CA3011044A1 - Acid resistant polyethylene containers - Google Patents
Acid resistant polyethylene containers Download PDFInfo
- Publication number
- CA3011044A1 CA3011044A1 CA3011044A CA3011044A CA3011044A1 CA 3011044 A1 CA3011044 A1 CA 3011044A1 CA 3011044 A CA3011044 A CA 3011044A CA 3011044 A CA3011044 A CA 3011044A CA 3011044 A1 CA3011044 A1 CA 3011044A1
- Authority
- CA
- Canada
- Prior art keywords
- ethylene copolymer
- copolymer composition
- ppm
- primary antioxidant
- antioxidant
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- -1 polyethylene Polymers 0.000 title claims abstract description 35
- 239000004698 Polyethylene Substances 0.000 title claims abstract description 22
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 22
- 239000002253 acid Substances 0.000 title claims abstract description 13
- 239000003963 antioxidant agent Substances 0.000 claims abstract description 39
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000000654 additive Substances 0.000 claims abstract description 23
- 230000000996 additive effect Effects 0.000 claims abstract description 17
- 239000000203 mixture Substances 0.000 claims description 44
- 229920001038 ethylene copolymer Polymers 0.000 claims description 31
- 230000003078 antioxidant effect Effects 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 21
- 238000001175 rotational moulding Methods 0.000 claims description 20
- 150000001412 amines Chemical class 0.000 claims description 15
- 239000003054 catalyst Substances 0.000 claims description 15
- AVXURJPOCDRRFD-UHFFFAOYSA-N Hydroxylamine Chemical compound ON AVXURJPOCDRRFD-UHFFFAOYSA-N 0.000 claims description 14
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims description 11
- 239000004611 light stabiliser Substances 0.000 claims description 10
- 238000000465 moulding Methods 0.000 claims description 10
- 238000002845 discoloration Methods 0.000 claims description 8
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 claims description 7
- 239000000155 melt Substances 0.000 claims description 4
- 229920001577 copolymer Polymers 0.000 description 38
- 238000009826 distribution Methods 0.000 description 15
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 14
- 229920003023 plastic Polymers 0.000 description 10
- 239000004033 plastic Substances 0.000 description 10
- 238000002474 experimental method Methods 0.000 description 8
- 229920001519 homopolymer Polymers 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 229920000642 polymer Polymers 0.000 description 7
- 239000011787 zinc oxide Substances 0.000 description 7
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 6
- 239000005977 Ethylene Substances 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 230000000704 physical effect Effects 0.000 description 6
- 235000013824 polyphenols Nutrition 0.000 description 6
- 102100029464 Aquaporin-9 Human genes 0.000 description 5
- 101000771413 Homo sapiens Aquaporin-9 Proteins 0.000 description 5
- 101000921370 Homo sapiens Elongation of very long chain fatty acids protein 1 Proteins 0.000 description 5
- 239000004711 α-olefin Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 150000002148 esters Chemical class 0.000 description 4
- VNQNXQYZMPJLQX-UHFFFAOYSA-N 1,3,5-tris[(3,5-ditert-butyl-4-hydroxyphenyl)methyl]-1,3,5-triazinane-2,4,6-trione Chemical compound CC(C)(C)C1=C(O)C(C(C)(C)C)=CC(CN2C(N(CC=3C=C(C(O)=C(C=3)C(C)(C)C)C(C)(C)C)C(=O)N(CC=3C=C(C(O)=C(C=3)C(C)(C)C)C(C)(C)C)C2=O)=O)=C1 VNQNXQYZMPJLQX-UHFFFAOYSA-N 0.000 description 3
- JKIJEFPNVSHHEI-UHFFFAOYSA-N Phenol, 2,4-bis(1,1-dimethylethyl)-, phosphite (3:1) Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC=C1OP(OC=1C(=CC(=CC=1)C(C)(C)C)C(C)(C)C)OC1=CC=C(C(C)(C)C)C=C1C(C)(C)C JKIJEFPNVSHHEI-UHFFFAOYSA-N 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- ITUWQZXQRZLLCR-UHFFFAOYSA-N n,n-dioctadecylhydroxylamine Chemical compound CCCCCCCCCCCCCCCCCCN(O)CCCCCCCCCCCCCCCCCC ITUWQZXQRZLLCR-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 150000002989 phenols Chemical class 0.000 description 3
- 229940116351 sebacate Drugs 0.000 description 3
- 239000003381 stabilizer Substances 0.000 description 3
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- BJELTSYBAHKXRW-UHFFFAOYSA-N 2,4,6-triallyloxy-1,3,5-triazine Chemical compound C=CCOC1=NC(OCC=C)=NC(OCC=C)=N1 BJELTSYBAHKXRW-UHFFFAOYSA-N 0.000 description 2
- BVUXDWXKPROUDO-UHFFFAOYSA-N 2,6-di-tert-butyl-4-ethylphenol Chemical compound CCC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 BVUXDWXKPROUDO-UHFFFAOYSA-N 0.000 description 2
- JLZIIHMTTRXXIN-UHFFFAOYSA-N 2-(2-hydroxy-4-methoxybenzoyl)benzoic acid Chemical compound OC1=CC(OC)=CC=C1C(=O)C1=CC=CC=C1C(O)=O JLZIIHMTTRXXIN-UHFFFAOYSA-N 0.000 description 2
- SWZOQAGVRGQLDV-UHFFFAOYSA-N 4-[2-(4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yl)ethoxy]-4-oxobutanoic acid Chemical compound CC1(C)CC(O)CC(C)(C)N1CCOC(=O)CCC(O)=O SWZOQAGVRGQLDV-UHFFFAOYSA-N 0.000 description 2
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 239000001273 butane Substances 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 239000007859 condensation product Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000007334 copolymerization reaction Methods 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- ZJIPHXXDPROMEF-UHFFFAOYSA-N dihydroxyphosphanyl dihydrogen phosphite Chemical compound OP(O)OP(O)O ZJIPHXXDPROMEF-UHFFFAOYSA-N 0.000 description 2
- 230000006353 environmental stress Effects 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 150000002443 hydroxylamines Chemical class 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- ORECYURYFJYPKY-UHFFFAOYSA-N n,n'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexane-1,6-diamine;2,4,6-trichloro-1,3,5-triazine;2,4,4-trimethylpentan-2-amine Chemical compound CC(C)(C)CC(C)(C)N.ClC1=NC(Cl)=NC(Cl)=N1.C1C(C)(C)NC(C)(C)CC1NCCCCCCNC1CC(C)(C)NC(C)(C)C1 ORECYURYFJYPKY-UHFFFAOYSA-N 0.000 description 2
- GXELTROTKVKZBQ-UHFFFAOYSA-N n,n-dibenzylhydroxylamine Chemical compound C=1C=CC=CC=1CN(O)CC1=CC=CC=C1 GXELTROTKVKZBQ-UHFFFAOYSA-N 0.000 description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- 239000002667 nucleating agent Substances 0.000 description 2
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 2
- NFHFRUOZVGFOOS-UHFFFAOYSA-N palladium;triphenylphosphane Chemical compound [Pd].C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 NFHFRUOZVGFOOS-UHFFFAOYSA-N 0.000 description 2
- 150000002978 peroxides Chemical class 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- XRBCRPZXSCBRTK-UHFFFAOYSA-N phosphonous acid Chemical compound OPO XRBCRPZXSCBRTK-UHFFFAOYSA-N 0.000 description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 2
- 150000003018 phosphorus compounds Chemical class 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 239000000600 sorbitol Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- HVLLSGMXQDNUAL-UHFFFAOYSA-N triphenyl phosphite Chemical compound C=1C=CC=CC=1OP(OC=1C=CC=CC=1)OC1=CC=CC=C1 HVLLSGMXQDNUAL-UHFFFAOYSA-N 0.000 description 2
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 2
- YAXWOADCWUUUNX-UHFFFAOYSA-N 1,2,2,3-tetramethylpiperidine Chemical group CC1CCCN(C)C1(C)C YAXWOADCWUUUNX-UHFFFAOYSA-N 0.000 description 1
- KOMNUTZXSVSERR-UHFFFAOYSA-N 1,3,5-tris(prop-2-enyl)-1,3,5-triazinane-2,4,6-trione Chemical compound C=CCN1C(=O)N(CC=C)C(=O)N(CC=C)C1=O KOMNUTZXSVSERR-UHFFFAOYSA-N 0.000 description 1
- NOSXUFXBUISMPR-UHFFFAOYSA-N 1-tert-butylperoxyhexane Chemical compound CCCCCCOOC(C)(C)C NOSXUFXBUISMPR-UHFFFAOYSA-N 0.000 description 1
- RKMGAJGJIURJSJ-UHFFFAOYSA-N 2,2,6,6-Tetramethylpiperidine Substances CC1(C)CCCC(C)(C)N1 RKMGAJGJIURJSJ-UHFFFAOYSA-N 0.000 description 1
- MXSKJYLPNPYQHH-UHFFFAOYSA-N 2,4-dimethyl-6-(1-methylcyclohexyl)phenol Chemical compound CC1=CC(C)=C(O)C(C2(C)CCCCC2)=C1 MXSKJYLPNPYQHH-UHFFFAOYSA-N 0.000 description 1
- OPLCSTZDXXUYDU-UHFFFAOYSA-N 2,4-dimethyl-6-tert-butylphenol Chemical compound CC1=CC(C)=C(O)C(C(C)(C)C)=C1 OPLCSTZDXXUYDU-UHFFFAOYSA-N 0.000 description 1
- LXWZXEJDKYWBOW-UHFFFAOYSA-N 2,4-ditert-butyl-6-[(3,5-ditert-butyl-2-hydroxyphenyl)methyl]phenol Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC(CC=2C(=C(C=C(C=2)C(C)(C)C)C(C)(C)C)O)=C1O LXWZXEJDKYWBOW-UHFFFAOYSA-N 0.000 description 1
- CZNRFEXEPBITDS-UHFFFAOYSA-N 2,5-bis(2-methylbutan-2-yl)benzene-1,4-diol Chemical compound CCC(C)(C)C1=CC(O)=C(C(C)(C)CC)C=C1O CZNRFEXEPBITDS-UHFFFAOYSA-N 0.000 description 1
- JZODKRWQWUWGCD-UHFFFAOYSA-N 2,5-di-tert-butylbenzene-1,4-diol Chemical compound CC(C)(C)C1=CC(O)=C(C(C)(C)C)C=C1O JZODKRWQWUWGCD-UHFFFAOYSA-N 0.000 description 1
- SLUKQUGVTITNSY-UHFFFAOYSA-N 2,6-di-tert-butyl-4-methoxyphenol Chemical compound COC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 SLUKQUGVTITNSY-UHFFFAOYSA-N 0.000 description 1
- LBOGPIWNHXHYHN-UHFFFAOYSA-N 2-(2-hydroxy-5-octylphenyl)sulfanyl-4-octylphenol Chemical compound CCCCCCCCC1=CC=C(O)C(SC=2C(=CC=C(CCCCCCCC)C=2)O)=C1 LBOGPIWNHXHYHN-UHFFFAOYSA-N 0.000 description 1
- BVNPSIYFJSSEER-UHFFFAOYSA-H 2-[2-(1,3,2-benzodioxastibol-2-yloxy)phenoxy]-1,3,2-benzodioxastibole Chemical compound O([Sb]1Oc2ccccc2O1)c1ccccc1O[Sb]1Oc2ccccc2O1 BVNPSIYFJSSEER-UHFFFAOYSA-H 0.000 description 1
- WBJWXIQDBDZMAW-UHFFFAOYSA-N 2-hydroxynaphthalene-1-carbonyl chloride Chemical compound C1=CC=CC2=C(C(Cl)=O)C(O)=CC=C21 WBJWXIQDBDZMAW-UHFFFAOYSA-N 0.000 description 1
- RKLRVTKRKFEVQG-UHFFFAOYSA-N 2-tert-butyl-4-[(3-tert-butyl-4-hydroxy-5-methylphenyl)methyl]-6-methylphenol Chemical compound CC(C)(C)C1=C(O)C(C)=CC(CC=2C=C(C(O)=C(C)C=2)C(C)(C)C)=C1 RKLRVTKRKFEVQG-UHFFFAOYSA-N 0.000 description 1
- AIBRSVLEQRWAEG-UHFFFAOYSA-N 3,9-bis(2,4-ditert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC=C1OP1OCC2(COP(OC=3C(=CC(=CC=3)C(C)(C)C)C(C)(C)C)OC2)CO1 AIBRSVLEQRWAEG-UHFFFAOYSA-N 0.000 description 1
- YLUZWKKWWSCRSR-UHFFFAOYSA-N 3,9-bis(8-methylnonoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane Chemical compound C1OP(OCCCCCCCC(C)C)OCC21COP(OCCCCCCCC(C)C)OC2 YLUZWKKWWSCRSR-UHFFFAOYSA-N 0.000 description 1
