerizable comonomers, including grafting comonoiners. Potentially useful comonomers include, maleic anllydride, itaconic acid monomer, vinyl acetate, alplla-olefin (meth)acrylate, and the like. Preferred ethylene (meth)acrylic acid copolymers have an acrylic and/or methacrylic acid content of preferably from about 3-40% by weight, more preferably 5-30% by weight and yet more preferably 5-20% by weight. Tlle etliyleiie content is preferably in the range of about 60-95% by weight, and other comonomers are preferably in the range of about 0-25% by weight, more preferably 0-10% and most preferably 0-5%. Preferrably, the ethylene (metll)acrylic acid copolymer has a melt index in the range of about 0.5-15, more preferably 1-14. Tackifier The preferred tackifiers of the present invention have a molecular weight in the range of about 200-3000, more preferably about 500-2000. The preferred tackifiers leave softening points (ring and ball metllod) in the range of from about 50 to about 185 C, more preferably 70-1500C. The tackifier may preferably be one or more species selected from: a) coumarone-indene resins, b) plienolfonnaldehyde resins, c) polyterpene resins, d) xylenefonllaldellyde resins, e) polybutene, f) rosin pentaerytllritol ester, g) rosin glycerin ester, 11) hydrogenated rosin, i) hydrogenated rosin melllyl ester, j) hydrogenated rosin elllylene glycol ester, k) hydrogenated rosin pentaerytllrilol ester, I) polyinerized rosin ester, such as, polymerized rosin polyhydric alcohol ester (e.g., polymerized rosin peiitaerytliritol ester), m) alipllalic petroleum resin, n) alicyclic petroleum resin, o) synthetic polyterpene, pentadiene resin, etc.; and/or p) Inixtures or derivatives thereof. Particularly preferred tackifiers include fully or partially saturated tackfiers, particularly aliphatic and alicyclic. In the present invention, particularly preferred tackifiers comprise an aliphatic, alicyclic and/or aromatic llydrocarbon resin. In a preferred embodiment of the present invention, the tackfier comprises 5-40% by weight of the final sealant composition, more preferably, about 1030% and yet more preferably about 15-25% by weight. Other Optional Additives Polyolefin In a most preferred embodiment of the present i!lvention, tlle sealant further comprises a polyolefin. Preferred polyolefins are polyethylene homopolymers, polyethylene/alpha-olefin copolymers and polyethylene copolymers, polypropylene copolymers, polybutene and poly4-methyl 1pentene. If used, the applicable polyolefin comprises the following characteristics: a) melt flow rate of preferably about 0.1-50 g/10 min, (ASTM D 1238 E), more preferably about 0.3-30 and yet more preferably about 1-14 g/10 min; b) density of preferably about 0.820-0.970 g/cm3, more preferably about 0.850-0.960, and yet more preferably about 0.91-0.96 g/cm3; c) an ethylene content of about 50-100 mol %, more preferably about 75-100 inol %; and d) has a melting point (ASTM D3418) in the range of about 60 -140 C, more preferably 90 -140 C. The polyolefin can be a homopolymer or copolymer. Preferred copolymers are etliylene/alplla-olefin copolymers. Particularly useful alphaolefin coinonoiners include 3-20 carbon atoms coinonomers, such as, propylene, 1-butene, 1-hexene, 4-methy-1-pentene, 1-octene, 1-decene, 1 tetradecene, 1-octadecene, etc., and these alpha -olefins may be used either singularly or in admixtures of two or more. Particularly preferred comonomers