EP2838948A1 - Nucleating agents for polypropylene and propylene copolymers - Google Patents
Nucleating agents for polypropylene and propylene copolymersInfo
- Publication number
- EP2838948A1 EP2838948A1 EP13717273.0A EP13717273A EP2838948A1 EP 2838948 A1 EP2838948 A1 EP 2838948A1 EP 13717273 A EP13717273 A EP 13717273A EP 2838948 A1 EP2838948 A1 EP 2838948A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ester
- polypropylene
- compounds
- polymer
- compound
- 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.)
- Withdrawn
Links
- 239000004743 Polypropylene Substances 0.000 title claims abstract description 93
- 229920001155 polypropylene Polymers 0.000 title claims abstract description 92
- -1 polypropylene Polymers 0.000 title claims abstract description 62
- 239000002667 nucleating agent Substances 0.000 title claims description 105
- 229920001577 copolymer Polymers 0.000 title claims description 14
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 title claims description 11
- 150000001875 compounds Chemical class 0.000 claims abstract description 81
- 238000002425 crystallisation Methods 0.000 claims abstract description 57
- 230000008025 crystallization Effects 0.000 claims abstract description 57
- 229920005606 polypropylene copolymer Polymers 0.000 claims abstract description 35
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 29
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 25
- 125000001931 aliphatic group Chemical group 0.000 claims abstract description 17
- 150000002148 esters Chemical class 0.000 claims abstract description 16
- YIKSCQDJHCMVMK-UHFFFAOYSA-N Oxamide Chemical group NC(=O)C(N)=O YIKSCQDJHCMVMK-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229920000642 polymer Polymers 0.000 claims description 75
- 238000002844 melting Methods 0.000 claims description 40
- 230000008018 melting Effects 0.000 claims description 40
- 238000001816 cooling Methods 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 12
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- 239000002131 composite material Substances 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 238000000465 moulding Methods 0.000 claims description 4
- 125000004185 ester group Chemical group 0.000 abstract description 2
- 238000010899 nucleation Methods 0.000 description 16
- 230000006911 nucleation Effects 0.000 description 16
- 239000000047 product Substances 0.000 description 16
- 238000000113 differential scanning calorimetry Methods 0.000 description 9
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 8
- 229920005653 propylene-ethylene copolymer Polymers 0.000 description 8
- 125000003118 aryl group Chemical group 0.000 description 7
- 239000011159 matrix material Substances 0.000 description 7
- 239000000178 monomer Substances 0.000 description 7
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 150000001408 amides Chemical group 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 125000004122 cyclic group Chemical group 0.000 description 5
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 5
- 238000003786 synthesis reaction Methods 0.000 description 5
- 238000005160 1H NMR spectroscopy Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000000399 optical microscopy Methods 0.000 description 4
- 229920000098 polyolefin Polymers 0.000 description 4
- YWEWWNPYDDHZDI-JJKKTNRVSA-N (1r)-1-[(4r,4ar,8as)-2,6-bis(3,4-dimethylphenyl)-4,4a,8,8a-tetrahydro-[1,3]dioxino[5,4-d][1,3]dioxin-4-yl]ethane-1,2-diol Chemical compound C1=C(C)C(C)=CC=C1C1O[C@H]2[C@@H]([C@H](O)CO)OC(C=3C=C(C)C(C)=CC=3)O[C@H]2CO1 YWEWWNPYDDHZDI-JJKKTNRVSA-N 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 3
- 150000001335 aliphatic alkanes Chemical group 0.000 description 3
- 125000003368 amide group Chemical group 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- KWKRTNFTBCZAGB-UHFFFAOYSA-N n'-phenyloxamide Chemical compound NC(=O)C(=O)NC1=CC=CC=C1 KWKRTNFTBCZAGB-UHFFFAOYSA-N 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 229920002959 polymer blend Polymers 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XOJVVFBFDXDTEG-UHFFFAOYSA-N Norphytane Natural products CC(C)CCCC(C)CCCC(C)CCCC(C)C XOJVVFBFDXDTEG-UHFFFAOYSA-N 0.000 description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric Acid Chemical compound [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 description 2
- 150000002430 hydrocarbons Chemical group 0.000 description 2
- 125000001570 methylene group Chemical group [H]C([H])([*:1])[*:2] 0.000 description 2
- CYTDFPBARASFSI-UHFFFAOYSA-N n-hexyl-n'-[2-[[2-(hexylamino)-2-oxoacetyl]amino]ethyl]oxamide Chemical compound CCCCCCNC(=O)C(=O)NCCNC(=O)C(=O)NCCCCCC CYTDFPBARASFSI-UHFFFAOYSA-N 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 125000006850 spacer group Chemical group 0.000 description 2
- 239000004753 textile Substances 0.000 description 2
- 238000002076 thermal analysis method Methods 0.000 description 2
- DTQVDTLACAAQTR-DYCDLGHISA-N trifluoroacetic acid-d1 Chemical compound [2H]OC(=O)C(F)(F)F DTQVDTLACAAQTR-DYCDLGHISA-N 0.000 description 2
- 239000004711 α-olefin Substances 0.000 description 2
- FMZUHGYZWYNSOA-VVBFYGJXSA-N (1r)-1-[(4r,4ar,8as)-2,6-diphenyl-4,4a,8,8a-tetrahydro-[1,3]dioxino[5,4-d][1,3]dioxin-4-yl]ethane-1,2-diol Chemical compound C([C@@H]1OC(O[C@@H]([C@@H]1O1)[C@H](O)CO)C=2C=CC=CC=2)OC1C1=CC=CC=C1 FMZUHGYZWYNSOA-VVBFYGJXSA-N 0.000 description 1
- ZWVMLYRJXORSEP-LURJTMIESA-N (2s)-hexane-1,2,6-triol Chemical compound OCCCC[C@H](O)CO ZWVMLYRJXORSEP-LURJTMIESA-N 0.000 description 1
- ZVHQFRVSLFEGFT-UHFFFAOYSA-N 1-N',9-N'-di(heptanoyl)nonanedihydrazide Chemical compound C(CCCCCC)(=O)NNC(CCCCCCCC(=O)NNC(CCCCCC)=O)=O ZVHQFRVSLFEGFT-UHFFFAOYSA-N 0.000 description 1
- BMVXCPBXGZKUPN-UHFFFAOYSA-N 1-hexanamine Chemical compound CCCCCCN BMVXCPBXGZKUPN-UHFFFAOYSA-N 0.000 description 1
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical group C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 1
- 229920000089 Cyclic olefin copolymer Polymers 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 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 1
- RHCNSLAGXVMZTN-UHFFFAOYSA-N N'-(4,6-dimethylheptan-2-yl)oxamide Chemical compound CC(CC(C)NC(C(=O)N)=O)CC(C)C RHCNSLAGXVMZTN-UHFFFAOYSA-N 0.000 description 1
- UWUKDMKMUGNLAR-UHFFFAOYSA-N N-decyl-N'-[2-[[2-(decylamino)-2-oxoacetyl]amino]ethyl]oxamide Chemical compound C(CNC(C(=O)NCCCCCCCCCC)=O)NC(C(=O)NCCCCCCCCCC)=O UWUKDMKMUGNLAR-UHFFFAOYSA-N 0.000 description 1
- YEFLLIBHMUPRGG-UHFFFAOYSA-N N-hexadecyl-N'-[2-[[2-(hexadecylamino)-2-oxoacetyl]amino]ethyl]oxamide Chemical compound C(CNC(C(=O)NCCCCCCCCCCCCCCCC)=O)NC(C(=O)NCCCCCCCCCCCCCCCC)=O YEFLLIBHMUPRGG-UHFFFAOYSA-N 0.000 description 1