- WBWXVCMXGYSMQA-UHFFFAOYSA-N 3,9-bis[2,4-bis(2-phenylpropan-2-yl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane Chemical compound C=1C=C(OP2OCC3(CO2)COP(OC=2C(=CC(=CC=2)C(C)(C)C=2C=CC=CC=2)C(C)(C)C=2C=CC=CC=2)OC3)C(C(C)(C)C=2C=CC=CC=2)=CC=1C(C)(C)C1=CC=CC=C1 WBWXVCMXGYSMQA-UHFFFAOYSA-N 0.000 description 1
- PZRWFKGUFWPFID-UHFFFAOYSA-N 3,9-dioctadecoxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane Chemical compound C1OP(OCCCCCCCCCCCCCCCCCC)OCC21COP(OCCCCCCCCCCCCCCCCCC)OC2 PZRWFKGUFWPFID-UHFFFAOYSA-N 0.000 description 1
- VPWNQTHUCYMVMZ-UHFFFAOYSA-N 4,4'-sulfonyldiphenol Chemical class C1=CC(O)=CC=C1S(=O)(=O)C1=CC=C(O)C=C1 VPWNQTHUCYMVMZ-UHFFFAOYSA-N 0.000 description 1
- WTWGHNZAQVTLSQ-UHFFFAOYSA-N 4-butyl-2,6-ditert-butylphenol Chemical compound CCCCC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 WTWGHNZAQVTLSQ-UHFFFAOYSA-N 0.000 description 1
- KDVYCTOWXSLNNI-UHFFFAOYSA-N 4-t-Butylbenzoic acid Chemical compound CC(C)(C)C1=CC=C(C(O)=O)C=C1 KDVYCTOWXSLNNI-UHFFFAOYSA-N 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 229930185605 Bisphenol Natural products 0.000 description 1
- 239000004604 Blowing Agent Substances 0.000 description 1
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 1
- ZRZFCHCIMYNMST-UHFFFAOYSA-L C=1([O-])C([O-])=CC=CC1.[Zn+2] Chemical compound C=1([O-])C([O-])=CC=CC1.[Zn+2] ZRZFCHCIMYNMST-UHFFFAOYSA-L 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229920001174 Diethylhydroxylamine Polymers 0.000 description 1
- 239000002656 Distearyl thiodipropionate Substances 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 239000004594 Masterbatch (MB) Substances 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- REYJJPSVUYRZGE-UHFFFAOYSA-N Octadecylamine Chemical compound CCCCCCCCCCCCCCCCCCN REYJJPSVUYRZGE-UHFFFAOYSA-N 0.000 description 1
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 1
- 229920000535 Tan II Polymers 0.000 description 1
- 239000007983 Tris buffer Substances 0.000 description 1
- 239000011954 Ziegler–Natta catalyst Substances 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 1
- 239000001361 adipic acid Substances 0.000 description 1
- 235000011037 adipic acid Nutrition 0.000 description 1
- OFHCOWSQAMBJIW-AVJTYSNKSA-N alfacalcidol Chemical compound C1(/[C@@H]2CC[C@@H]([C@]2(CCC1)C)[C@H](C)CCCC(C)C)=C\C=C1\C[C@@H](O)C[C@H](O)C1=C OFHCOWSQAMBJIW-AVJTYSNKSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- PYHXGXCGESYPCW-UHFFFAOYSA-N alpha-phenylbenzeneacetic acid Natural products C=1C=CC=CC=1C(C(=O)O)C1=CC=CC=C1 PYHXGXCGESYPCW-UHFFFAOYSA-N 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- GUDSEWUOWPVZPC-UHFFFAOYSA-N bis(2,4-ditert-butylphenyl) hydrogen phosphate Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC=C1OP(O)(=O)OC1=CC=C(C(C)(C)C)C=C1C(C)(C)C GUDSEWUOWPVZPC-UHFFFAOYSA-N 0.000 description 1
- 235000010354 butylated hydroxytoluene Nutrition 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- MKJXYGKVIBWPFZ-UHFFFAOYSA-L calcium lactate Chemical compound [Ca+2].CC(O)C([O-])=O.CC(O)C([O-])=O MKJXYGKVIBWPFZ-UHFFFAOYSA-L 0.000 description 1
- 239000001527 calcium lactate Substances 0.000 description 1
- 229960002401 calcium lactate Drugs 0.000 description 1
- 235000011086 calcium lactate Nutrition 0.000 description 1
- OEUVSBXAMBLPES-UHFFFAOYSA-L calcium stearoyl-2-lactylate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC(=O)OC(C)C(=O)OC(C)C([O-])=O.CCCCCCCCCCCCCCCCCC(=O)OC(C)C(=O)OC(C)C([O-])=O OEUVSBXAMBLPES-UHFFFAOYSA-L 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- MMCOUVMKNAHQOY-UHFFFAOYSA-N carbonoperoxoic acid Chemical class OOC(O)=O MMCOUVMKNAHQOY-UHFFFAOYSA-N 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- FVCOIAYSJZGECG-UHFFFAOYSA-N diethylhydroxylamine Chemical compound CCN(O)CC FVCOIAYSJZGECG-UHFFFAOYSA-N 0.000 description 1
- PWWSSIYVTQUJQQ-UHFFFAOYSA-N distearyl thiodipropionate Chemical compound CCCCCCCCCCCCCCCCCCOC(=O)CCSCCC(=O)OCCCCCCCCCCCCCCCCCC PWWSSIYVTQUJQQ-UHFFFAOYSA-N 0.000 description 1
- 235000019305 distearyl thiodipropionate Nutrition 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 239000012632 extractable Substances 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- IPCSVZSSVZVIGE-UHFFFAOYSA-M hexadecanoate Chemical compound CCCCCCCCCCCCCCCC([O-])=O IPCSVZSSVZVIGE-UHFFFAOYSA-M 0.000 description 1
- 150000002429 hydrazines Chemical class 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- QLNAVQRIWDRPHA-UHFFFAOYSA-N iminophosphane Chemical compound P=N QLNAVQRIWDRPHA-UHFFFAOYSA-N 0.000 description 1
- 150000004694 iodide salts Chemical class 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 125000000325 methylidene group Chemical group [H]C([H])=* 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- DDLNUIWJEDITCB-UHFFFAOYSA-N n,n-di(tetradecyl)hydroxylamine Chemical compound CCCCCCCCCCCCCCN(O)CCCCCCCCCCCCCC DDLNUIWJEDITCB-UHFFFAOYSA-N 0.000 description 1
- DHXOCDLHWYUUAG-UHFFFAOYSA-N n,n-didodecylhydroxylamine Chemical compound CCCCCCCCCCCCN(O)CCCCCCCCCCCC DHXOCDLHWYUUAG-UHFFFAOYSA-N 0.000 description 1
- OTXXCIYKATWWQI-UHFFFAOYSA-N n,n-dihexadecylhydroxylamine Chemical compound CCCCCCCCCCCCCCCCN(O)CCCCCCCCCCCCCCCC OTXXCIYKATWWQI-UHFFFAOYSA-N 0.000 description 1
- WQAJFRSBFZAUPB-UHFFFAOYSA-N n,n-dioctylhydroxylamine Chemical compound CCCCCCCCN(O)CCCCCCCC WQAJFRSBFZAUPB-UHFFFAOYSA-N 0.000 description 1
- ZRPOKHXBOZQSOX-UHFFFAOYSA-N n-heptadecyl-n-octadecylhydroxylamine Chemical compound CCCCCCCCCCCCCCCCCCN(O)CCCCCCCCCCCCCCCCC ZRPOKHXBOZQSOX-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- SSDSCDGVMJFTEQ-UHFFFAOYSA-N octadecyl 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical compound CCCCCCCCCCCCCCCCCCOC(=O)CCC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 SSDSCDGVMJFTEQ-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000012934 organic peroxide initiator Substances 0.000 description 1
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 description 1
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 1
- AQSJGOWTSHOLKH-UHFFFAOYSA-N phosphite(3-) Chemical class [O-]P([O-])[O-] AQSJGOWTSHOLKH-UHFFFAOYSA-N 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 1
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 1
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 239000012744 reinforcing agent Substances 0.000 description 1
- WBHHMMIMDMUBKC-QJWNTBNXSA-M ricinoleate Chemical compound CCCCCC[C@@H](O)C\C=C/CCCCCCCC([O-])=O WBHHMMIMDMUBKC-QJWNTBNXSA-M 0.000 description 1
- 229940066675 ricinoleate Drugs 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- CXMXRPHRNRROMY-UHFFFAOYSA-L sebacate(2-) Chemical compound [O-]C(=O)CCCCCCCCC([O-])=O CXMXRPHRNRROMY-UHFFFAOYSA-L 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- RPACBEVZENYWOL-XFULWGLBSA-M sodium;(2r)-2-[6-(4-chlorophenoxy)hexyl]oxirane-2-carboxylate Chemical compound [Na+].C=1C=C(Cl)C=CC=1OCCCCCC[C@]1(C(=O)[O-])CO1 RPACBEVZENYWOL-XFULWGLBSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 235000012424 soybean oil Nutrition 0.000 description 1
- 239000003549 soybean oil Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000001384 succinic acid Substances 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- KKEYFWRCBNTPAC-UHFFFAOYSA-L terephthalate(2-) Chemical compound [O-]C(=O)C1=CC=C(C([O-])=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-L 0.000 description 1
- 229920001897 terpolymer Polymers 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- IVIIAEVMQHEPAY-UHFFFAOYSA-N tridodecyl phosphite Chemical compound CCCCCCCCCCCCOP(OCCCCCCCCCCCC)OCCCCCCCCCCCC IVIIAEVMQHEPAY-UHFFFAOYSA-N 0.000 description 1
- CNUJLMSKURPSHE-UHFFFAOYSA-N trioctadecyl phosphite Chemical compound CCCCCCCCCCCCCCCCCCOP(OCCCCCCCCCCCCCCCCCC)OCCCCCCCCCCCCCCCCCC CNUJLMSKURPSHE-UHFFFAOYSA-N 0.000 description 1
- WGKLOLBTFWFKOD-UHFFFAOYSA-N tris(2-nonylphenyl) phosphite Chemical compound CCCCCCCCCC1=CC=CC=C1OP(OC=1C(=CC=CC=1)CCCCCCCCC)OC1=CC=CC=C1CCCCCCCCC WGKLOLBTFWFKOD-UHFFFAOYSA-N 0.000 description 1
- GRPURDFRFHUDSP-UHFFFAOYSA-N tris(prop-2-enyl) benzene-1,2,4-tricarboxylate Chemical compound C=CCOC(=O)C1=CC=C(C(=O)OCC=C)C(C(=O)OCC=C)=C1 GRPURDFRFHUDSP-UHFFFAOYSA-N 0.000 description 1
- 150000003672 ureas Chemical class 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 235000015112 vegetable and seed oil Nutrition 0.000 description 1
- 239000008158 vegetable oil Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/04—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/003—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor characterised by the choice of material
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
- C08K5/005—Stabilisers against oxidation, heat, light, ozone
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/13—Phenols; Phenolates
- C08K5/134—Phenols containing ester groups
- C08K5/1345—Carboxylic esters of phenolcarboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
- C08K5/32—Compounds containing nitrogen bound to oxygen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
- C08K5/34—Heterocyclic compounds having nitrogen in the ring
- C08K5/3412—Heterocyclic compounds having nitrogen in the ring having one nitrogen atom in the ring
- C08K5/3432—Six-membered rings
- C08K5/3435—Piperidines
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
- C08K5/34—Heterocyclic compounds having nitrogen in the ring
- C08K5/3467—Heterocyclic compounds having nitrogen in the ring having more than two nitrogen atoms in the ring
- C08K5/3477—Six-membered rings
- C08K5/3492—Triazines
- C08K5/34926—Triazines also containing heterocyclic groups other than triazine groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/49—Phosphorus-containing compounds
- C08K5/51—Phosphorus bound to oxygen
- C08K5/52—Phosphorus bound to oxygen only
- C08K5/524—Esters of phosphorous acids, e.g. of H3PO3
- C08K5/526—Esters of phosphorous acids, e.g. of H3PO3 with hydroxyaryl compounds
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Anti-Oxidant Or Stabilizer Compositions (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
Rotomolded polyethylene containers that are used to store sulfuric acid can become discolored on the interior surface which is in contact with the acid. This problem is mitigated by the use of an additive package that contains two primary antioxidants.