are l-butene, 1-hexene and 1-octene. In the more preferred embodiments, the polyolefin component comprises two or more different polyolefins, preferably comprising a higher density polyolefin and optionally a lower density polyolefin. The preferred higher density polyolefin preferably has a melt index in the range of about 1-20, more preferably between 4-20 and has a density greater titan about 0.92, more preferably in tulle range of about 0.93-0.97. Tlle preferred lower density polyolefin has a density in the range of about 0.91 to about 0.93. The weight ratio of lower density polyolefin to higher density polyolefin is preferrably about 0-75: :100-25, more preferrably about 15-50: 85-50 and yet more preferably about 20-40: 80-60. Alternatively, medium density polyethylene can be substituted for this mixture ofliigli and low density polyolefin; the medium density polyethylene preferably lias a density in the range of about 0.925-0.945. Alternatively or in addition, an ethylene copolymer can also be incorporated into tlie compositions of the present invention, such as, polyethylene acrylate, polyethylene methacrylate, ethylene vinyl acetate and/or derivatives thereof. For exaniple, if ethylene vinyl acetate copolymer is used, the acetate portion of the polymer should be up to about 25% by weight, more preferably about 3-20% by weight acetate relative to the weight of the entire copolymer. All or a portion of any of tlie polyolefins of tile present invention can be graft-modified with unsaturated carboxylic acid or its derivative. If so, the polyolefin is preferrably grafted with about 0.01-15% by weight grating monomer, more preferably 0.05-15% by weight. The melt flow index is preferably 0. 1-50 g/10 min, more preferably 0.3-30 g/10 min. Suitable grafting monomers include: : a) carboxylic acids such as acrylic acid, maleic acid, filmaric acid, tetrahydrophthalic acid, itaconic acid, cilraconic acid, crotonic acid, isocrotonic acid, Nadic acid (endocis-bicyclo 12, 2, 1]liepto-5-en-2,3 dicarboxylic acid), etc. or b) derivalives tllereof, for example, acid halides, amides, imides, anliydrides, eslers, elc., such as, maleic anhydride, citraconic anhydride, monomethyl maleate, monoethyl maleate, Nadic anhydride, etc. Particularly useful grafting monomers are maleic acid or acid anhydrides thereof. Graft modification of polyethylene is well known, and can be accomplished by adding graft monomer by any conventional means known in tlle art. Other Additives Other conventional and non-conventional additives can be incorporated inlo the sealant compositions of the present invention, such as, slip additives, antiblock, chill roll release, pigments, antifog, antistat, and the like, so long as tlie addilives do not uiiduly interfere with bonding perfonnance. Tlie total amount of such other optional additives can be up to about 25% by weight of tlie final composition, more preferably ul) lo about 15% and yet more preferably up lo 10%. Additives can be added directly or through the use of a masterbatch concentrate. The Final Composition The melt flow rate of the final composition is preferably about 0.1-50 g/10 min, more preferably 0.3-30 g/10 min, more preferably 0.5-25 g/10min and yet more preferably 0.5-20 g/10 mill. The sealant resin compositions of the present invention may be prepared by combining tlle above-ineiitioned components by various known metliods, for example, by mixing these components togetller