- JDCGUIMDZMKKMZ-UHFFFAOYSA-N N-hexyl-N'-[6-[[2-(hexylamino)-2-oxoacetyl]amino]hexyl]oxamide Chemical compound C(CCCCCNC(C(=O)NCCCCCC)=O)NC(C(=O)NCCCCCC)=O JDCGUIMDZMKKMZ-UHFFFAOYSA-N 0.000 description 1
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229920011250 Polypropylene Block Copolymer Polymers 0.000 description 1
- 102000001708 Protein Isoforms Human genes 0.000 description 1
- 108010029485 Protein Isoforms Proteins 0.000 description 1
- PHMHDRYYFAYWEG-UHFFFAOYSA-N Rhapontigenin Natural products C1=C(O)C(OC)=CC=C1C=CC1=CC(O)=CC(O)=C1 PHMHDRYYFAYWEG-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 125000006852 aliphatic spacer Chemical group 0.000 description 1
- 125000006295 amino methylene group Chemical group [H]N(*)C([H])([H])* 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000004630 atomic force microscopy Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- FQUNFJULCYSSOP-UHFFFAOYSA-N bisoctrizole Chemical compound N1=C2C=CC=CC2=NN1C1=CC(C(C)(C)CC(C)(C)C)=CC(CC=2C(=C(C=C(C=2)C(C)(C)CC(C)(C)C)N2N=C3C=CC=CC3=N2)O)=C1O FQUNFJULCYSSOP-UHFFFAOYSA-N 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 125000002704 decyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 229940087101 dibenzylidene sorbitol Drugs 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- JZMQHGGFCBIHNG-UHFFFAOYSA-N ethyl 2-[2-[(2-ethoxy-2-oxoacetyl)amino]ethylamino]-2-oxoacetate Chemical compound CCOC(=O)C(=O)NCCNC(=O)C(=O)OCC JZMQHGGFCBIHNG-UHFFFAOYSA-N 0.000 description 1
- YDGAUBHNAKCSKF-UHFFFAOYSA-N ethyl 2-anilino-2-oxoacetate Chemical compound CCOC(=O)C(=O)NC1=CC=CC=C1 YDGAUBHNAKCSKF-UHFFFAOYSA-N 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000012994 industrial processing Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- IZNQTDOEMFBMIH-UHFFFAOYSA-N n'-decyloxamide Chemical compound CCCCCCCCCCNC(=O)C(N)=O IZNQTDOEMFBMIH-UHFFFAOYSA-N 0.000 description 1
- ZTLAAOOAIBVFNM-UHFFFAOYSA-N n'-hexyloxamide Chemical compound CCCCCCNC(=O)C(N)=O ZTLAAOOAIBVFNM-UHFFFAOYSA-N 0.000 description 1
- QZLPDBKEVWFQNF-UHFFFAOYSA-N n,n'-diphenylhexanediamide Chemical compound C=1C=CC=CC=1NC(=O)CCCCC(=O)NC1=CC=CC=C1 QZLPDBKEVWFQNF-UHFFFAOYSA-N 0.000 description 1
- FTQWRYSLUYAIRQ-UHFFFAOYSA-N n-[(octadecanoylamino)methyl]octadecanamide Chemical class CCCCCCCCCCCCCCCCCC(=O)NCNC(=O)CCCCCCCCCCCCCCCCC FTQWRYSLUYAIRQ-UHFFFAOYSA-N 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- UMRZSTCPUPJPOJ-KNVOCYPGSA-N norbornane Chemical compound C1C[C@H]2CC[C@@H]1C2 UMRZSTCPUPJPOJ-KNVOCYPGSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229920001748 polybutylene Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000306 polymethylpentene Polymers 0.000 description 1
- 239000011116 polymethylpentene Substances 0.000 description 1
- 229920005629 polypropylene homopolymer Polymers 0.000 description 1
- 229920005630 polypropylene random copolymer Polymers 0.000 description 1
- TVTYHZLXPFUGOO-UHFFFAOYSA-N propane-1,1,1-tricarboxamide Chemical class CCC(C(N)=O)(C(N)=O)C(N)=O TVTYHZLXPFUGOO-UHFFFAOYSA-N 0.000 description 1
- LRGQZEKJTHEMOJ-UHFFFAOYSA-N propane-1,2,3-triol;zinc Chemical compound [Zn].OCC(O)CO LRGQZEKJTHEMOJ-UHFFFAOYSA-N 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 230000003678 scratch resistant effect Effects 0.000 description 1
- 238000001338 self-assembly Methods 0.000 description 1
- WXMKPNITSTVMEF-UHFFFAOYSA-M sodium benzoate Chemical compound [Na+].[O-]C(=O)C1=CC=CC=C1 WXMKPNITSTVMEF-UHFFFAOYSA-M 0.000 description 1
- 235000010234 sodium benzoate Nutrition 0.000 description 1
- 239000004299 sodium benzoate Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000000600 sorbitol Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 125000001424 substituent group Chemical group 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
Classifications
-
- 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
- C08K5/20—Carboxylic acid amides
Definitions
- polyolefins are very popular materials.
- the main factors responsible for the growth in polyolefins consumption are the inherent versatility of these polymers and the ease with which they can be processed.
- the properties and the morphology of the semi-crystalline polyolefins mainly depend on the molecular structure, processing additives and the processing conditions.
- polypropylene is a thermoplastic polymer which is employed for a large variety of different products: ranging from packaging products, textiles, stationery, plastic parts and reusable containers of various types, laboratory equipment to automotive components.
- PP consists basically of a sequence of propylene monomers, where a methylene group is present as side group on every other carbon atom in the backbone chain.
- PP is classified into three different subgroups as atactic PP (aPP), isotactic PP (iPP) and syndiotactic PP (sPP).
- aPP the side groups are randomly distributed, which results in amorphous, rubbery materials.
- iPP has side groups consistently on one side, offering long range order for crystallization. While in the case of sPP, the side groups are distributed in alternating fashion along the backbone.
- Isotactic polypropylene is the isoform mainly used commercially. Main drawbacks in the use of PP are its low nucleation density and slow crystallization rate. To improve these disadvantages nucleating agents are used for the crystallization of polypropylene.
- sorbitol compounds as e.g. dibenzylidene sorbitol which is disclosed in US40161 18.
- US2010317779 teaches a composition of scratch resistant polypropylene which is produced with a nucleating agent selected from the group consisting of sodium benzoate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate, zinc glycerolate, calcium salt of 1 ,2-dicarboxylic acid cyclohexane and sodium salt of 1 ,2- dicarboxylic acid norbornane.
- a nucleating agent selected from the group consisting of sodium benzoate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate, zinc glycerolate, calcium salt of 1 ,2-dicarboxylic acid cyclohexane and sodium salt of 1 ,2- dicarboxylic acid norbornane.
- a nucleating agent selected from the group consisting of sodium benzoate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl)
- US201 1 13101330 discloses a polypropylene resin composition
- a polypropylene resin composition comprising an polypropylene polyethylene copolymer and an amide compound as nucleating agent.
- the amide groups are substituents of an aromatic ring or in the form of a propane tricarboxylic acid triamide.
- EP0557721 and EP1431335 describe bisamide compounds for the crystallization of polypropylene.
- the combination of nucleation efficiency, decrease in crystallization half-time, and desired transparency of the product in the presence of the nucleating agents is not optimal in prior art.