Description
ACID RESISTANT POLYETHYLENE CONTAINERS
FIELD OF THE INVENTION
This invention provides a rotomolded polyethylene container that is resistant to discoloration when contacted with sulfuric acid.
BACKGROUND OF THE INVENTION
Rotational molding, also known as rotomolding, is a well known process which is widely used to produce hollow plastic parts such as gasoline containers, garbage cans, agricultural storage vessels, septic tanks and sporting goods such as kayaks.
The process is undertaken by loading a charge of finely divided plastic copolymer into the mold "shell", then rotating the mold (usually, on two axes) while heating it to a temperature above the melting point of the plastic copolymer. The melted plastic flows through the mold cavity under the forces caused by the rotation of the apparatus. The rotation continues for sufficient time to allow the molten plastic to cover the surface of the mold. The mold is then cooled to permit the plastic to freeze into a solid.
The final stage of the molding cycle is the removal of the part from the rotomolding machine.
The time required to complete the molding cycle is a function of the bulk properties of the plastic which is being molded. For example, it is recognized by those skilled in the art that the plastic copolymer which is charged into the mold is preferably finely divided (i.e. ground into powder) and has a high bulk density and a narrow particle size distribution to facilitate the "free flow" of the copolymer.
It will also be appreciated that the physical properties of the rotomolded part are influenced by the use of a proper molding cycle time with "undercooked" parts having poor strength properties and "overcooked" parts suffering from poor appearance (a "burnt" color) and/or a deterioration of strength properties. It is desirable to have a short molding cycle (so as to improve the productivity of the expensive rotomolding machinery) and a broad "processing window" (i.e. the rotomolding composition ideally provides "properly cooked" parts in a short period of time but does not become "overcooked" for an extended period of time).
In addition, the properties of the rotomolded part are affected by the molecular structure of the polymer used to prepare the part. Physical properties of importance include stiffness (as indicated by the modulus of the part), environmental stress crack resistance (or "ESCR"), impact resistance and resistance to warpage.
Thermoplastic ethylene copolymer is a commonly used plastic copolymer for the manufacture of rotomolded parts. Conventional ethylene copolymer (which is generally prepared by the copolymerization of ethylene with a C4 to 10 alpha olefin in the presence of a chromium catalyst or a Ziegler Natta catalyst) is typically used. The alpha olefin \\chclients\IPGroup\Scott\SCSpec\2018023.docx comonomer produces "short chain branches" (SCB) in the copolymer. These SOB
reduce the crystallinity of the copolymer (in comparison to a linear ethylene homopolymer) and the copolymers typically have improved impact resistance in comparison to homopolymers. These conventional "polyethylenes" may be referred to as "heterogeneous" in the sense that the polyethylene is actually a mixture of different polyethylene chains having significantly different molecular weights and comonomer distributions. Most notably, a conventional heterogeneous ethylene copolymer generally contains three fractions:
i) a low molecular weight fraction having a high comonomer content (or high level of SOB) - this fraction is often referred to as "wax" or "extractables";
ii) a very high molecular weight fraction having essentially no comonomer -this fraction is often referred to as "homopolymer"; and iii) a fraction of intermediate molecular weight and SOB content.
These conventional polyethylenes are well suited for rotomolding. For example, whilst not wishing to be bound by theory, it has been postulated that the high molecular weight "homopolymer" fraction may enhance the stiffness or modulus of the rotomolded parts. However, as may be expected, the physical properties of a finished part (which has been molded with a proper cycle time) are largely "set" by the molecular structure of the polyethylene copolymer used to prepare the part. This, in turn, often results in finished parts with a suboptimal balance of properties.
More recently, homogeneous ethylene copolymers have become commercially available. These homogenous copolymers have a uniform (or narrow) molecular weight distribution and a uniform comonomer distribution. This, in turn, causes the homogeneous copolymers to have a well defined melting point (in comparison to the heterogeneous copolymers which have a melting point "range" or even multiple melting points).
The sharp melting point might have been expected to be advantageous for a rotomolding process. However, in practice, it has been found that parts prepared from a single homogeneous copolymer are prone to warpage and also generally have poor modulus or stiffness. Blends of homogeneous copolymers have been shown to mitigate this warpage problem, as disclosed in U.S. patent no. 7,201,864.
It is known to prepare storage containers for sulfuric acid by rotomolding polyethylene. These containers can become discolored after being exposed to sulfuric acid and the present invention mitigates this discoloration problem.
FIELD OF THE INVENTION
This invention provides a rotomolded polyethylene container that is resistant to discoloration when contacted with sulfuric acid.
BACKGROUND OF THE INVENTION
Rotational molding, also known as rotomolding, is a well known process which is widely used to produce hollow plastic parts such as gasoline containers, garbage cans, agricultural storage vessels, septic tanks and sporting goods such as kayaks.
The process is undertaken by loading a charge of finely divided plastic copolymer into the mold "shell", then rotating the mold (usually, on two axes) while heating it to a temperature above the melting point of the plastic copolymer. The melted plastic flows through the mold cavity under the forces caused by the rotation of the apparatus. The rotation continues for sufficient time to allow the molten plastic to cover the surface of the mold. The mold is then cooled to permit the plastic to freeze into a solid.
The final stage of the molding cycle is the removal of the part from the rotomolding machine.
The time required to complete the molding cycle is a function of the bulk properties of the plastic which is being molded. For example, it is recognized by those skilled in the art that the plastic copolymer which is charged into the mold is preferably finely divided (i.e. ground into powder) and has a high bulk density and a narrow particle size distribution to facilitate the "free flow" of the copolymer.
It will also be appreciated that the physical properties of the rotomolded part are influenced by the use of a proper molding cycle time with "undercooked" parts having poor strength properties and "overcooked" parts suffering from poor appearance (a "burnt" color) and/or a deterioration of strength properties. It is desirable to have a short molding cycle (so as to improve the productivity of the expensive rotomolding machinery) and a broad "processing window" (i.e. the rotomolding composition ideally provides "properly cooked" parts in a short period of time but does not become "overcooked" for an extended period of time).
In addition, the properties of the rotomolded part are affected by the molecular structure of the polymer used to prepare the part. Physical properties of importance include stiffness (as indicated by the modulus of the part), environmental stress crack resistance (or "ESCR"), impact resistance and resistance to warpage.
Thermoplastic ethylene copolymer is a commonly used plastic copolymer for the manufacture of rotomolded parts. Conventional ethylene copolymer (which is generally prepared by the copolymerization of ethylene with a C4 to 10 alpha olefin in the presence of a chromium catalyst or a Ziegler Natta catalyst) is typically used. The alpha olefin \\chclients\IPGroup\Scott\SCSpec\2018023.docx comonomer produces "short chain branches" (SCB) in the copolymer. These SOB
reduce the crystallinity of the copolymer (in comparison to a linear ethylene homopolymer) and the copolymers typically have improved impact resistance in comparison to homopolymers. These conventional "polyethylenes" may be referred to as "heterogeneous" in the sense that the polyethylene is actually a mixture of different polyethylene chains having significantly different molecular weights and comonomer distributions. Most notably, a conventional heterogeneous ethylene copolymer generally contains three fractions:
i) a low molecular weight fraction having a high comonomer content (or high level of SOB) - this fraction is often referred to as "wax" or "extractables";
ii) a very high molecular weight fraction having essentially no comonomer -this fraction is often referred to as "homopolymer"; and iii) a fraction of intermediate molecular weight and SOB content.
These conventional polyethylenes are well suited for rotomolding. For example, whilst not wishing to be bound by theory, it has been postulated that the high molecular weight "homopolymer" fraction may enhance the stiffness or modulus of the rotomolded parts. However, as may be expected, the physical properties of a finished part (which has been molded with a proper cycle time) are largely "set" by the molecular structure of the polyethylene copolymer used to prepare the part. This, in turn, often results in finished parts with a suboptimal balance of properties.
More recently, homogeneous ethylene copolymers have become commercially available. These homogenous copolymers have a uniform (or narrow) molecular weight distribution and a uniform comonomer distribution. This, in turn, causes the homogeneous copolymers to have a well defined melting point (in comparison to the heterogeneous copolymers which have a melting point "range" or even multiple melting points).
The sharp melting point might have been expected to be advantageous for a rotomolding process. However, in practice, it has been found that parts prepared from a single homogeneous copolymer are prone to warpage and also generally have poor modulus or stiffness. Blends of homogeneous copolymers have been shown to mitigate this warpage problem, as disclosed in U.S. patent no. 7,201,864.
It is known to prepare storage containers for sulfuric acid by rotomolding polyethylene. These containers can become discolored after being exposed to sulfuric acid and the present invention mitigates this discoloration problem.