willl a llenschel mixer, vblender, ribbon blender, tumbler blender, etc., or melt kneading the resulting mixture with a single screw extruder, twin screw exlruder, kneader, Banbury mixer, etc. followed by pelletizing or melt extrusion. Upon proper melt blending or heat mixing, tlie composition can be extruded through a die and onto a substrate, such as the metal surface of an aluminum foil or other melalized lidding or packaging material or the like. The thickness of the extruded sealant is preferably about 1-100 microns, more preferably 5-60 microns. Alteniatively, tlie compositions of the present invention can be extruded into a film having a tliickness of about 1-100 microns, more preferably 5-60 microns and laminated to a metal as part of a multilayer structure. In use, tlie multilayer structure is pressed againsl a substrate surface material and heated, thereby bonding tlle mullilayer structure to the substrate; preferred substrate surface materials include polystyrene, polypropylene or other substantially non- polar polyolefin. The sealant compositions of the present invention have been found to have excellent adhesion to aluininuin foil, excellent sealability to foamed polystyrene and in some embodiments excellent temperature resistance to temperatures up to 1000C. Tlle final compositions can be used as a direct extrusion coatable resin for application directly onto aluminum foil or metalized film, such as melalized poly (ethylene lereplltllalate) (generally, there is no need for adhesives or prilners for bonding to tlle metal), and the composition can act as a heat seal layer that will heat seal a first substate surface material, such as, aluninuel to a second substrate surface material, such as, slyrene foam, polypropylene or the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) The present invention is further illustrated by the following examples. EXAMPLES Example No.1 Extrusion Coating of 1.5 mil coating of different resin Blends unto a 2 mil aluminum foil &commat; the following conditions : Melt Temperature = 459 F Line Speed =62 feet/minute Air Gap = 6 inches Table 1 EMI8.1 Resin <SEP> Melt <SEP> Density <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <tb> blend <SEP> Index <SEP> (ASTM <SEP> Olefin <SEP> Olefin <SEP> Olefin <SEP> Tack- <SEP> Acid <SEP> Acid <SEP> Acid <SEP> Acid <SEP> Ethylene <SEP> Ethylene <SEP> Acid <SEP> Acid <tb> (ASTM <SEP> D792) <SEP> Polymer <SEP> Polymer <SEP> Polymer <SEP> ifier <SEP> Co- <SEP> Co- <SEP> Co- <SEP> Ter- <SEP> Methyl <SEP> Methyl <SEP> Copoly- <SEP> Copoly D1238) <SEP> &num;1 <SEP> &num;2 <SEP> &num; ;3 <SEP> poly- <SEP> poly- <SEP> polym- <SEP> poly <SEP> Acrylate <SEP> Acrylate <SEP> mer <SEP> mer <tb> mer <SEP> mer <SEP> mer <SEP> er <SEP> mer <SEP> Copoly- <SEP> Copoly- <SEP> based <SEP> based <tb> &num;1 <SEP> &num;2 <SEP> &num;3 <SEP> mer <SEP> mer <SEP> Slip <SEP> Anti &num;1 <SEP> &num;2 <SEP> Concent- <SEP> Block <tb> rate <SEP> Concentrate <tb> (1) <SEP> (2) <SEP> (3) <SEP> (4) <SEP> (5) <SEP> (6) <SEP> (7) <SEP> (8) <SEP> (9) <SEP> (10) <SEP> (11) <SEP> (12) <tb> R-1 <SEP> 9.4 <SEP> - <SEP> 9.75 <SEP> 2.63 <SEP> 2.62 <SEP> 0 <SEP> 0 <SEP> 30 <SEP> 0 <SEP> 0 <SEP> 50 <SEP> 0 <SEP> 2 <SEP> 3 <tb> R-2 <SEP> 12 <SEP> 0.942 <SEP> 8.45 <SEP> 2.28 <SEP> 2.27 <SEP> 13 <SEP> 35 <SEP> 20 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 13 <SEP> 2.5 <SEP> 3.5 <tb> R-3 <SEP> 9 <SEP> 0.946 <SEP> 16.25 <SEP> 4.38 <SEP> 4.37 <SEP> 10 <SEP> 35 <SEP> 27.5 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 1 <SEP> 1.5 <tb> R-4 <SEP> 10.5 <SEP> 0.944 <SEP> 0 <SEP> 13 <SEP> 35 <SEP> 0 <SEP> 20 <SEP> 0 <SEP> 0 <SEP> 26 <SEP> 2.5 <SEP> 3.5 <tb> R-5 <SEP> 11.7 <SEP> 0.955 <SEP> 0 <SEP> 13 <SEP> 35 <SEP> 0 <SEP> 46 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 2.6 <SEP> 3.4 <tb> R-6 <SEP> 10 <SEP> 0.942 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 28 <SEP> 65 <SEP> 0 <SEP> 4 <SEP> 3 <tb> (1) High density polyethylene: density of 0.97 g/cc and MI of 18 g/10 min (2) Low density polyethylene: density of 0.917 g/cc and MI of 4 g/10 min (3) Low density polyethylene: density of 0.926 g/cc and MI of 8 g/10 min (4) Satruated alicyclic hydrocarbon resin with a molecular weight of 750, and Ring and Ball sofening point of 125C (5) Ethylene methacrylic acid copolymer (12% MAA, 1.5MI and 0.94 density) (6) Ethylene methacrylic acid copolymer (12% MAA, 7MI and 0.94 density) (7) Ethylene methacrylic acid copolymer (9% MAA, 10MI and 0.93 desity) (8) Ethylene methacrylic acid and isobutyl acrylate terpolymer (10% MAA, 10% iBA, 10 MI) (9) Ethylene methyl acrylate copolymer (20% MA, 6MI and 0.942 density) (10) Ethylene methyl acrylate copolymer (6.5% MA, 6MI and 0.922 density) (11) 80% of ethylene metharylic acid copolymer with 9% methacrylic acid and 10 MI plus 20% stearamide (12) 87.5% of ethylene metharylic acid copolymer with 9% methacrylic acid and 10 MI plus 12.5% of silica Table 2 EMI9.1 Resin <SEP> blend/foil <SEP> Adhesion <SEP> to <SEP> Heat <SEP> Seal <SEP> to <SEP> PS <SEP> PAFT <SEP> (C) <tb> 1.5 <SEP> mil/2 <SEP> mil) <SEP> Aluminum <SEP> Foam <tb> (g/inch) <SEP> (g/inch) <tb> ASTM <SEP> &commat; <SEP> 250-300-350 <SEP> (F) <tb> A630.0030 <tb> R-1/foil <SEP> 11 <SEP> 379-557-789 <SEP> 64 <tb> R-2/foil <SEP> 439 <SEP> 519-501-729 <SEP> 108 <tb> R-3/foil <SEP> 265 <SEP> 305-556-620 <SEP> 109 <tb> R-4/foil <SEP> 415 <SEP> 389-602-785 <SEP> 109 <tb> R-5/foil <SEP> 427 <SEP> 449-673-835 <SEP> 106 <tb> R-6/foil <SEP> 7 <SEP> 542-642-879 <SEP> 42 <tb> Table 3 EMI10.1 Resin <SEP> Melt <SEP> Density <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <SEP> % <tb> Blend <SEP> Index <SEP> ASTM <SEP> Olefin <SEP> Olefin <SEP> Olefin <SEP> Olefin <SEP> Tacki- <SEP> Acid <SEP> Acid <SEP> Ethylene <SEP> Acid <SEP> Acid <tb> ASTM <SEP> D792 <SEP> Polymer <SEP> Polymer <SEP> Polymer <SEP> Polymer <SEP> fier <SEP> Copoly <SEP> Copoly <SEP> Acrylate <SEP> Copolymer <SEP> Copolymer <tb> D1238 <SEP> &num;1 <SEP> &num;2 <SEP> &num;3 <SEP> &num; ;4 <SEP> mer <SEP> mer <SEP> Copoly- <SEP> Based <SEP> Slip <SEP> Based <SEP> Anti &num;1 <SEP> &num;2 <SEP> mer <SEP> Concentrate <SEP> block <tb> Concnetrate <tb> (1) <SEP> (2) <SEP> (3) <SEP> (4) <SEP> (5) <SEP> (6) <SEP> (7) <SEP> (8) <SEP> (9) <SEP> (10) <tb> LC1 <SEP> 11.2 <SEP> 0.946 <SEP> 16.25 <SEP> 4.38 <SEP> 4.37 <SEP> 0 <SEP> 17 <SEP> 40 <SEP> 13 <SEP> 0 <SEP> 2.5 <SEP> 2.5 <tb> LC2 <SEP> 11.9 <SEP> 0.944 <SEP> 13 <SEP> 3.5 <SEP> 3.5 <SEP> 0 <SEP> 17 <SEP> 40 <SEP> 18 <SEP> 0 <SEP> 2.5 <SEP> 2.5 <tb> LC3 <SEP> 11.0 <SEP> 0.948 <SEP> 9.75 <SEP> 2.63 <SEP> 2.62 <SEP> 0 <SEP> 17 <SEP> 40 <SEP> 23 <SEP> 0 <SEP> 2.5 <SEP> 2.5 <tb> LC4 <SEP> 11.9 <SEP> 0.942 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 20 <SEP> 17 <SEP> 40 <SEP> 18 <SEP> 0 <SEP> 2.5 <SEP> 2.5 <tb> LC5 <SEP> 12.2 <SEP> 0.943 <SEP> 11.7 <SEP> 3.15 <SEP> 3.15 <SEP> 0 <SEP> 17 <SEP> 40 <SEP> 0 <SEP> 20 <SEP> 2.5 <SEP> 2.5 <tb> (1) High density polyethylene: density of 0.97 g/cc and MI of 18 g/10 min (2) Low density polyethylene: density of 0.917 g/cc and MI of 4 g/10 min (3) Low density polyethylene: density of 0.926 g/cc and MI of 8 g/10 min (4) Medium density polyethylene: density of 0.93 g/cc and MI of 6.8 g/10 min (5) Satruated alicyclic hydrocarbon resin with a molecular weight of 750, and Ring and Ball sofening point of 125C (6) Ethylene methacrylic acid copolymer (12% MAA, 1.5MI and 0.94 density) (7) Ethylene methacrylic acid copolymer (12% MAA, 7MI and 0.94 density) (8) Ethylene methyl acrylate copoly mer (6.5% MA, 6 MI and 0.922 density) (9) 80% of ethylene metharylic acid copolymer with 9% methacrylic acid and 10 MI plus 20% stearamide (10) 87.5% of ethylene metharylic acid copolymer with 9% methyacrylic acid and 10 MI plus 12.5% of silica Table 4 EMI11.1 Resin <SEP> Blend/foil <SEP> Foil <SEP> adhesion <SEP> Heat <SEP> Seal <SEP> to <SEP> PS <SEP> PAFT <SEP> (C) <tb> (1.3 <SEP> mil/2 <SEP> mil) <SEP> (g/inch) <SEP> foam <SEP> (g/inch) <tb> ASTM-A630.0030 <SEP> &commat; <SEP> 250-300-350 <SEP> (F) <tb> LC1/foil-paper <SEP> laminate <SEP> 263 <SEP> 82-164-204 <SEP> LC2/foil-paper <SEP> laminate <SEP> 1071 <SEP> 88-149-189 <SEP> 108 <tb> LC3/foil-paper <SEP> laminate <SEP> 871 <SEP> 136-230-314 <SEP> 107 <tb> LC4/foil-paper <SEP> laminate <SEP> 385 <SEP> 119-305-436 <SEP> LC5/foil-paper <SEP> laminate <SEP> 124 <SEP> 125-320-390 <SEP>

Claims: WHAT 1S CLAIMED IS: 1. A thermoplastic sealant composition comprising: a) a random polyinerized, unneutralized, acid copolymer having an acid contellt of frolli about 5 to about 20 percent by weight; and b) a substantially nonpolar tackfier having all acid nurnber of about 0; wherein: i. tlie weight ratio of a:b is in tile range of about 20-90: 10-80; ii. the finial sealant compositioll is substantially free of halogen, cation, epoxy or silane moieties; and iii. tile filial sealant composition defines a melt index in the range of about 0.3-30 g/10 mill (ASTM D 1238 E). 2. A composition in accordance with Claim 1 wherein a) is an ethylene acrylic acid copolymer or an ethylene methacrylic acid copolymer. 3. A composition in accordance with Claim 2 further comprising 3%- 40% by weight (based upon the weight of the final composition) polyolefin having the following characteristics: a) melt flow rate of about 0.3-30 g/10 min (ASTM D 1238 E); b) a density of about 0.820-0.960 g/cm3; c) an ethylene content of about 50-96 mol %; and d) a melling point (ASTM D3418) in the range of about 60 -140 C. 4. A composition in accordance with Claim 3 wherein the polyolefin component further comprises: A. a polyolefin having a melt index in the range of about 1-20, and a density in the range of about 0.93-0.97; and B. a polyolefin having a density of from about 0.91 to about 0.93, wherein the ratio of A:B is in the range of about 40-90: 10-60. 5. A composition in accordance with Claim 3 wherein the polyolefin component is a medium density polyolefin having a density in the range of about 0.925 to about 0.945. 