- the aim of present invention is to overcome at least in part the disadvantages that lie in the use of known nucleating agents and to provide alternative nucleating agents for polypropylene and polypropylene copolymers.
- the present invention suggests to use a class of compounds as nucleating agents for polypropylene and polypropylene copolymers, which compounds have high nucleation efficiency and a melting temperature which can be adjusted to the melting temperature of the specific polypropylene or polypropylene copolymers. Also, due to the use of the nucleating agents the half- time of crystallization of the polymer is decreased.
- the nucleating agents of present invention allow for a high onset crystallization temperature and high degree of crystallinity. Additionally, the inventive use of the nucleating agents results in good transparency and structural order of the polypropylene or polypropylene copolymers.
- Another objective of this invention is to provide a process for crystallization of polypropylene or polypropylene copolymers wherein the nucleating agent has high nucleation efficiency.
- compositions of polypropylene or polypropylene copolymer and nucleating agents with high nucleation efficiency are provided and films, moldings, composite materials, extrusion- or injection-molded products or elongated products comprising the composition.
- each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
- X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms
- Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
- Oxalamide and bisoxalamide compounds are known (Deshmukh S. et al., PMSE Preprints, American Chemical Society, 201 1 , vol. 104, p. 343-345) However, it is surprising that these compounds present such efficient nucleating agents for polypropylene and polypropylene copolymers.
- EP0421377 shows that unsymmetric bisoxalamides substituted with aromatic moieties in the center or in the side arms are used as nucleating agents for polyethylene terephthalates.
- polypropylene includes no aromatic or cyclic moieties.
- the flexible side arms of the nucleating agents and the flexible bridging motifs between the oxalamides, disclosed in this application, will enhance the aggregation process prior to crystallization of the polypropylene or polypropylene copolymer.
- the similarity of the chemical structure of the side arms with the chemical structure of polypropylene will ensure a proper dissolution and a homogeneous distribution in the polymer melt.
- At least one of the side arms R and R' is chosen from an alkyl group with a total carbon number between 2 and 20, preferably with a total carbon number between 4 and 10 and more preferably with a total carbon number between 6 and 8.
- hydrocarbon group and/or on the alkyl side arms R or R' are substituted by methyl, ethyl or alkyl groups of up to 8 carbon atoms, where the total number of all carbon atoms of the saturated aliphatic hydrocarbon group or the alkyl group is not higher than 20.
- at least one of the arms R or R' comprises a branched alkyl group and/or a branched saturated aliphatic
- An ester is a group containing a carbonyl connected to an oxygen atom (-C(O)-O-) or an oxygen atom connected to a carbonyl group (-O-C(O)-).
- the saturated aliphatic hydrocarbon group (referred to as X) comprising 1 to 20 carbon atoms is part of an alkane chain and only consists of carbon and hydrogen atoms. All carbons are bound to each other by single carbon bonds.
- X includes unbranched carbon chains and branched carbon chains, i.e. isomers where the total number of carbon atoms is limited to 20.
- the saturated aliphatic hydrocarbon group is bound to the other moieties of the nucleating agent by two bonds.
- Examples of the aliphatic hydrocarbon group are: -CH 2 -CH 2 -CH 2 - or -CH 2 (CH 3 )- CH 2 -.
- the saturated aliphatic hydrocarbon group is bound to a methyl group or H (i.e. Y) on one side and to an ester group or the bisoxalamide motif, i.e. the core of the nucleating agent on the other side.
- alkyl is an aliphatic moiety with a total number of carbon atoms between 1 and 20, i.e. a functional group comprising only carbon and hydrogen atoms derived from an alkane by removing one hydrogen atom. This definition includes
- NA3 N ⁇ N'-iethane-l ,2-diyl)bis(N 2 -decyloxalamide)
- NA4 ⁇ ', ⁇ ' -(ethane- 1 ,2-d j;i,y,n 1 )ub;is n a(.V;2 " - exadec loxalamide)
- the following compounds are also nucleating agents according to present invention. These non-limiting examples include compounds with symmetric arms (R is identical to R') , as e.g.:
- the core motif comprises two oxalamide motifs.
- Amide motifs are hydrogen bonding motifs. They are the driving force for crystallization of the polymer. Because multiple amide motifs are present in the compound the hydrogen bonding is very strong. The hydrogen bonding leads to self-assembly of compound molecules, which form long needle-like structures that act as nucleating agent for the polymer.
- the different length of the alkyl moiety influences the peak melting and crystallization temperature of the compound in such a manner that a longer alkyl chain or spacer decreases the melting temperature while a shorter spacer increases the melting temperature (Table 1 ). Compare e.g. NA2 and NA5 in table 1 .
- the length of the aliphatic spacer can be used as a tool to design the optimal compound for a specific polymer matrix in terms of its solubility and melting temperature.
- Control of the melting point is useful to use the compound or a combination of compounds as efficient nucleating agent with polypropylene or different polypropylene copolymers which have a range of melting temperatures.
- the nucleating agents according to present invention have peak melting temperatures ranging from 150 to 300°C.
- N 1 ,N 1 -(hexane-1 ,6- diyl)bis(N 2 -phenyloxalamide) has a peak melting temperature of 272°C.
- the tunable melting temperature of the compounds is an advantage of the present invention over nucleating agents known previously.
- the high melting temperature of the compounds is an advantage over previously known nucleating agents.
- the high melting temperature that arises due to strong hydrogen bonding results in a very high nudeation efficiency of the nucleating agent. It also allows for the use of the compound or a combination of compounds as nudeation agent for polymers with a tailored melting temperature. For example, 100% iPP has an approximate peak melting temperature of 166°C, while a 93% propylene / 7% ethylene copolymer has a peak melting temperature of 140°C approximately.
- the peak melting temperature (or dissolution temperature) of the nucleating agent decreases when mixed with the polymer.
- the decrease in the peak melting temperature (T m ) and peak crystallization temperature (T c ) of the nucleating agent when mixed with polypropylene shows its good miscibility in the polymer melt (Table 2).
- Table 2 Crystallization of NA2 in a PP matrix.
- the arms R and R' can be chosen in a way to improve the miscibility with the polymer.
- a good miscibility of the nucleating agent with the polymer causes a homogenous distribution of the nucleating agent in the polymer matrix and leads to better crystallization. This is obtained by designing the arms to be similar to the molecular configuration of the polymer.
- R, R' and the molecular configuration of the polymer to be crystallized are similar, the crystal structure of the compound suppresses the nucleation barrier and increases the nucleation efficiency of the polymer, thus increasing the crystallization rate.
- flanking arms are independently of each other chosen from:
- X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms
- Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
- the nucleating agents according to present invention can be used to crystallize polypropylene polymer and polypropylene copolymers.
- polypropylene includes isotactic, syndiotactic and atactic polypropylene, where the tacticity can vary from approximately 60 to 100% in the case of isotactic and syndiotactic polypropylenes.
- Polypropylene copolymers for the purpose of this invention include polypropylene- alpha-olefin copolymers and poly(propylene-styrene) copolymers.
- suitable alpha-olefins include but are not limited to polyethylene (PE), polybutylene, and poly(4-methyl-1 -pentene).
- the polypropylene copolymers include polypropylene block copolymers and polypropylene random copolymers.
- the polypropylene copolymers comprise at least 60% propylene units.
- a preferred polypropylene copolymer is a propylene-ethylene copolymer, where e.g. the amount of ethylene monomers varies between 1 and 10 mole% based on the total amounts of monomers which are used to produce the polymer, preferably between 2 and 5 mole%.
- one compound according to the invention can be used to crystallize polypropylene and polypropylene copolymers.