2 \\chclients\IPGroup\Scott\SCSpec\2018023.docx SUMMARY OF THE INVENTION
One embodiment of this invention provides a method for improving the discoloration resistance of a rotational molded polyethylene container that is contacted with concentrated sulfuric acid, said method comprising the steps of 1) providing a stabilized ethylene copolymer composition, wherein said stabilized ethylene copolymer composition contains an additive package comprising A.1) a hindered phenolic primary antioxidant;
A.2) a hydroxylamine primary antioxidant;
B) a phosphite secondary antioxidant;
C) a hindered amine light stabilizer; and 2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container;
and
One embodiment of this invention provides a method for improving the discoloration resistance of a rotational molded polyethylene container that is contacted with concentrated sulfuric acid, said method comprising the steps of 1) providing a stabilized ethylene copolymer composition, wherein said stabilized ethylene copolymer composition contains an additive package comprising A.1) a hindered phenolic primary antioxidant;
A.2) a hydroxylamine primary antioxidant;
B) a phosphite secondary antioxidant;
C) a hindered amine light stabilizer; and 2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container;
and
3) contacting said rotational molded polyethylene container with concentrated sulfuric acid to produce an acid contacted container; wherein said acid contacted container has improved color in comparison to a control acid contacted container that is prepared using an additive package that does not contain any of said hydroxylamine primary antioxidant.
In another embodiment, there is provided a method for improving the discoloration resistance of a rotational molded polyethylene container that is contacted with concentrated sulfuric acid, said method comprising the steps of 1) providing a stabilized ethylene copolymer composition, wherein said stabilized ethylene copolymer composition contains an additive package consisting essentially of A.1) at least one hindered phenolic primary antioxidant (especially from 300 to 1500 ppm of at least one hindered phenolic primary antioxidant);
A.2) at least one hydroxylamine primary antioxidant (especially from 100 to 1000 ppm);
B) at least one phosphite secondary antioxidant (especially from 500 to 2000 ppm);
C) at least one hindered amine light stabilizer (especially from 500 to 5000 PPrn);
2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container;
and \\chclients\IPGroup\Scott\SCSpec\2018023.docx , 3) contacting said rotational molded polyethylene container with concentrated sulfuric acid to produce an acid contacted container; wherein said acid contacted container has improved color in comparison to a control acid contacted container that is prepared using an additive package that does not contain any of said hydroxylamine primary antioxidant.
The term "stabilized ethylene copolymer composition" simply refers to a composition that contains the ethylene copolymer composition plus the "additive package"
(that serves to stabilize the ethylene copolymer composition).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Rotational molding technology is well known and is described in the literature.
Reference may be made to United States Patent (USP) 5,530,055 (Needham), for further details concerning the operation of a rotomolding process. Two important process conditions to define a rotomolding process are the molding temperature and "cook" time (or heated molding time). A temperature of from 230 to 350 C and a heated molding time of from 10 to 60 minutes are suitable for this invention.
Ethylene copolymer compositions for use in this invention may be partially characterized by density and melt flow characteristics. In an embodiment, the density range is from 0.93 to 0.95 grams per cubic centimeter (especially 0.935 to 0.945) and the melt index ("12", as determined by ASTM D-1238, using a 2.16 kilogram load at a temperature of 190 C) is from 1 to 10 grams per 10 minutes (preferably 2 to 8). Melt index might be regarded as an indicator of molecular weight, though an inverse relationship between the two exists. That is, as the molecular weight of the polymer increases, the flow index (12) decreases.
In general, the term ethylene copolymer, as used herein, is meant to refer to a copolymer of ethylene with at least one alpha olefin monomer containing from 3 to 10 carbon atoms. Thus, ethylene homopolymers are excluded but terpolymers are included.
The physical properties of such ethylene copolymers are influenced by their molecular weight, molecular weight distribution, comonomer content and comonomer distribution. It is well known that the use of such comonomers produces copolymers that generally have decreased density and crystallinity as the amount of incorporated comonomer increases.
The ethylene copolymers used in this invention may be either heterogenous copolymers or homogeneous copolymers as explained below.
Heterogenous Ethylene Copolymers (or "Heterogeneous Copolymers") Conventional (heterogeneous) ethylene copolymers which are prepared with a conventional Ziegler-Natta (Z/N) catalyst generally have a comparatively broad molecular weight distribution (as defined by dividing weight average molecular weight, Mw, by
In another embodiment, there is provided a method for improving the discoloration resistance of a rotational molded polyethylene container that is contacted with concentrated sulfuric acid, said method comprising the steps of 1) providing a stabilized ethylene copolymer composition, wherein said stabilized ethylene copolymer composition contains an additive package consisting essentially of A.1) at least one hindered phenolic primary antioxidant (especially from 300 to 1500 ppm of at least one hindered phenolic primary antioxidant);
A.2) at least one hydroxylamine primary antioxidant (especially from 100 to 1000 ppm);
B) at least one phosphite secondary antioxidant (especially from 500 to 2000 ppm);
C) at least one hindered amine light stabilizer (especially from 500 to 5000 PPrn);
2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container;
and \\chclients\IPGroup\Scott\SCSpec\2018023.docx , 3) contacting said rotational molded polyethylene container with concentrated sulfuric acid to produce an acid contacted container; wherein said acid contacted container has improved color in comparison to a control acid contacted container that is prepared using an additive package that does not contain any of said hydroxylamine primary antioxidant.
The term "stabilized ethylene copolymer composition" simply refers to a composition that contains the ethylene copolymer composition plus the "additive package"
(that serves to stabilize the ethylene copolymer composition).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Rotational molding technology is well known and is described in the literature.
Reference may be made to United States Patent (USP) 5,530,055 (Needham), for further details concerning the operation of a rotomolding process. Two important process conditions to define a rotomolding process are the molding temperature and "cook" time (or heated molding time). A temperature of from 230 to 350 C and a heated molding time of from 10 to 60 minutes are suitable for this invention.
Ethylene copolymer compositions for use in this invention may be partially characterized by density and melt flow characteristics. In an embodiment, the density range is from 0.93 to 0.95 grams per cubic centimeter (especially 0.935 to 0.945) and the melt index ("12", as determined by ASTM D-1238, using a 2.16 kilogram load at a temperature of 190 C) is from 1 to 10 grams per 10 minutes (preferably 2 to 8). Melt index might be regarded as an indicator of molecular weight, though an inverse relationship between the two exists. That is, as the molecular weight of the polymer increases, the flow index (12) decreases.
In general, the term ethylene copolymer, as used herein, is meant to refer to a copolymer of ethylene with at least one alpha olefin monomer containing from 3 to 10 carbon atoms. Thus, ethylene homopolymers are excluded but terpolymers are included.
The physical properties of such ethylene copolymers are influenced by their molecular weight, molecular weight distribution, comonomer content and comonomer distribution. It is well known that the use of such comonomers produces copolymers that generally have decreased density and crystallinity as the amount of incorporated comonomer increases.
The ethylene copolymers used in this invention may be either heterogenous copolymers or homogeneous copolymers as explained below.
Heterogenous Ethylene Copolymers (or "Heterogeneous Copolymers") Conventional (heterogeneous) ethylene copolymers which are prepared with a conventional Ziegler-Natta (Z/N) catalyst generally have a comparatively broad molecular weight distribution (as defined by dividing weight average molecular weight, Mw, by
4 \\chclients\IPGroup\Scott\SCSpec\2018023.docx number average molecular weight, Mn - i.e. molecular weight distribution equals Mw/Mn) and a broad comonomer distribution. These copolymers typically contain at least three distinct polymer fractions, namely a small amount (generally less than 5 weight %) of a low molecular weight, high comonomer content material (also known as "wax"); a significant fraction (15 to 25 weight %) of material having a very high molecular weight and a low comonomer content (also known as "homopolymer"); with the remainder of the copolymer being of intermediate density and molecular weight.
This lack of uniformity with respect to molecular weight and comonomer distribution has several disadvantages for example, the "wax" fraction may limit the use of these interpolymers in applications which come into contact with food and the "homopolymer" fraction is often associated with the poor impact resistance of goods made with these interpolymers. In addition, these heterogeneous copolymers have a molecular weight distribution, Mw/Mn, of greater than 3Ø However, these copolymers can also have good Environmental Stress Crack Resistance (ESCR) and are suitable for use in this invention.
Homogenous Ethylene Copolymers (or "Homogeneous Copolymers") It is known to prepare rotomolded parts with a single "homogeneous" copolymer (i.e. a copolymer with a uniform comonomer distribution). Homogeneous copolymers do not contain the "high density" fraction which exists in conventional Ziegler Natta ("Z/N") copolymers and, thus, a homogeneous copolymer will have a lower (and sharper) melting point than a Z/N copolymer of similar molecular weight and density. This, in turn may allow cycle times to be reduced using a single homogeneous copolymer (in comparison to the cycle time required for similar Z/N copolymer). However, the resulting parts are prone to warpage. In addition, the rotomolded parts prepared from homogeneous copolymers have poor stiffness in comparison to parts prepared from Z/N copolymers. The well defined melting point of the homogeneous copolymers may also assist with the fabrication of custom parts (in which thin molds with irregular shapes must be filled within tight tolerances).
The warpage problem may be mitigated by using ethylene copolymer compositions that may contain at least two ethylene copolymer blend components. Each of these components may be prepared by the copolymerization of ethylene with a C4to20 alpha olefin in the presence of a catalyst system which produces homogenous copolymers (i.e.
as above, polymers with a narrow molecular weight distribution and narrow composition distribution). Exemplary catalyst systems include the vanadium catalyst system disclosed in USP 3,645,992 (Elston), "metallocene" catalysts (as disclosed, for example, in USP
This lack of uniformity with respect to molecular weight and comonomer distribution has several disadvantages for example, the "wax" fraction may limit the use of these interpolymers in applications which come into contact with food and the "homopolymer" fraction is often associated with the poor impact resistance of goods made with these interpolymers. In addition, these heterogeneous copolymers have a molecular weight distribution, Mw/Mn, of greater than 3Ø However, these copolymers can also have good Environmental Stress Crack Resistance (ESCR) and are suitable for use in this invention.
Homogenous Ethylene Copolymers (or "Homogeneous Copolymers") It is known to prepare rotomolded parts with a single "homogeneous" copolymer (i.e. a copolymer with a uniform comonomer distribution). Homogeneous copolymers do not contain the "high density" fraction which exists in conventional Ziegler Natta ("Z/N") copolymers and, thus, a homogeneous copolymer will have a lower (and sharper) melting point than a Z/N copolymer of similar molecular weight and density. This, in turn may allow cycle times to be reduced using a single homogeneous copolymer (in comparison to the cycle time required for similar Z/N copolymer). However, the resulting parts are prone to warpage. In addition, the rotomolded parts prepared from homogeneous copolymers have poor stiffness in comparison to parts prepared from Z/N copolymers. The well defined melting point of the homogeneous copolymers may also assist with the fabrication of custom parts (in which thin molds with irregular shapes must be filled within tight tolerances).
The warpage problem may be mitigated by using ethylene copolymer compositions that may contain at least two ethylene copolymer blend components. Each of these components may be prepared by the copolymerization of ethylene with a C4to20 alpha olefin in the presence of a catalyst system which produces homogenous copolymers (i.e.
as above, polymers with a narrow molecular weight distribution and narrow composition distribution). Exemplary catalyst systems include the vanadium catalyst system disclosed in USP 3,645,992 (Elston), "metallocene" catalysts (as disclosed, for example, in USP
5,324,800), "constrained geometry" catalysts (as disclosed, for example, in USP
\\chclients\IPGroun\Scott\SCSnec\2018023.docx 5,064,802 Stevens et al.) and the phosphinimine catalyst systems described in the USP
\\chclients\IPGroun\Scott\SCSnec\2018023.docx 5,064,802 Stevens et al.) and the phosphinimine catalyst systems described in the USP
6,372,864 (Brown et al.).