6. A composition in accordance with claim 6 wherein tile tackifier lias a molecular weight in the range of about 500-2000, a softening point (rillg and ball method) in the range of from about 70 C lo about 1500C. 7. A package comprising: a foamed polystyrene container; a lidding film comprising a metalized layer; and a thermoplastic sealant adhered to the lidding structure which bonds or seals die liddiiig filiu to tlie container, the sealant comprising: a) a random polymerized, unneutralized, acid copolymer having an acid content of from about 5 to about 20 percent by weight; and b) a substantially nonpolar tackfier having an acid number of about 0; wherein: i. the weight ratio of a:b is in the range of about 40-90: 10-60; ii. tlie final sealant composition is substantially free of halogen, cation. epoxy or silane moieties; and iii. tlie final sealant composition defines a melt index in the range of about 0.3-30 g/10 min (ASTM D 1238 E). AMENDED CLAIMS [received by the International Bureau on 29 August 1995 (29.08.95); original claim 1 amended; remaining claims unchanged (2 pages)] 1. A thermoplastic sealant composition comprising: a) a random polymerized, unneutralized, acid copolymer having an acid content of from 5 to 20 percent by weight; and b) a substantially non polar hydrocarbon tackifier having an acid number of 0; wherein: i. the weight ratio of a:b is in the range of 20-90:80-101 ii. the final sealant composition is substantially free of halogen, cation, epoxy or silane moieties; and iii. the final sealant composition defines a melt index in the range of about 0.3-30 g/10 min (ASTM D 1238 E). 2. A composition in accordance with claim 1 wherein a) is an ethylene acrylic acid copolymer or an ethylene methacrylic acid copolymer. 3. A composition in accordance with claim 2 further comprising 3%-40% by weight (based upon the weight of the final composition) polyolefin having the following characteristics: a) melt flow rate of 0.3-30 g/10 min (ASTM D 1238 E); b) a density of 0.820-0.960 g/cm3; c) an ethylene content of 50-96 mol ; and d) a melting point (ASTM D3418) in the range of 600C-1400C. 4. A composition in accordance with claim 3 wherein the polyolefin component further comprises: A. a polyolefin having a melt index in the range of 1-20, and a density in the range of 0.93 g/cm3-0.97 g/cm3, and B. a polyolefin having a density of from 0.91 g/cm3 to 0.93 g/cm3, wherein the ratio of A:B is in the range of 40-90:60-10. 5. A composition in accordance with claim 3 wherein the polyolefin component is a medium density polyolefin having a density in the range of 0.925 to 0.945. 6. A composition in accordance with claim 6 wherein the tackifier has a molecular weight in the range of 500-2000, a softening point (ring and ball method) in the range of from 700C to 1500C. 7. A package comprising: a foamed polystyrene container; a lidding film comprising a metallized layer; and a thermoplastic sealant adhered to the lidding structure which bonds or seals the lidding film to the container, the sealant comprising: a) a random polymerized, unneutralized, acid copolymer having an acid content of from 5 to 20 percent by weight; and b) a substantially non polar tackifier having an acid number of 0; wherein: i. the weight ratio of a:b is in the range of 40-90:10-60; ii. the final sealant composition is substantially free of halogen, cation, epoxy or silane moieties; and iii. the final sealant composition defines a melt index in the range of 0.3-30 g/10 min (ASTM D 1238 E).

Inventors: ANTONOV VLADIMIR, SOUTAR ALISTER MICHAEL, TANNY STEPHEN ROBERT, ZHANG DAVID DAWEI, ANTONOV, VLADIMIR, SOUTAR, ALISTER, MICHAEL, TANNY, STEPHEN, ROBERT, ZHANG, DAVID, DAWEI
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1995
Main classification: C09J123
IPC codes: B65D77, C09J123, C09K3