- a combination of compounds according to present invention is used to crystallize polypropylene or polypropylene copolymers.
- the compound or the combination of compounds are applied at a concentration of 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2-0.5wt% based on the weight of the polypropylene or propylene copolymer.
- a combination of compounds is used to crystallize polypropylene or polypropylene copolymers, said amounts refer to the combined amount of the different compounds.
- the total amount of nucleating agent added to the polymer can either consists of one nucleating agent or a combination of different nucleating agents according to this invention. If a combination of nucleating agents is used, the total amount of nucleating agents is the same as if one nucleating agent is used. The amount is always based on the weight of the polymer or copolymer. For example, 0.05wt% of nucleating agent A and 0.05wt% of nucleating agent B result in an amount of 0.1 wt% nucleating agent based on the weight of the polymer.
- each compound of such a combination of compounds can vary depending on the polymer, copolymer or polymer mixture which is to be crystallized.
- the invention relates to a process for crystallization of polypropylene or polypropylene copolymer, comprising the steps of:
- each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
- X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms
- Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
- a fine needle-like morphology of the nucleating agents can be observed and the polymer starts crystallizing from the surface of the nucleating agent.
- the presence of the fine needle-like morphology of the nucleating agent enhances the nucleation efficiency of the polymer in comparison with a polymer without nucleating agents.
- the dimensions of the needle-like crystals vary with the crystallization conditions and the chosen combinations of the nucleating agents. With smaller crystal size the surface area of the nucleation site is increased which improves the crystallization and nucleation efficiency.
- the nucleating agents of present invention have a crystal size in the polymer matrix of up to 50 micrometer ( ⁇ ).
- the crystal size is below several hundreds of nanometer (nm), e.g. between 10 and 750 nm, more preferably between 50 and 500 nm, even more preferably between 100 and 250 nm.
- the crystal size of the nucleating agent in the polymer matrix can be determined by optical microscopy or electron microscopy or atomic force microscopy.
- the nucleating agents according to the invention show high nucleation efficiencies.
- the nucleation efficiency (NE) is defined as the increase of the crystallization temperature of the polymer with the nucleating agent compared to the crystallization temperature without nucleating agent. This is calculated by using equation 1 :
- T NE (T c - T cl )/(r c2max - T el ) x 100% , where T c i and T C 2max are the peak crystallization temperatures of the non- nucleated and self-nucleated polymer, respectively. T c is the peak crystallization temperature of the polymer with the nucleating agents.
- Polypropylene and polypropylene copolymers crystallize inefficiently without a nucleating agent in industrial processing.
- the material which can be obtained without nucleating agent is of lower crystallinity and has a lower dimensional stability.
- the onset temperature for crystallization of the polymer is increased.
- the here described nucleating agents or combinations thereof increase the onset crystallization temperature by at least 5°C, preferably by at least 10°C, more preferably by at least 15°C, or by at least 20°C compared to the polymer or copolymer without any nucleating agent.
- the specific temperature depends on the specific compound or combination of compounds according to this invention, the amount of nucleating agent and the polymer or copolymer. A higher onset temperature is better for the produced plastics because the mechanical properties of the material are better, the production time is shorter because less cooling has to take place and no or less shrinkage of the crystallized polymer occurs.
- the high nucleation efficiency provides the desired dimension stability.
- the high onset crystallization temperature of the polymer or copolymer in the presence of the nucleating agents of present invention enables easier processibilty and a higher dimension stability of the polymer product.
- PP or PP copolymers crystallized with nucleating agents according to this invention or a combination of those have a good transparency.
- the temperature at which the polymer and the compound or combination of compounds are mixed ranges between 10°C and 140°C, preferably between 20 and 120°C, more preferably between 40°C and 120°C above the peak melting temperature of the polymer.
- the temperature at which the polymer and the compound or combination of compounds are cooled ranges from about 140°C above the peak melting temperature of the polymer to 20°C, preferably from 120°C above the peak melting temperature of the polymer to 20°C. In one embodiment the polymer and the compound or combination of compounds are cooled at room temperature.
- the cooling occurs at a rate ranging between 1 °C/min and 500°C/min, preferably between 10°C/min and 300°C/min, more preferably between 20°C/min and 100°C /min.
- the invention relates to a composition
- a composition comprising polypropylene or polypropylene copolymer, and a compound or a combination of compounds, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
- X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms
- Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
- the composition comprises 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2- 0.5wt% of the compound or a combination of compounds based on the weight of the polypropylene or propylene copolymer.
- films, moldings, composite materials, injection- or extrusion- molded products or elongated products comprise a composition according to this invention.
- Elongated products include fibers, as e.g. staple fiber and short fiber.
- composition can therefore comprise polypropylene, polypropylene copolymer or a polymer mixture together with one compound or a combination of compounds according to this invention.
- compositions can be used to produce films, moldings, composite materials, injection- or extrusion molded products or elongated products.
- any of said compositions can be used in plastic carrier bags, bottles, food packaging products and textiles.
- a composition according to the invention for bottles and food packaging products because many of the nucleating agents according to present invention are considered non-toxic.
- NA1 and NA2 are described:
- Ethyl oxanilate (5 g, 25.8 mmol) was dissolved in 200 ml of chloroform. 1 ,6- hexamethylenediamine (1 .5 g, 12.9 mmol) was added and the mixture was left to stir under reflux for 48 hours. The formed precipitate was filtered and washed successively with chloroform and diethyl ether before drying in vacuo overnight (80 °C). The product was obtained as a white powder, showed a (1 st ) melting point of 273°C and a crystallization point at 252°C. The compound is thermally stable up to 280 °C.
- melt mixing of the nucleating agent and the polymer was performed using a mini- extruder with sample residence time of 5 min after complete feeding.
- isotactic polypropylene (Sabic, grade 1531 P) or a propylene-ethylene copolymer comprising 5 mole% (Dow, Versify 2000®) or 9 mole% (Dow, Versify 2200®) of ethylene monomers and 95 mole% or 91 mole% of propylene monomers respectively was used as polymer. All samples were prepared using 0- 1 % of a nucleating agent by weight of the polymer. The samples were processed at 230 or 280°C.
- the onset melting temperature is defined as the start of the endothermic process, whereas the peak melting temperature or peak melting point is defined as the peak of the endothermic process recorded by DSC.
- the onset crystallization temperature is defined as the start of the exothermic process, whereas the peak crystallization temperature is defined as the peak of the exothermic process recorded by DSC.
- Crystallization measurements were conducted on a Zeiss Axioplan 2 Imaging optical microscopy under crossed polarizers with a CD achorplan objective (Zoom).
- a THMS 600 heating stage connected to a Linkam TMS 94 control unit was mounted on the optical microscope. Samples were heated to above the melting temperature of the polymer and cooled at a specific cooling rate under nitrogen atmosphere.
- NA1 N 1 ,N 1 -(hexane-1 ,6-diyl)bis(N 2 -phenyloxalamide)
- NA2 N 1 ,N 1 ' -(ethane-1 ,2-diyl)bis(N 2 -hexyloxalamide)
- NA3 N 1 ,N 1 ' -(ethane-1 ,2-diyl)bis(N 2 -decyloxalamide)
- NA4 N 1 ,N 1 '-(ethane-1 ,2-diyl)bis(N 2 -hexadecyloxalamide)
- NA5 N 1 ,N 1 '-(hexane-1 ,6-diyl)bis(N 2 -hexyloxalamide)
- T m Peak melting temperature of the polymer, nucleating agent or polymer in the presence of the nucleating agent (cf. tables 3 and 4)
- T C /T C N Peak crystallization temperature of the polymer in the presence of the nucleating agent (T C N ) or of the pristine polymer (T c )
- Tonset Onset of crystallization temperature of the polymer in the presence of the nucleating agent or of the pristine polymer
- Polypropylene and a varying amount of the nucleating agents NA1 , NA2, NA3, NA4, NA5 or sorbitol (DMDBS) were melt-mixed and processed at 230 or 280°C.