The blend components may be prepared as distinct polymers in separate polymerization reactions and then blended together to provide the present compositions.
The blend components may be blended using conventional mixing/blending equipment such as a single or twin sinew extruder; and internal batch mixer such as a Banbury TM
mixer; or a continuous mixer such as a FarrelTM mixer. The mixing time and temperatures may be readily optimized by those skilled in the art without undue experimentation. As a guideline, mixing temperatures of from 150 to 250 C are suitable and mixing times of 1-10 minutes may provide satisfactory results. Alternatively (and preferably), the blend components may be prepared in a multiple reactor polymerization system.
Homogenous copolymers as described above are suitable for use in the present invention.
Typically, each blend component is a copolymer of ethylene with C4to8 alpha olefin such as butene-1, pentene-1, 4-methyl-1-pentene, hexene-1 or octene-1; with hexene-1 and octene-1 being most preferred.
Additives Rotomolding compositions conventionally contain an additive package to protect the polymer from decomposing during the processing and/or exposure to the elements and to improve processing cycle times and windows. Reference is made to "Influence of Stabilizers in Rotational Molding" (Gupta and Stadler; paper presented at 22nd Annual Fall Meeting of the Association of Rotational Molders; 5-8 October 1997) for details.
The additives may be incorporated into the compositions using mixing equipment such as an extruder, or internal batch mixer (also known as a Banbury TM
mixer). The additive may be added "neat" (i.e. directly to the copolymer); as a "masterbatch" (i.e. by premixing the additives with a small amount of polyethylene which is subsequently mixed with the bulk of the composition); or as "preblends" (i.e. mixtures of the additives).
The additive system of this invention includes at least one Hindered Amine Light Stabilizers (or "HALS"); at least one secondary antioxidant that is preferably a phosphite or phosphonite (especially a diphosphite as illustrated in the examples); and at least two "primary" antioxidants, namely a hindered phenol and a hydroxyl amine.
In summary, the additive package used in the present invention must contain at least four components, namely 1) a first primary antioxidant (Part 1, below);
2) a second primary antioxidant (Part 1); 3) a secondary antioxidant (Part 2); and 4) a hindered amine light stabilizer (Part 3).
Part 1. Primary Antioxidants \\chclients\IPGrouo\Scott\SCSoec\2018023.docx As used herein, the term primary antioxidant refers to a molecule which is capable of quenching free radicals in a polyethylene matrix. Examples of primary antioxidants include hindered phenols, hydroxylamines, amine oxides and lactones. The present invention must use both a hindered phenol (See 1.1 and 1.4, below) and a hydroxylamine (1.5 below) ¨ i.e. two primary antioxidants are required. Other primary antioxidants may optionally be included. Exemplary primary antioxidants are described in more detail in section 1 below.
1.1 Alkylated Mono-Phenols (also referred to as "hindered phenols") For example, 2,6-di-tert-butyl-4-methylphenol; 2-tert-butyl-4,6-dimethylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,6-di-tert-butyl-4-n-butylphenol; 2,6-di-tert-buty1-4isobutylphenol; 2,6-dicyclopenty1-4-methylphenol; 2-(.alpha.-methylcyclohexyl)-4,6 dimethylphenol; 2,6-di-octadecy1-4-methylphenol; 2,4,6,-tricyclohexyphenol;
2,6-di-tert-buty1-4-methoxymethylphenol, Octadecy1-3-(3,5-di-tert-butyl-4-hydroxyphenyI)-propionate (e.g. 1RGANOXTm1076, from BASF); pentaerythritol tetrakis(3-(5-di-tert-buty1-4-hydroxyphenol)propionate) (e.g. 1RGANOXTm1010, from BASF); and 1,3,5-tris(3,5-di-tert-buty1-4-hydroxybenzy1)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (e.g. IRGANOXTM
3114, from BASF).
1.2 Alkylated Hydrocwinones For example, 2,6di-tert-butyl-4-methoxyphenol; 2,5-di-tert-butylhydroquinone;
2,5-di-tert-amyl-hydroquinone; and 2,6dipheny1-4-octadecyloxyphenol.
1.3 Hydroxylated Thiodiphenyl Ethers For example, 2,2'-thio-bis-(6-tert-buty1-4-methylphenol); 2,2'-thio-bis-(4-octylphenol); 4,4'thio-bis-(6-tertbuty1-3-methylphenol); and 4,4'-thio-bis-(6-tert-buty1-2-methylphenol).
1.4 Alkylidene-Bisphenols (also referred to as "hindered phenols") For example, 2,2'-methylene-bis-(6-tert-buty1-4-methylphenol); 2,2'-methylene-bis-(6-tert-buty1-4-ethylphenol); 2,2'-methylene-bis-(4-methy1-6-(alpha-methylcyclohexyl)phenol); 2,2'-methylene-bis-(4-methy1-6-cyclohexyiphenol);
2,2'-methylene-bis-(6-nony1-4-methylphenol); 2,2'-methylene-bis-(6-nony1-4methylphenol);
2,2'-methylene-bis-(6-(alpha-methylbenzy1)-4-nonylphenol); 2,2'-methylene-bis-(6-(alpha, alpha-dimethylbenzyI)-4-nonyl-phenol); 2,2'-methylene-bis-(4,6-di-tert-butylphenol); 2,2'-ethylidene-bis-(6-tert-buty1-4-isobutylphenol); 4,41methylene-bis-(2,6-di-tert-butylphenol);
4,4'-methylene-bis-(6-tert-butyl-2-methylphenol); 1,1-bis-(5-tert-buty1-4-hydroxy-2-methylphenol)butane 2,6-di-(3-tert-butyl-5-methyl-2-hydroxybenzyI)-4-methylphenol;
1,1,3-tris-(5-tert-buty1-4-hydroxy-2-methylphenyl)butane; 1,1-bis-(5-tert-buty1-4-hydroxy2-methylpheny1)-3-dodecyl-mercaptobutane; ethyleneglycol-bis-(3,3,-bis-(3'-tert-buty1-4'-
The blend components may be prepared as distinct polymers in separate polymerization reactions and then blended together to provide the present compositions.
The blend components may be blended using conventional mixing/blending equipment such as a single or twin sinew extruder; and internal batch mixer such as a Banbury TM
mixer; or a continuous mixer such as a FarrelTM mixer. The mixing time and temperatures may be readily optimized by those skilled in the art without undue experimentation. As a guideline, mixing temperatures of from 150 to 250 C are suitable and mixing times of 1-10 minutes may provide satisfactory results. Alternatively (and preferably), the blend components may be prepared in a multiple reactor polymerization system.
Homogenous copolymers as described above are suitable for use in the present invention.
Typically, each blend component is a copolymer of ethylene with C4to8 alpha olefin such as butene-1, pentene-1, 4-methyl-1-pentene, hexene-1 or octene-1; with hexene-1 and octene-1 being most preferred.
Additives Rotomolding compositions conventionally contain an additive package to protect the polymer from decomposing during the processing and/or exposure to the elements and to improve processing cycle times and windows. Reference is made to "Influence of Stabilizers in Rotational Molding" (Gupta and Stadler; paper presented at 22nd Annual Fall Meeting of the Association of Rotational Molders; 5-8 October 1997) for details.
The additives may be incorporated into the compositions using mixing equipment such as an extruder, or internal batch mixer (also known as a Banbury TM
mixer). The additive may be added "neat" (i.e. directly to the copolymer); as a "masterbatch" (i.e. by premixing the additives with a small amount of polyethylene which is subsequently mixed with the bulk of the composition); or as "preblends" (i.e. mixtures of the additives).
The additive system of this invention includes at least one Hindered Amine Light Stabilizers (or "HALS"); at least one secondary antioxidant that is preferably a phosphite or phosphonite (especially a diphosphite as illustrated in the examples); and at least two "primary" antioxidants, namely a hindered phenol and a hydroxyl amine.
In summary, the additive package used in the present invention must contain at least four components, namely 1) a first primary antioxidant (Part 1, below);
2) a second primary antioxidant (Part 1); 3) a secondary antioxidant (Part 2); and 4) a hindered amine light stabilizer (Part 3).
Part 1. Primary Antioxidants \\chclients\IPGrouo\Scott\SCSoec\2018023.docx As used herein, the term primary antioxidant refers to a molecule which is capable of quenching free radicals in a polyethylene matrix. Examples of primary antioxidants include hindered phenols, hydroxylamines, amine oxides and lactones. The present invention must use both a hindered phenol (See 1.1 and 1.4, below) and a hydroxylamine (1.5 below) ¨ i.e. two primary antioxidants are required. Other primary antioxidants may optionally be included. Exemplary primary antioxidants are described in more detail in section 1 below.
1.1 Alkylated Mono-Phenols (also referred to as "hindered phenols") For example, 2,6-di-tert-butyl-4-methylphenol; 2-tert-butyl-4,6-dimethylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,6-di-tert-butyl-4-n-butylphenol; 2,6-di-tert-buty1-4isobutylphenol; 2,6-dicyclopenty1-4-methylphenol; 2-(.alpha.-methylcyclohexyl)-4,6 dimethylphenol; 2,6-di-octadecy1-4-methylphenol; 2,4,6,-tricyclohexyphenol;
2,6-di-tert-buty1-4-methoxymethylphenol, Octadecy1-3-(3,5-di-tert-butyl-4-hydroxyphenyI)-propionate (e.g. 1RGANOXTm1076, from BASF); pentaerythritol tetrakis(3-(5-di-tert-buty1-4-hydroxyphenol)propionate) (e.g. 1RGANOXTm1010, from BASF); and 1,3,5-tris(3,5-di-tert-buty1-4-hydroxybenzy1)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (e.g. IRGANOXTM
3114, from BASF).
1.2 Alkylated Hydrocwinones For example, 2,6di-tert-butyl-4-methoxyphenol; 2,5-di-tert-butylhydroquinone;
2,5-di-tert-amyl-hydroquinone; and 2,6dipheny1-4-octadecyloxyphenol.
1.3 Hydroxylated Thiodiphenyl Ethers For example, 2,2'-thio-bis-(6-tert-buty1-4-methylphenol); 2,2'-thio-bis-(4-octylphenol); 4,4'thio-bis-(6-tertbuty1-3-methylphenol); and 4,4'-thio-bis-(6-tert-buty1-2-methylphenol).