- the cooling rate was set to 10 or 100°C/min.
- a cooling rate of 100°C/min corresponds to conditions similar to those used in industrial production.
- the nucleating efficiencies of the nucleating agents are shown in Table 3.
- the polymer without the nucleating agent crystallizes at 1 13 and 105°C corresponding to the cooling rate of 10 and 100 °C/min, respectively, whereas the polymer in the presence of nucleating agents can crystallize at a range of temperatures (Table 3).
- the nucleating agent NA2 at a concentration of 0.4 and 1 .0wt% showed a very good nudeation efficiency for the polymer matrix at faster (100°C/min) and as well at slower (10°C/min) cooling rates.
- T C 2max is 137.4°C (referred from Journal of Thermal Analysis, 1994, 42, 721 -731 ) and 132.3 ° C (measured by DSC at a cooling rate of 100 °C/min from a partial melt state) for the cooling rate of 10 ° C/min and 100°C/min, respectively.
- N' 1 , N' 9 diheptanoylnonane- dihydrazide (DHNHZ) and N 1 ,N 6 -diphenyladipamide (DPAD) were tested.
- DPAD is a bisamide compound with an aliphatic linker between the amide groups and benzol rings as side arms.
- DHNHZ is a dihydrazide, i.e. the order of the amide groups is inverted when compared to an oxalamide residue.
- T C 2max is 137.4°C (referred from Journal of Thermal Analysis, 1994, 42, 721 -731 ) and 132.3 ° C (measured by DSC at a cooling rate of 100 °C/min from a partial melt state) for the cooling rate of 100°C/min, respectively.
- the bisamide compound known from EP0557721 and EP1431335 (as e.g. DPAD) and the compounds described in EP0421377 comprise amide motifs and cyclic or aromatic groups.
- the nucleating agents of present invention do not comprise cyclic or aromatic groups.
- nucleating agents of the prior art are likely to perturb the aggregation of the amide motifs due to the sterical hindrance of the cyclic or aromatic motifs. This could result in a lower nucleation efficiency when used as nucleating agents for polypropylene or polypropylene copolymers.
- EP0421377 describes the use of such nucleating agents to crystallize polyethylene terephthalates.
- the nucleating agents of present invention are also suited for the crystallization of polypropylene copolymers.
- a propylene-ethylene copolymer (PP-co-PE) comprising 5 mole% (Dow, Versify 2000®) or 9 mole% (Dow, Versify 2200®) of ethylene monomers and 95 mole% or 91 mole% of propylene monomers respectively was used as polymer for the crystallization with NA2.
- No nucleating efficiency can be determined because the maximum crystallinity for the specific mole% of the copolymer will be dependent on the polymerization conditions like catalyst, temperature etc.
- the increase of the T c and T onS et in presence of the nucleating agent indicate that the nucleating agent according to this invention enhances the crystallization temperature of copolymers and promotes crystallization.
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Abstract
Use of a compound or a combination of compounds for crystallization of polypropylene or polypropylene copolymers, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula: R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from: (i) H; (ii) an alkyl group with a total number of carbon atoms between 1 and 20; or (iii) an ester group as e.g. - X-Ester-Y, or - X-Ester- X-Ester-Y, wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an aliphatic alkyl group with a total number of carbon atoms between 1 and 20 Ester is -C(O)-O- or -O-C(O)-.
Description
NUCLEATING AGENTS FOR POLYPROPYLENE AND PROPYLENE
COPOLYMERS
Description:
The interest in semi-crystalline polymeric materials has increased rapidly in recent decades. Among the polymeric materials, polyolefins are very popular materials. The main factors responsible for the growth in polyolefins consumption are the inherent versatility of these polymers and the ease with which they can be processed. The properties and the morphology of the semi-crystalline polyolefins mainly depend on the molecular structure, processing additives and the processing conditions.
One of the widely used polyolefins is polypropylene (PP). The world-wide market volume of polypropylene is expected to grow from 52 mega tons/year in 2008 to 69.1 megatons/year in 2013. Polypropylene is a thermoplastic polymer which is employed for a large variety of different products: ranging from packaging products, textiles, stationery, plastic parts and reusable containers of various types, laboratory equipment to automotive components. PP consists basically of a sequence of propylene monomers, where a methylene group is present as side group on every other carbon atom in the backbone chain. PP is classified into three different subgroups as atactic PP (aPP), isotactic PP (iPP) and syndiotactic PP (sPP). In aPP, the side groups are randomly distributed, which results in amorphous, rubbery materials. In contrast, iPP has side groups consistently on one side, offering long range order for crystallization. While in the case of sPP, the side groups are distributed in alternating fashion along the backbone.
Isotactic polypropylene is the isoform mainly used commercially. Main drawbacks in the use of PP are its low nucleation density and slow crystallization rate. To improve these disadvantages nucleating agents are used for the crystallization of polypropylene.
Nucleating agents for polypropylene are known.
Widely used as nucleating agents for PP are sorbitol compounds, as e.g. dibenzylidene sorbitol which is disclosed in US40161 18.
US2010317779 teaches a composition of scratch resistant polypropylene which is produced with a nucleating agent selected from the group consisting of sodium benzoate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate, zinc glycerolate, calcium salt of 1 ,2-dicarboxylic acid cyclohexane and sodium salt of 1 ,2- dicarboxylic acid norbornane. Also US2010010168 and WO201 1 131 123 describe the use of carboxylate compounds as nucleating agents, the latter in combination with a phosphate-type nucleating agent.
US201 1 13101330 discloses a polypropylene resin composition comprising an polypropylene polyethylene copolymer and an amide compound as nucleating agent. In the nucleating agent the amide groups are substituents of an aromatic ring or in the form of a propane tricarboxylic acid triamide.
EP0557721 and EP1431335 describe bisamide compounds for the crystallization of polypropylene.
The combination of nucleation efficiency, decrease in crystallization half-time, and desired transparency of the product in the presence of the nucleating agents is not optimal in prior art.
The aim of present invention is to overcome at least in part the disadvantages that lie in the use of known nucleating agents and to provide alternative nucleating agents for polypropylene and polypropylene copolymers.
To achieve this, the present invention suggests to use a class of compounds as nucleating agents for polypropylene and polypropylene copolymers, which compounds have high nucleation efficiency and a melting temperature which can be adjusted to the melting temperature of the specific polypropylene or polypropylene copolymers. Also, due to the use of the nucleating agents the half- time of crystallization of the polymer is decreased. The nucleating agents of present invention allow for a high onset crystallization temperature and high degree of crystallinity. Additionally, the inventive use of the nucleating agents results in good transparency and structural order of the polypropylene or polypropylene copolymers.
Another objective of this invention is to provide a process for crystallization of polypropylene or polypropylene copolymers wherein the nucleating agent has high nucleation efficiency.
Furthermore, a composition of polypropylene or polypropylene copolymer and nucleating agents with high nucleation efficiency are provided and films, moldings, composite materials, extrusion- or injection-molded products or elongated products comprising the composition.
Throughout this description the terms 'nucleating agent' and 'compound' are used interchangeably.
These tasks are solved by using a compound or a combination of compounds for crystallization of polypropylene or polypropylene copolymers, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
Oxalamide and bisoxalamide compounds are known (Deshmukh S. et al., PMSE Preprints, American Chemical Society, 201 1 , vol. 104, p. 343-345) However, it is surprising that these compounds present such efficient nucleating agents for polypropylene and polypropylene copolymers. EP0421377 shows that unsymmetric bisoxalamides substituted with aromatic moieties in the center or in the side arms are used as nucleating agents for polyethylene terephthalates. However, polypropylene includes no aromatic or cyclic moieties.
The flexible side arms of the nucleating agents and the flexible bridging motifs between the oxalamides, disclosed in this application, will enhance the aggregation process prior to crystallization of the polypropylene or polypropylene copolymer. The similarity of the chemical structure of the side arms with the chemical structure of polypropylene will ensure a proper dissolution and a homogeneous distribution in the polymer melt.
In one embodiment at least one of the side arms R and R' is chosen from an alkyl group with a total carbon number between 2 and 20, preferably with a total carbon
number between 4 and 10 and more preferably with a total carbon number between 6 and 8.
In another embodiment the hydrogen atoms on the saturated aliphatic
hydrocarbon group and/or on the alkyl side arms R or R' are substituted by methyl, ethyl or alkyl groups of up to 8 carbon atoms, where the total number of all carbon atoms of the saturated aliphatic hydrocarbon group or the alkyl group is not higher than 20. This means that in this embodiment at least one of the arms R or R' comprises a branched alkyl group and/or a branched saturated aliphatic
hydrocarbon group.
An ester is a group containing a carbonyl connected to an oxygen atom (-C(O)-O-) or an oxygen atom connected to a carbonyl group (-O-C(O)-).
The saturated aliphatic hydrocarbon group (referred to as X) comprising 1 to 20 carbon atoms is part of an alkane chain and only consists of carbon and hydrogen atoms. All carbons are bound to each other by single carbon bonds. X includes unbranched carbon chains and branched carbon chains, i.e. isomers where the total number of carbon atoms is limited to 20.
The saturated aliphatic hydrocarbon group is bound to the other moieties of the nucleating agent by two bonds.
Examples of the aliphatic hydrocarbon group are: -CH2-CH2-CH2- or -CH2(CH3)- CH2-.
For example, the saturated aliphatic hydrocarbon group is bound to a methyl group or H (i.e. Y) on one side and to an ester group or the bisoxalamide motif, i.e. the core of the nucleating agent on the other side.
An alkyl is an aliphatic moiety with a total number of carbon atoms between 1 and 20, i.e. a functional group comprising only carbon and hydrogen atoms derived from an alkane by removing one hydrogen atom. This definition includes
unbranched carbon chains and branched carbon chains, i.e. isomers.
Examples are: methyl, ethyl, propyl or isopropyl.
For example one compound according to the invention has the following structural formula:
NA2: JY ,N -(ethane- l,2-diyl)bis(N -hexyloxalamide)
In another embodiment the structural formula can be:
NA3: N^N'-iethane-l ,2-diyl)bis(N2-decyloxalamide)
Or:
NA4: Ν',Ν' -(ethane- 1 ,2-d j;i,y,n 1 )ub;isna(.V;2" - exadec loxalamide)
NA5: N ,N - exane-l,6- y siV - exyoxaam e
The following compounds are also nucleating agents according to present invention. These non-limiting examples include compounds with symmetric arms (R is identical to R') , as e.g.:
N1 ,N] -{ hexane- 1 ,6-diy I )bis( Λ : -( undecaii-6-y! (oxalamide)
N^N1 '-(hexane- l,6-diyl)bis(N2-(4,6-dimethylheptan-2-yl)oxalamide)
dineopentyl 2, 17-dimethyl-4,5, 14, 15-tetraoxo-3 ,6, 13, 16-tetraazaoctadecane- 1 , 1 8-dioate and nucleating agents with asymmetric flanking arms (R and R' are different), as e.g.:
2,5-dimethyl-4,7,8,15,16-pentaoxo-3-oxa-6,9,14,17-tetraazahenicosan-l-oic acid
The core motif comprises two oxalamide motifs. Amide motifs are hydrogen bonding motifs. They are the driving force for crystallization of the polymer. Because multiple amide motifs are present in the compound the hydrogen bonding is very strong. The hydrogen bonding leads to self-assembly of compound molecules, which form long needle-like structures that act as nucleating agent for the polymer.
In the present invention the amide motifs are connected by alkyl moieties (part of an alkane chain, -CH2-), which can differ in length between a methyl moiety (n=1 ) and a decanyl moiety (n=10). The different length of the alkyl moiety influences the peak melting and crystallization temperature of the compound in such a manner that a longer alkyl chain or spacer decreases the melting temperature while a shorter spacer increases the melting temperature (Table 1 ). Compare e.g. NA2 and NA5 in table 1 . The length of the aliphatic spacer can be used as a tool to design the optimal compound for a specific polymer matrix in terms of its solubility and melting temperature. Control of the melting point is useful to use the compound or a combination of compounds as efficient nucleating agent with polypropylene or different polypropylene copolymers which have a range of melting temperatures.
The nucleating agents according to present invention have peak melting temperatures ranging from 150 to 300°C. For example N1 ,N1 -(hexane-1 ,6- diyl)bis(N2-phenyloxalamide) has a peak melting temperature of 272°C.
Table 1 : Melting and crystallization temperature of nucleating agents
Tm - peak melting temperature of the nucleating agent
TC NA - peak crystallization temperature of the nucleating agent
The tunable melting temperature of the compounds is an advantage of the present invention over nucleating agents known previously. Also the high melting temperature of the compounds is an advantage over previously known nucleating agents. The high melting temperature that arises due to strong hydrogen bonding results in a very high nudeation efficiency of the nucleating agent. It also allows for the use of the compound or a combination of compounds as nudeation agent for polymers with a tailored melting temperature. For example, 100% iPP has an approximate peak melting temperature of 166°C, while a 93% propylene / 7% ethylene copolymer has a peak melting temperature of 140°C approximately.
The peak melting temperature (or dissolution temperature) of the nucleating agent decreases when mixed with the polymer. The decrease in the peak melting temperature (Tm) and peak crystallization temperature (Tc) of the nucleating agent when mixed with polypropylene shows its good miscibility in the polymer melt (Table 2).
Table 2: Crystallization of NA2 in a PP matrix.
The arms R and R' can be chosen in a way to improve the miscibility with the polymer. A good miscibility of the nucleating agent with the polymer causes a homogenous distribution of the nucleating agent in the polymer matrix and leads to better crystallization. This is obtained by designing the arms to be similar to the molecular configuration of the polymer. When R, R' and the molecular configuration of the polymer to be crystallized are similar, the crystal structure of the compound suppresses the nucleation barrier and increases the nucleation efficiency of the polymer, thus increasing the crystallization rate.
For the crystallization of polypropylene and polypropylene copolymers the flanking arms are independently of each other chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
In this way symmetric and asymmetric nucleating agents can be produced.
The nucleating agents according to present invention can be used to crystallize polypropylene polymer and polypropylene copolymers. For the purpose of this invention polypropylene includes isotactic, syndiotactic and atactic polypropylene, where the tacticity can vary from approximately 60 to 100% in the case of isotactic and syndiotactic polypropylenes.