1.4 Alkylidene-Bisphenols (also referred to as "hindered phenols") For example, 2,2'-methylene-bis-(6-tert-buty1-4-methylphenol); 2,2'-methylene-bis-(6-tert-buty1-4-ethylphenol); 2,2'-methylene-bis-(4-methy1-6-(alpha-methylcyclohexyl)phenol); 2,2'-methylene-bis-(4-methy1-6-cyclohexyiphenol);
2,2'-methylene-bis-(6-nony1-4-methylphenol); 2,2'-methylene-bis-(6-nony1-4methylphenol);
2,2'-methylene-bis-(6-(alpha-methylbenzy1)-4-nonylphenol); 2,2'-methylene-bis-(6-(alpha, alpha-dimethylbenzyI)-4-nonyl-phenol); 2,2'-methylene-bis-(4,6-di-tert-butylphenol); 2,2'-ethylidene-bis-(6-tert-buty1-4-isobutylphenol); 4,41methylene-bis-(2,6-di-tert-butylphenol);
4,4'-methylene-bis-(6-tert-butyl-2-methylphenol); 1,1-bis-(5-tert-buty1-4-hydroxy-2-methylphenol)butane 2,6-di-(3-tert-butyl-5-methyl-2-hydroxybenzyI)-4-methylphenol;
1,1,3-tris-(5-tert-buty1-4-hydroxy-2-methylphenyl)butane; 1,1-bis-(5-tert-buty1-4-hydroxy2-methylpheny1)-3-dodecyl-mercaptobutane; ethyleneglycol-bis-(3,3,-bis-(3'-tert-buty1-4'-
7 wendientsvP(Imun\Smff\SCSnec\2018023.docx hydroxypheny1)-butyrate)-di-(3-tert-buty1-4-hydroxy-5-methylpeny1)-dicyclopentadiene; di-(2-(3'-tert-buty1-2'hydroxy-5Thethylbenzy1)-6-tert-butyl-4-methylphenyl)terephthalate; and other phenolics such as monoacrylate esters of bisphenols such as ethylidiene bis-2,4-di-t-butylphenol monoacrylate ester.
1.5 Hydroxvlamines For example, N,N-dibenzylhydroxylamine; N,N-diethylhydroxylamine; N,N-dioctylhydroxylamine; N,N-dilaurylhydroxylamine; N,N-ditetradecylhydroxylamine; N,N-dihexadecylhydroxylamine; N,N-dioctadecylhydroxylamine; N-hexadecyl-N-octadecylhydroxylamnine; N-heptadecyl-N-octadecylhydroxylamine; and N,N-dialkylhydroxylamine derived from hydrogenated tallow amine (e.g. IRGASTABTm FS 042, from BASF). The analogous amine oxides (as disclosed in USP 5,844,029, Prabhu et al.) are also suitable.
Part 2. Secondary Antioxidants The term secondary antioxidant refers to an additive that is used to scavenge peroxides. Examples include triphenyl phosphite; diphenylalkyl phosphates;
phenyldialkyl phosphates; tris(nonyl-phenyl)phosphite; trilauryl phosphite; trioctadecyl phosphite;
distearyl pentaerythritol diphosphite; tris(2,4-di-tert-butylphenyl)phosphite (e.g.
IRGASTABTm 168, from BASF); diisodecyl pentaerythritol diphosphite; 2,4,6-tri-tert-butylpheny1-2-buty1-2-ethyl-1,3-propanediol phosphite; bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite tristearyl sorbitol triphosphite;
tetrakis(2,4-di-tert-butylpheny1)4,41-biphenylene and bis (2,4-dicumylphenyl) pentaerythritol diphosphite (e.g.
DOVERPHOSTM S-9228, from Dover Chemicals) and sulfur compounds (especially esters of betatriodipropionic acid) and dialkylsulfides. Phosphorus compounds are preferred, especially the phosphites and phosphonites. A combination of more than one secondary antioxidant may be used.
It is preferred to include a diphosphite (especially DOVERPHOSTM S-9228) and a monophosphite (especially IRGAFOSTM 168) as these additives may extend the "processing window" (i.e. allowing the part to remain in the mold for an extended period of time without becoming "overcooked" to the point of discoloration and/or the loss of physical properties). The preferred amount of secondary antioxidant is from 100 to 3000 ppm.
Part 3. Hindered Amine Light Stabilizers In general, a hindered amine light stabilizer (HALS) has a hindered amine functional group (which is preferably a tetramethyl piperidine group) together with an organic "structure" or "backbone" that is used to deliver the functional group to the polymer that is being stabilized. The number average molecular weight (Mn) of these
1.5 Hydroxvlamines For example, N,N-dibenzylhydroxylamine; N,N-diethylhydroxylamine; N,N-dioctylhydroxylamine; N,N-dilaurylhydroxylamine; N,N-ditetradecylhydroxylamine; N,N-dihexadecylhydroxylamine; N,N-dioctadecylhydroxylamine; N-hexadecyl-N-octadecylhydroxylamnine; N-heptadecyl-N-octadecylhydroxylamine; and N,N-dialkylhydroxylamine derived from hydrogenated tallow amine (e.g. IRGASTABTm FS 042, from BASF). The analogous amine oxides (as disclosed in USP 5,844,029, Prabhu et al.) are also suitable.
Part 2. Secondary Antioxidants The term secondary antioxidant refers to an additive that is used to scavenge peroxides. Examples include triphenyl phosphite; diphenylalkyl phosphates;
phenyldialkyl phosphates; tris(nonyl-phenyl)phosphite; trilauryl phosphite; trioctadecyl phosphite;
distearyl pentaerythritol diphosphite; tris(2,4-di-tert-butylphenyl)phosphite (e.g.
IRGASTABTm 168, from BASF); diisodecyl pentaerythritol diphosphite; 2,4,6-tri-tert-butylpheny1-2-buty1-2-ethyl-1,3-propanediol phosphite; bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite tristearyl sorbitol triphosphite;
tetrakis(2,4-di-tert-butylpheny1)4,41-biphenylene and bis (2,4-dicumylphenyl) pentaerythritol diphosphite (e.g.
DOVERPHOSTM S-9228, from Dover Chemicals) and sulfur compounds (especially esters of betatriodipropionic acid) and dialkylsulfides. Phosphorus compounds are preferred, especially the phosphites and phosphonites. A combination of more than one secondary antioxidant may be used.
It is preferred to include a diphosphite (especially DOVERPHOSTM S-9228) and a monophosphite (especially IRGAFOSTM 168) as these additives may extend the "processing window" (i.e. allowing the part to remain in the mold for an extended period of time without becoming "overcooked" to the point of discoloration and/or the loss of physical properties). The preferred amount of secondary antioxidant is from 100 to 3000 ppm.
Part 3. Hindered Amine Light Stabilizers In general, a hindered amine light stabilizer (HALS) has a hindered amine functional group (which is preferably a tetramethyl piperidine group) together with an organic "structure" or "backbone" that is used to deliver the functional group to the polymer that is being stabilized. The number average molecular weight (Mn) of these
8 \\chclients\IPGroun\Scott\SCSnec\2018023.docx HALS structures typically range from about 600 to about 15,000. HALS are well known items of commerce and are readily available from such suppliers as Ciba Specialty Chemicals and Cytec Incorporated.
Examples of HALS include bis (2,2,6,6-tetramethylpiperidyI)-sebacate; bis-5 (1,2,2,6,6-pentamethylpiperidy1)-sebacate; n-butyl-3,5-di-tert-buty1-4-hydroxybenzyl malonic acid bis(1,2,2,6,6,-pentamethylpiperidyl)ester; condensation product of 1-hydroxyethy1-2,2,6,6-tetramethy1-4-hydroxy-piperidine and succinic acid;
condensation product of N,N'-(2,2,6,6-tetramethylpiperidyI)-hexamethylendiamine and 4-tert-octylamino-2,6-dichloro-1,3,5-s-triazine; tris-(2,2,6,6-tetramethylpiperidyI)-nitrilotriacetate, tetrakis-(2,2,6,6-tetramethy1-4-piperidy1)-1,2,3,4butane-tetra-arbonic acid; and 1,1'(1,2-ethanediyI)-bis-(3,3,5,5-tetramethylpiperazinone). Some HALS (Hindered Amines Light Stabilizers) may be described as carboxylic acid 2,2,6,6-tetramethyl piperidinol esters (e.g.
T1NUUINTm 622, form BASF and CYASORBTM UV-3346 from Cytec). Such amines include hydroxylamines derived from hindered amines, such as di(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-y1) sebacate; 1-hydroxy 2,2,6,6-tetramethy1-4-benzoxypiperidine; 1-hydroxy-2,2,6,6-tetramethy1-4-(3,5-di-tert-buty1-4-hydroxy hydrocinnamoyloxy)-piperdine;
and N-(1-hydroxy-2,2,6,6-tetramethyl-piperidin-4-yI)-epsiloncaprolactam.
Additional details concerning suitable HALS for use in the present invention are disclosed in U.S.P. 5,037,870 and 5,134,181, the disclosures of which are incorporated herein by reference. The preferred amount of HALS is from 300 to 3000 ppm.
Other Additives Zinc Oxide ZnO is widely used as a polyolefin additive. Any of the commercially available ZnO
products which are presently used in polyolefins are potentially suitable for use in the present invention. Preferred zinc oxide is prepared by the so called "French Process" and has a mean particle size of less than 1 micron. ZnO sold under the trademark "KADOX
911" is suitable. Representative physical properties of KADOX 911 ZnO are reported by the manufacturer as: a) mean particle size: 0.12 microns and b) surface area:
Examples of HALS include bis (2,2,6,6-tetramethylpiperidyI)-sebacate; bis-5 (1,2,2,6,6-pentamethylpiperidy1)-sebacate; n-butyl-3,5-di-tert-buty1-4-hydroxybenzyl malonic acid bis(1,2,2,6,6,-pentamethylpiperidyl)ester; condensation product of 1-hydroxyethy1-2,2,6,6-tetramethy1-4-hydroxy-piperidine and succinic acid;
condensation product of N,N'-(2,2,6,6-tetramethylpiperidyI)-hexamethylendiamine and 4-tert-octylamino-2,6-dichloro-1,3,5-s-triazine; tris-(2,2,6,6-tetramethylpiperidyI)-nitrilotriacetate, tetrakis-(2,2,6,6-tetramethy1-4-piperidy1)-1,2,3,4butane-tetra-arbonic acid; and 1,1'(1,2-ethanediyI)-bis-(3,3,5,5-tetramethylpiperazinone). Some HALS (Hindered Amines Light Stabilizers) may be described as carboxylic acid 2,2,6,6-tetramethyl piperidinol esters (e.g.
T1NUUINTm 622, form BASF and CYASORBTM UV-3346 from Cytec). Such amines include hydroxylamines derived from hindered amines, such as di(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-y1) sebacate; 1-hydroxy 2,2,6,6-tetramethy1-4-benzoxypiperidine; 1-hydroxy-2,2,6,6-tetramethy1-4-(3,5-di-tert-buty1-4-hydroxy hydrocinnamoyloxy)-piperdine;
and N-(1-hydroxy-2,2,6,6-tetramethyl-piperidin-4-yI)-epsiloncaprolactam.
Additional details concerning suitable HALS for use in the present invention are disclosed in U.S.P. 5,037,870 and 5,134,181, the disclosures of which are incorporated herein by reference. The preferred amount of HALS is from 300 to 3000 ppm.
Other Additives Zinc Oxide ZnO is widely used as a polyolefin additive. Any of the commercially available ZnO
products which are presently used in polyolefins are potentially suitable for use in the present invention. Preferred zinc oxide is prepared by the so called "French Process" and has a mean particle size of less than 1 micron. ZnO sold under the trademark "KADOX
911" is suitable. Representative physical properties of KADOX 911 ZnO are reported by the manufacturer as: a) mean particle size: 0.12 microns and b) surface area:
9.0 m2/g.
Polyamide Stabilizers For example, copper salts in combination with iodides and/or phosphorus compounds and salts of divalent manganese.