Polypropylene copolymers for the purpose of this invention include polypropylene- alpha-olefin copolymers and poly(propylene-styrene) copolymers. Examples for suitable alpha-olefins include but are not limited to polyethylene (PE), polybutylene, and poly(4-methyl-1 -pentene). The polypropylene copolymers include polypropylene block copolymers and polypropylene random copolymers. The polypropylene copolymers comprise at least 60% propylene units. A preferred polypropylene copolymer is a propylene-ethylene copolymer, where e.g. the amount of ethylene monomers varies between 1 and 10 mole% based on the total amounts of monomers which are used to produce the polymer, preferably between 2 and 5 mole%.
In one embodiment according to this invention one compound according to the invention can be used to crystallize polypropylene and polypropylene copolymers. In another embodiment a combination of compounds according to present invention is used to crystallize polypropylene or polypropylene copolymers. For the crystallization the compound or the combination of compounds are applied at a
concentration of 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2-0.5wt% based on the weight of the polypropylene or propylene copolymer.
If a combination of compounds is used to crystallize polypropylene or polypropylene copolymers, said amounts refer to the combined amount of the different compounds. This means that the total amount of nucleating agent added to the polymer can either consists of one nucleating agent or a combination of different nucleating agents according to this invention. If a combination of nucleating agents is used, the total amount of nucleating agents is the same as if one nucleating agent is used. The amount is always based on the weight of the polymer or copolymer. For example, 0.05wt% of nucleating agent A and 0.05wt% of nucleating agent B result in an amount of 0.1 wt% nucleating agent based on the weight of the polymer.
The relative amount of each compound of such a combination of compounds can vary depending on the polymer, copolymer or polymer mixture which is to be crystallized.
In another embodiment the invention relates to a process for crystallization of polypropylene or polypropylene copolymer, comprising the steps of:
(a) mixing polypropylene or a polypropylene copolymer with a compound or a combination of compounds at a first temperature, ranging from 10°C to 140°C above the peak melting temperature of the polymer; and
(b) cooling the polymer at a second temperature, ranging from the first
temperature to 20°C, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
When studying the morphology of the nucleating agents according to this invention in the polymer matrix with optical microscopy, a fine needle-like morphology of the nucleating agents can be observed and the polymer starts crystallizing from the surface of the nucleating agent. The presence of the fine needle-like morphology of the nucleating agent enhances the nucleation efficiency of the polymer in comparison with a polymer without nucleating agents. The dimensions of the needle-like crystals vary with the crystallization conditions and the chosen combinations of the nucleating agents. With smaller crystal size the surface area of the nucleation site is increased which improves the crystallization and nucleation efficiency.
In one embodiment the nucleating agents of present invention have a crystal size in the polymer matrix of up to 50 micrometer (μιτι). Preferably the crystal size is below several hundreds of nanometer (nm), e.g. between 10 and 750 nm, more preferably between 50 and 500 nm, even more preferably between 100 and 250 nm. The crystal size of the nucleating agent in the polymer matrix can be determined by optical microscopy or electron microscopy or atomic force microscopy.
The nucleating agents according to the invention show high nucleation efficiencies. The nucleation efficiency (NE) is defined as the increase of the
crystallization temperature of the polymer with the nucleating agent compared to the crystallization temperature without nucleating agent. This is calculated by using equation 1 :
NE = (Tc - Tcl )/(rc2max - Tel ) x 100% , where Tci and TC2max are the peak crystallization temperatures of the non- nucleated and self-nucleated polymer, respectively. Tc is the peak crystallization temperature of the polymer with the nucleating agents.
Polypropylene and polypropylene copolymers crystallize inefficiently without a nucleating agent in industrial processing. The material which can be obtained without nucleating agent is of lower crystallinity and has a lower dimensional stability.
However, with the here described nucleating agents or combinations thereof the onset temperature for crystallization of the polymer is increased. The here described nucleating agents or combinations thereof increase the onset crystallization temperature by at least 5°C, preferably by at least 10°C, more preferably by at least 15°C, or by at least 20°C compared to the polymer or copolymer without any nucleating agent. The specific temperature depends on the specific compound or combination of compounds according to this invention, the amount of nucleating agent and the polymer or copolymer. A higher onset temperature is better for the produced plastics because the mechanical properties of the material are better, the production time is shorter because less cooling has to take place and no or less shrinkage of the crystallized polymer occurs. The high nucleation efficiency provides the desired dimension stability. Thus, the high onset crystallization temperature of the polymer or copolymer in the presence of the nucleating agents of present invention enables easier processibilty and a higher dimension stability of the polymer product. Additionally, PP or PP copolymers crystallized with nucleating agents according to this invention or a combination of those have a good transparency.
With the nucleating agents according to this invention the temperature at which the polymer and the compound or combination of compounds are mixed ranges between 10°C and 140°C, preferably between 20 and 120°C, more preferably between 40°C and 120°C above the peak melting temperature of the polymer.
The temperature at which the polymer and the compound or combination of compounds are cooled ranges from about 140°C above the peak melting temperature of the polymer to 20°C, preferably from 120°C above the peak melting temperature of the polymer to 20°C. In one embodiment the polymer and the compound or combination of compounds are cooled at room temperature.
As pointed out before a high crystallization temperature is beneficial for the polymer product and its production.
The cooling occurs at a rate ranging between 1 °C/min and 500°C/min, preferably between 10°C/min and 300°C/min, more preferably between 20°C/min and 100°C /min.
With an increasing cooling rate the nucleation efficiency becomes more evident and it reduces production time.
In another embodiment the invention relates to a composition comprising polypropylene or polypropylene copolymer, and a compound or a combination of compounds, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
The composition comprises 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2- 0.5wt% of the compound or a combination of compounds based on the weight of the polypropylene or propylene copolymer.
In one embodiment films, moldings, composite materials, injection- or extrusion- molded products or elongated products comprise a composition according to this invention. Elongated products include fibers, as e.g. staple fiber and short fiber.
It is also possible to crystallize a polymer mixture of polypropylene homopolymer and polypropylene copolymer with a compound or combination of compounds according to this invention. The resulting composition can therefore comprise polypropylene, polypropylene copolymer or a polymer mixture together with one compound or a combination of compounds according to this invention.
Such compositions can be used to produce films, moldings, composite materials, injection- or extrusion molded products or elongated products.
More specifically, any of said compositions can be used in plastic carrier bags, bottles, food packaging products and textiles. Especially advantageous is the use of a composition according to the invention for bottles and food packaging products because many of the nucleating agents according to present invention are considered non-toxic.
The following examples describe the invention in more detail but by no means limit the scope of the invention.
Synthesis of compound & methods for measuring the characteristics of compound and compound-polymer composition
1 . Synthesis of compounds
As an example the synthesis of NA1 and NA2 is described:
a) Synthesis of NA1 (N1,N1 -(hexane-1 ,6-diyl)bis(N2-phenyloxalamide))
Ethyl oxanilate (5 g, 25.8 mmol) was dissolved in 200 ml of chloroform. 1 ,6- hexamethylenediamine (1 .5 g, 12.9 mmol) was added and the mixture was left to stir under reflux for 48 hours. The formed precipitate was filtered and washed successively with chloroform and diethyl ether before drying in vacuo overnight (80 °C). The product was obtained as a white powder, showed a (1 st) melting point of 273°C and a crystallization point at 252°C. The compound is thermally stable up to 280 °C. Nuclear magnetic resonance spectroscopy (1H-NMR) analysis of NA1 gave the following result: (Yield 4,78 g, 90%). 1 H-NMR(TFA-d) δ (ppm): 7.46 (d, ArH, 4H), 7.35 (t, ArH, 4H), 7.25 (t, ArH, 2H), 3.45 (t, NH-CH2, 4H), 1 .70 (m, NH- CH2-CH2, 4H ), 1 .45 (m, NH-CH2-CH2-CH2, 4H). b) Synthesis of NA2 (N1,N1 '-(ethane-1 ,2-diyl)bis(N2-hexyloxalamide))
Diethyl 2,2'-(ethane-1 ,2-diylbis(azanediyl))bis(2-oxoacetate) (5 g, 19.2 mmol) and hexylamine (3.91 g, 38.4 mmol) were dissolved in 200 ml chloroform. The mixture was refluxed for 48 hours and the precipitate was filtered and washed with chloroform and diethyl ether before drying in vacuo at 80 °C overnight (yield 6.55 g, 92%). The obtained powder shows a melting point of 287°C and re-crystallizes at 278°C. The product starts to degrade around 280°C with its onset point at 300°C. 1H-NMR spectroscopy of NA2 gave the following result: 1 H-NMR(TFA-d) δ (ppm): 3.66 (s, NH-CH2-CH2-NH, 4H), 3.35 (t, NH-CH2-CH2-CH2, 4H), 1 .59 (m, NH-CH2-CH2-CH2, 4H), 1 .28 (b, CH2, 12H), 0.83 (t, CH3, 6H).