Basic Co-stabilizers For example, melamine; polyvinylpyrrolidone; dicyandiamide; triallyl cyanurate;
urea derivatives; hydrazine derivatives; amines; polyamides; polyurethanes;
alkali metal salts and alkaline earth metal salts of higher fatty acids, for example, Ca stearate, calcium stearoyl lactate, calcium lactate, Zn stearate, Mg stearate, Na ricinoleate and K palmitate;
\\chclients\IPGroup\Scott\SCSDe62018023.docx _ antimony pyrocatecholate or zinc pyrocatecholate, including neutralizers such as hydrotalcites and synthetic hydrotalcites; and Li, Na, Mg, Ca, Al hydroxy carbonates.
Nucleating Agents For example, 4-tert-butylbenzoic acid; adipic acid; diphenylacetic acid;
sodium salt of methylene bis-2,4-dibutylphenyl; cyclic phosphate esters; sorbitol tris-benzaldehyde acetal; and sodium salt of bis(2,4-di-t-butylphenyl) phosphate or Na salt of ethylidene bis(2,4-di-t-butyl phenyl)phosphate. Nucleating agents may improve stiffness of the rotomolded part.
Fillers and Reinforcing Agents For example, calcium carbonate; silicates; glass fibers; asbestos; talc;
kaolin; mica;
barium sulfate; metal oxides and hydroxides; carbon black and graphite.
Miscellaneous For example, plasticizers; UV absorbers; epoxidized vegetable oils, such as epoxidized soybean oils; lubricants; emulsifiers; pigments; optical brighteners; flame proofing agents; anti-static agents; blowing agents and thiosynergists, such as dilaurythiodipropionate or distearylthiodipropionate.
Crosslinkable rotomolded parts are contemplated. As disclosed in USP 5,367,025 (Needham) crosslinking agents may include a combination of organic peroxide initiator and a crosslinking co-agent. For rotomolding, dialkyl peroxides used include 2,5-dimethy1-2,5-di(t-butylperoxy)hexane or alpha,alpha'-bis(t-butylperoxy)diisopropylbenzene or those disclosed in USP 3,214,422. Co-agents used by those experienced in the art of crosslinking polyethylene, include triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, trimethololpropane trimethacrylate and related monomers.
EXAMPLES
(Comparative) Example 1 Experimental procedures are described below:
Two different types of ethylene copolymer were used. One was prepared with a conventional Ziegler Natta (Z(N) catalyst and had a molecular weight distribution, Mw/Mn, of between 3.2 and 3.5. This is referred to in Table 1 as "ZN1" and it had a melt index, 12, of 2 g/10 minutes and a density of 0.941g/cc.
A "single site catalyst" (SSC) copolymer was also used and is identified as SSC1 in Table 1. SSC1 had a melt index, 12, of 1.7 g/10 minutes and a density of 0.945 g/cc. In addition, SSC1 is further characterized by being a blend of two ethylene-octene blend components and was prepared in accordance with the teachings of U.S. Patent 7,201,864 (Weber et al.).
\\chclients\IPGrourAScott\SCSDec\2018023.docx These ethylene copolymers were blended with the additive packages described in Table 1 and ground into fine powder for the preparation of rotomolded parts.
For clarification: the compounded copolymer used in experiment 2 was conventional polyethylene ZN1 and contained 300 ppm of primary antioxidant; 1200 ppm of secondary antioxidant (Irgafos 168) and 200 ppm of HALS. This composition is comparative because it does not contain hydroxylamine.
Rotomolded parts were then prepared in a rotational molding machine sold under the tradename Rotospeed RS3-160 by Ferry Industries Inc. The machine has two arms which rotate about a central axis. Each arm is fitted with a plate which rotates on an axis that is roughly perpendicular to the axis of rotation of the arm. Each plate is fitted with three cast aluminum molds that produce plastic cubes having dimensions of 12.5 inches (31.8 cm) x 12.5 inches x 12.5 inches. These molds produce parts having a nominal thickness of about 0.25 inches (0.64 cm) when initially filled with a standard charge of about 3.7 kg of ethylene copolymer.
A gas fired furnace which is capable of providing 2 million British thermal units (Btu) per hour is used to provide hot air that is circulated about the molds by a fan. The temperature within the enclosed oven is typically maintained at a temperature of between 230 C (446 F) and 350 C (662 F) for specified periods of time while the machine rotates the arms (typically, at about 8 revolutions per minute (rpm) and the plate (typically, at about 2 rpm). The compositions shown in Table 1 were "cooked" for a molding cycle of 40 minutes with an oven temperature of 440 F.
The "cooked parts" are then cooled by opening the oven. Water spray may also be used to facilitate cooling. "Cook times", rotation speed, temperatures and cooling cycles are computer controlled with appropriate software which also includes a data acquisition system.
Test plaques were cut from the molded cubes. The plaques were exposed to concentrated sulfuric acid (98% H2SO4) at 70 C (As used herein, the term concentrated sulfuric acid refers to a liquid that contains from about 95 to 99% sulfuric acid by weight.
In general, "concentrated sulfuric acid" in commercial use contains about 98%
sulfuric acid).
The comparative compositions discolored after contact with the concentrated sulfuric acid. The following color scale is used to describe increasing levels of discoloration.
0 ¨ White 1 ¨ Tan 2 ¨ Light brown \\chclients\IPGrouo\Scott\SCSoec\2018023.docx 3 ¨ Dark brown/grey 4 - Black Both of the compositions of this example were severely discolored (to black, number 4 on the above scale) after contact with concentrated sulfuric acid at 70 C for 8 days.
\\chclients\IPGroup\ScottISCSnec\2018023.docx Experiment Copolymer MI2 Density HALS
First Secondary Second (g/10 min) (g/cm3) (ppm) Primary AO Primary AO
AO (ppm) (ppm) (ppm) 0 1 SSC1 1.70 0.945 C-944: 750 0 1-168: 550 FS 042: 250 T-622: 750 S-9228: 450 2 ZN1 2.0 0.941 C-3346:2000 1-3114:300 1-168:1200 0 C-944 = Chimassorb 944; T-622 = Tinuvin 622; C-3346 = Cyasorb UV-3346.
1-3114 = Irganox 3114. 1-168 = lrgafos 168; S-9228 = Doverphos S-9228. 5 FS
042 = Irgastabe FS 042;
Both experiments 1 and 2 are comparative because each of the compositions only contained a single primary antioxidant ¨ SSC1 contained only the hydroxylamine (sold under the trademark Irgastab FS042) and ZN1 contained only a phenolic (sold under the tradename Irganox 3114).
\\chclients\IPGroup\Scott\SCSpec\2018023.docx ¨ -Example 2 The formulations shown in Table 2 were used in this example. The rotational molding procedures were similar to those described above except that the molding time was reduced to 34 minutes and the temperature was increased to 480 F. Test plaques were cut from the molded cubes and exposed to concentrated sulfuric acid (98 weight%
H2SO4) at 70 C for the times shown in Table 3. Color values are also presented in Table 3.
The data in Table 3 illustrate that the composition that was prepared with the two different primary antioxidants (namely a phenolic and a hydroxylamine) has improved resistance to discoloration.
\\chclients\IPGrourAScott\SCSDec\2018023.docx 0 Example 2 Formulations 0 Experiment Copolymer MI2 Density HALS
First Secondary Second (g/10 min) (g/cm3) (ppm) Primary AO AO Primary AO
co (ppm) (ppm) (PPrn)
Polyamide Stabilizers For example, copper salts in combination with iodides and/or phosphorus compounds and salts of divalent manganese.
Basic Co-stabilizers For example, melamine; polyvinylpyrrolidone; dicyandiamide; triallyl cyanurate;
urea derivatives; hydrazine derivatives; amines; polyamides; polyurethanes;
alkali metal salts and alkaline earth metal salts of higher fatty acids, for example, Ca stearate, calcium stearoyl lactate, calcium lactate, Zn stearate, Mg stearate, Na ricinoleate and K palmitate;
\\chclients\IPGroup\Scott\SCSDe62018023.docx _ antimony pyrocatecholate or zinc pyrocatecholate, including neutralizers such as hydrotalcites and synthetic hydrotalcites; and Li, Na, Mg, Ca, Al hydroxy carbonates.
Nucleating Agents For example, 4-tert-butylbenzoic acid; adipic acid; diphenylacetic acid;
sodium salt of methylene bis-2,4-dibutylphenyl; cyclic phosphate esters; sorbitol tris-benzaldehyde acetal; and sodium salt of bis(2,4-di-t-butylphenyl) phosphate or Na salt of ethylidene bis(2,4-di-t-butyl phenyl)phosphate. Nucleating agents may improve stiffness of the rotomolded part.
Fillers and Reinforcing Agents For example, calcium carbonate; silicates; glass fibers; asbestos; talc;
kaolin; mica;
barium sulfate; metal oxides and hydroxides; carbon black and graphite.
Miscellaneous For example, plasticizers; UV absorbers; epoxidized vegetable oils, such as epoxidized soybean oils; lubricants; emulsifiers; pigments; optical brighteners; flame proofing agents; anti-static agents; blowing agents and thiosynergists, such as dilaurythiodipropionate or distearylthiodipropionate.
Crosslinkable rotomolded parts are contemplated. As disclosed in USP 5,367,025 (Needham) crosslinking agents may include a combination of organic peroxide initiator and a crosslinking co-agent. For rotomolding, dialkyl peroxides used include 2,5-dimethy1-2,5-di(t-butylperoxy)hexane or alpha,alpha'-bis(t-butylperoxy)diisopropylbenzene or those disclosed in USP 3,214,422. Co-agents used by those experienced in the art of crosslinking polyethylene, include triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, trimethololpropane trimethacrylate and related monomers.
EXAMPLES
(Comparative) Example 1 Experimental procedures are described below:
Two different types of ethylene copolymer were used. One was prepared with a conventional Ziegler Natta (Z(N) catalyst and had a molecular weight distribution, Mw/Mn, of between 3.2 and 3.5. This is referred to in Table 1 as "ZN1" and it had a melt index, 12, of 2 g/10 minutes and a density of 0.941g/cc.
A "single site catalyst" (SSC) copolymer was also used and is identified as SSC1 in Table 1. SSC1 had a melt index, 12, of 1.7 g/10 minutes and a density of 0.945 g/cc. In addition, SSC1 is further characterized by being a blend of two ethylene-octene blend components and was prepared in accordance with the teachings of U.S. Patent 7,201,864 (Weber et al.).
\\chclients\IPGrourAScott\SCSDec\2018023.docx These ethylene copolymers were blended with the additive packages described in Table 1 and ground into fine powder for the preparation of rotomolded parts.
For clarification: the compounded copolymer used in experiment 2 was conventional polyethylene ZN1 and contained 300 ppm of primary antioxidant; 1200 ppm of secondary antioxidant (Irgafos 168) and 200 ppm of HALS. This composition is comparative because it does not contain hydroxylamine.
Rotomolded parts were then prepared in a rotational molding machine sold under the tradename Rotospeed RS3-160 by Ferry Industries Inc. The machine has two arms which rotate about a central axis. Each arm is fitted with a plate which rotates on an axis that is roughly perpendicular to the axis of rotation of the arm. Each plate is fitted with three cast aluminum molds that produce plastic cubes having dimensions of 12.5 inches (31.8 cm) x 12.5 inches x 12.5 inches. These molds produce parts having a nominal thickness of about 0.25 inches (0.64 cm) when initially filled with a standard charge of about 3.7 kg of ethylene copolymer.
A gas fired furnace which is capable of providing 2 million British thermal units (Btu) per hour is used to provide hot air that is circulated about the molds by a fan. The temperature within the enclosed oven is typically maintained at a temperature of between 230 C (446 F) and 350 C (662 F) for specified periods of time while the machine rotates the arms (typically, at about 8 revolutions per minute (rpm) and the plate (typically, at about 2 rpm). The compositions shown in Table 1 were "cooked" for a molding cycle of 40 minutes with an oven temperature of 440 F.
The "cooked parts" are then cooled by opening the oven. Water spray may also be used to facilitate cooling. "Cook times", rotation speed, temperatures and cooling cycles are computer controlled with appropriate software which also includes a data acquisition system.
Test plaques were cut from the molded cubes. The plaques were exposed to concentrated sulfuric acid (98% H2SO4) at 70 C (As used herein, the term concentrated sulfuric acid refers to a liquid that contains from about 95 to 99% sulfuric acid by weight.
In general, "concentrated sulfuric acid" in commercial use contains about 98%
sulfuric acid).
The comparative compositions discolored after contact with the concentrated sulfuric acid. The following color scale is used to describe increasing levels of discoloration.
0 ¨ White 1 ¨ Tan 2 ¨ Light brown \\chclients\IPGrouo\Scott\SCSoec\2018023.docx 3 ¨ Dark brown/grey 4 - Black Both of the compositions of this example were severely discolored (to black, number 4 on the above scale) after contact with concentrated sulfuric acid at 70 C for 8 days.
\\chclients\IPGroup\ScottISCSnec\2018023.docx Experiment Copolymer MI2 Density HALS
First Secondary Second (g/10 min) (g/cm3) (ppm) Primary AO Primary AO
AO (ppm) (ppm) (ppm) 0 1 SSC1 1.70 0.945 C-944: 750 0 1-168: 550 FS 042: 250 T-622: 750 S-9228: 450 2 ZN1 2.0 0.941 C-3346:2000 1-3114:300 1-168:1200 0 C-944 = Chimassorb 944; T-622 = Tinuvin 622; C-3346 = Cyasorb UV-3346.
1-3114 = Irganox 3114. 1-168 = lrgafos 168; S-9228 = Doverphos S-9228. 5 FS
042 = Irgastabe FS 042;
Both experiments 1 and 2 are comparative because each of the compositions only contained a single primary antioxidant ¨ SSC1 contained only the hydroxylamine (sold under the trademark Irgastab FS042) and ZN1 contained only a phenolic (sold under the tradename Irganox 3114).
\\chclients\IPGroup\Scott\SCSpec\2018023.docx ¨ -Example 2 The formulations shown in Table 2 were used in this example. The rotational molding procedures were similar to those described above except that the molding time was reduced to 34 minutes and the temperature was increased to 480 F. Test plaques were cut from the molded cubes and exposed to concentrated sulfuric acid (98 weight%
H2SO4) at 70 C for the times shown in Table 3. Color values are also presented in Table 3.
The data in Table 3 illustrate that the composition that was prepared with the two different primary antioxidants (namely a phenolic and a hydroxylamine) has improved resistance to discoloration.
\\chclients\IPGrourAScott\SCSDec\2018023.docx 0 Example 2 Formulations 0 Experiment Copolymer MI2 Density HALS
First Secondary Second (g/10 min) (g/cm3) (ppm) Primary AO AO Primary AO
co (ppm) (ppm) (PPrn)
10-C ZN1 2.0 0.941 C-3346: 2000 1-3114: 300 1-168: 1200 0
11-C SS1 1.70 0.945 C-944: 750 0 1-168:550 FS 042: 250 T-622: 750 S-9228: 450
12 SS1 1.70 0.945 C-944: 750 1-1076: 500 1-168: 550 FS 042: 250 T-622: 750 S-9228: 450 C-944 = Chimassorb 944; T-622 = Tinuvin 622; C-3346 = Cyasorb UV-3346. 41-1076 = Irganox 1076; 1-3114 = Irganox 3114. 51-168 =
Irgafos 168; S-9228 = Doverphos S-9228. 6 FS 042 = Irgastab FS 042.
The composition of experiment 10 also contained 450 ppm of zinc stearate. The compositions of experiments 11-13 also contained 750 ppm of zinc oxide.
\\chclients\IPGroup\Scott\SCSpec\2018023.docx Color Values for Inside Surface of Parts Experiment Exposure Time min min days days 0 0 0.5 1 0 0 0 0.5 \\chclients\IPGrotin\Scoff\SCSnec\2018023.docx
Irgafos 168; S-9228 = Doverphos S-9228. 6 FS 042 = Irgastab FS 042.
The composition of experiment 10 also contained 450 ppm of zinc stearate. The compositions of experiments 11-13 also contained 750 ppm of zinc oxide.
\\chclients\IPGroup\Scott\SCSpec\2018023.docx Color Values for Inside Surface of Parts Experiment Exposure Time min min days days 0 0 0.5 1 0 0 0 0.5 \\chclients\IPGrotin\Scoff\SCSnec\2018023.docx
Claims (8)
1. A method for improving the discoloration resistance of a rotational molded polyethylene container that is contacted with concentrated sulfuric acid, said method comprising the steps of 1) providing a stabilized ethylene copolymer composition, wherein said stabilized ethylene copolymer composition contains an additive package comprising A.1) a hindered phenolic primary antioxidant;
A.2) a hydroxylamine primary antioxidant;
B) a phosphite secondary antioxidant;
C) a hindered amine light stabilizer; and 2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container;
and 3) contacting said rotational molded polyethylene container with concentrated sulfuric acid to produce an acid contacted container; wherein said acid contacted container has improved color in comparison to a control acid contacted container that is prepared using an additive package that does not contain any of said hydroxylamine primary antioxidant.
A.2) a hydroxylamine primary antioxidant;
B) a phosphite secondary antioxidant;
C) a hindered amine light stabilizer; and 2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container;
and 3) contacting said rotational molded polyethylene container with concentrated sulfuric acid to produce an acid contacted container; wherein said acid contacted container has improved color in comparison to a control acid contacted container that is prepared using an additive package that does not contain any of said hydroxylamine primary antioxidant.
2. The method of claim 1 wherein said ethylene copolymer composition has a melt index, 12, of from 1 to 10 grams per 10 minutes.
3. The method of claim 1 wherein said ethylene copolymer composition has a density of from 0.93 to 0.95 grams per cubic centimeter.
4. The method of claim 1 wherein said rotational molding conditions included a molding temperature of from 230 to 350°C and a heated molded time of from 10 to 60 minutes.
5. The method of claim 1 wherein said ethylene copolymer composition is prepared from a catalyst type selected from the group consisting of single site catalysts; Ziegler Natta catalysts and combinations thereof.
6. The method of claim 5 wherein said catalyst type consists essentially of at least one single site catalyst.
7. The method of claim 1 wherein said additive package consists essentially of A.1) at least one hindered phenolic primary antioxidant;
A.2) at least one hydroxylamine primary antioxidant;
B) at least one phosphite secondary antioxidant; and C) at least one hindered amine light stabilizer.
A.2) at least one hydroxylamine primary antioxidant;
B) at least one phosphite secondary antioxidant; and C) at least one hindered amine light stabilizer.
8. The method of claim 7 wherein said additive package consists essentially of:
A.1) from 300 to 1500 ppm of at least one hindered phenolic primary antioxidant;
A.2) from 100 to 1000 ppm of at least one hydroxylamine primary antioxidant;
B) from 500 to 2000 ppm of at least one phosphite secondary antioxidant; and C) from 500 to 5000 ppm of at least one hindered amine light stabilizer.
A.1) from 300 to 1500 ppm of at least one hindered phenolic primary antioxidant;
A.2) from 100 to 1000 ppm of at least one hydroxylamine primary antioxidant;
B) from 500 to 2000 ppm of at least one phosphite secondary antioxidant; and C) from 500 to 5000 ppm of at least one hindered amine light stabilizer.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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CA3011044A CA3011044A1 (en) | 2018-07-12 | 2018-07-12 | Acid resistant polyethylene containers |
MX2021000269A MX2021000269A (en) | 2018-07-12 | 2019-07-09 | Acid resistant polyethylene containers. |
BR112021000483-1A BR112021000483A2 (en) | 2018-07-12 | 2019-07-09 | ACID RESISTANT POLYETHYLENE CONTAINERS |
PCT/IB2019/055842 WO2020012358A1 (en) | 2018-07-12 | 2019-07-09 | Acid resistant polyethylene containers |
Applications Claiming Priority (1)
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CA3011044A CA3011044A1 (en) | 2018-07-12 | 2018-07-12 | Acid resistant polyethylene containers |
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CA3011044A1 true CA3011044A1 (en) | 2020-01-12 |
Family
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Family Applications (1)
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CA3011044A Pending CA3011044A1 (en) | 2018-07-12 | 2018-07-12 | Acid resistant polyethylene containers |
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BR (1) | BR112021000483A2 (en) |
CA (1) | CA3011044A1 (en) |
MX (1) | MX2021000269A (en) |
WO (1) | WO2020012358A1 (en) |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
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NL126685C (en) | 1959-08-28 | |||
CA849081A (en) | 1967-03-02 | 1970-08-11 | Du Pont Of Canada Limited | PRODUCTION OF ETHYLENE/.alpha.-OLEFIN COPOLYMERS OF IMPROVED PHYSICAL PROPERTIES |
US5324800A (en) | 1983-06-06 | 1994-06-28 | Exxon Chemical Patents Inc. | Process and catalyst for polyolefin density and molecular weight control |
DE3871854D1 (en) | 1987-05-05 | 1992-07-16 | Ciba Geigy Ag | STABILIZATION OF ORGANIC POLYMERS AGAINST LIGHT DEGRADATION. |
IT1215455B (en) | 1987-05-05 | 1990-02-14 | Ciba Geigy Spa | STABILIZING COMPOSITION FOR POLYETHYLENE INCLUDING COMPOUNDS CONTAINING PIPERIDINIC GROUPS AND METALLIC COMPOUNDS |
US5064802A (en) | 1989-09-14 | 1991-11-12 | The Dow Chemical Company | Metal complex compounds |
US5367025A (en) | 1991-10-08 | 1994-11-22 | Wedtech, (Usa) Inc. | Crosslinkable polyethylene-based composition for rotational molding |
US5530055A (en) | 1994-12-09 | 1996-06-25 | Needham; Donald G. | Nucleated polyolefin-based composition for rotational molding |
US5844029A (en) | 1995-09-25 | 1998-12-01 | General Electric Company | Polymer compositions containing hydrocarbon amine oxide and hydrocarbon amine oxide stabilizer compositions |
CA2245375C (en) | 1998-08-19 | 2006-08-15 | Nova Chemicals Ltd. | Dual reactor polyethylene process using a phosphinimine catalyst |
CA2435986C (en) * | 2003-07-24 | 2011-08-30 | Nova Chemicals Corporation | Rotomolding process with reduced cycle times |
JP2006299062A (en) * | 2005-04-20 | 2006-11-02 | Nippon Polyethylene Kk | Polyethylene resin for container to store sulfuric acid and container made of the same |
CA3044047C (en) * | 2016-11-18 | 2021-03-09 | Equistar Chemicals, Lp | Polyolefin materials for rotational molding applications having improved impact properties and color stability |
-
2018
- 2018-07-12 CA CA3011044A patent/CA3011044A1/en active Pending
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2019
- 2019-07-09 WO PCT/IB2019/055842 patent/WO2020012358A1/en active Application Filing
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