2. Melt mixing
Melt mixing of the nucleating agent and the polymer was performed using a mini- extruder with sample residence time of 5 min after complete feeding. In the examples isotactic polypropylene (Sabic, grade 1531 P) or a propylene-ethylene copolymer comprising 5 mole% (Dow, Versify 2000®) or 9 mole% (Dow, Versify 2200®) of ethylene monomers and 95 mole% or 91 mole% of propylene monomers respectively was used as polymer. All samples were prepared using 0- 1 % of a nucleating agent by weight of the polymer. The samples were processed at 230 or 280°C.
3. Differential Scanning Calorimetry (DSC)
Melting and crystallization of polymers without and with nucleating agent was investigated using DSC (TA Q1000 instrument) under nitrogen atmosphere. The heating rate was always 20°C/min and cooling rates of all samples were 100°C/min and/or 10°C/min (as indicated) with 3 min of isothermal condition at limiting temperatures. The samples were heated up to 230°C or 280°C (as indicated) and cooled down to 20°C. Isothermal crystallization measurements were performed on the polymer without and with nucleating agent at 130°C for an isothermal time of 1 hr.
The onset melting temperature is defined as the start of the endothermic process, whereas the peak melting temperature or peak melting point is defined as the peak of the endothermic process recorded by DSC. The onset crystallization temperature is defined as the start of the exothermic process, whereas the peak crystallization temperature is defined as the peak of the exothermic process recorded by DSC.
4. Optical Microscopy
Crystallization measurements were conducted on a Zeiss Axioplan 2 Imaging optical microscopy under crossed polarizers with a CD achorplan objective (Zoom). A THMS 600 heating stage connected to a Linkam TMS 94 control unit was mounted on the optical microscope. Samples were heated to above the
melting temperature of the polymer and cooled at a specific cooling rate under nitrogen atmosphere.
Abbreviations and symbols:
NA1 : N1 ,N1 -(hexane-1 ,6-diyl)bis(N2-phenyloxalamide)
NA2 : N1 ,N1 '-(ethane-1 ,2-diyl)bis(N2-hexyloxalamide)
NA3 : N1 ,N1 '-(ethane-1 ,2-diyl)bis(N2-decyloxalamide)
NA4 : N1 ,N1'-(ethane-1 ,2-diyl)bis(N2-hexadecyloxalamide)
NA5 : N1 ,N1'-(hexane-1 ,6-diyl)bis(N2-hexyloxalamide)
NE : Nucleation efficiency (according to equation 1 )
Tm : Peak melting temperature of the polymer, nucleating agent or polymer in the presence of the nucleating agent (cf. tables 3 and 4)
TC /TC N : Peak crystallization temperature of the polymer in the presence of the nucleating agent (TC N) or of the pristine polymer (Tc)
Tonset : Onset of crystallization temperature of the polymer in the presence of the nucleating agent or of the pristine polymer
Xc Percentage crystallinity of the polymer
to.5 Half time of isothermal crystallization of the polymer
AHm Enthalpy of melting of the polymer
Enthalpy of crystallization of the polymer
Tel peak crystallization temperature of the non-nucleated polymer
Tc2max peak crystallization temperature of the self-nucleated polymer
Example 1
Polypropylene and a varying amount of the nucleating agents NA1 , NA2, NA3, NA4, NA5 or sorbitol (DMDBS) were melt-mixed and processed at 230 or 280°C. The cooling rate was set to 10 or 100°C/min. A cooling rate of 100°C/min corresponds to conditions similar to those used in industrial production. The nucleating efficiencies of the nucleating agents are shown in Table 3. The polymer without the nucleating agent crystallizes at 1 13 and 105°C corresponding to the cooling rate of 10 and 100 °C/min, respectively, whereas the polymer in the
presence of nucleating agents can crystallize at a range of temperatures (Table 3). The nucleating agent NA2 at a concentration of 0.4 and 1 .0wt% showed a very good nudeation efficiency for the polymer matrix at faster (100°C/min) and as well at slower (10°C/min) cooling rates.
Table 3: Nudeation efficiency of NA for PP obtained from DSC measurements.
Sample Tc Tonset Xc Tm NE* Processing Cooling
(°C) (°C) (%) (°C) (%) temperature rate
(°C) (°C/min)
NA1 251 272 10
NA2 282 289 10
NA3 258 264 10
NA4 244 248 10
NA5 221 225 10
PP 1 13 1 16 43 166 0 230 10
PP + 1 .0 wt% NA1 1 17 128 42 164 16 230 10
PP + 0.4 wt% NA2 120 124 43 163 29 230 10
PP + 1 .0 wt% NA2 123 127 44 164 41 230 10
PP + 1 .0 wt% NA3 120 123 44 163 27 230 10
PP + 0.5 wt% NA4 1 16 1 18 45 162 12 230 10
PP + 1 .0 wt% NA4 1 15 1 17 44 161 8 230 10
PP + 0.5 wt% NA5 1 19 124 44 165 25 230 10
PP + 1 .0 wt% NA5 121 125 43 162 33 230 10
PP 105 109 43 166 0 230 100
PP + 1 .0 wt% NA1 1 16 121 44 164 40 230 100
PP + 0.4 wt% NA2 1 12 1 17 44 159 26 230 100
PP + 1 .0 wt% NA2 1 15 1 19 45 164 37 230 100
PP + 1 .0 wt% NA3 1 12 1 15 45 163 26 230 100
PP + 0.5 wt% NA4 1 16 1 18 43 162 40 230 100
PP + 1 .0 wt% NA4 1 1 1 1 13 44 161 22 230 100
PP + 0.5 wt% NA5 1 1 1 1 16 44 160 22 230 100
PP + 1 .0 wt% NA5 1 12 1 17 44 160 26 230 100
PP + 0.2 wt% NA2 1 13 1 17 44 159 29 280 100
PP + 0.2 wt%
DMDBS 1 13 1 15 44 159 29 280 100
PP 1 12 1 15 43 159 0 280 10
PP + 0.2 wt% NA2 1 19 123 46 159 25 280 10
PP + 0.5 wt% NA2 122 126 43 161 49 280 10
PP + 1 .0 wt% NA2 122 126 48 159 49 280 10
PP + 0.2 wt%
DMDBS 1 17 1 18 44 159 16 280 10
*: according to the above definition, i.e. equation 1 . TC2max is 137.4°C (referred from Journal of Thermal Analysis, 1994, 42, 721 -731 ) and 132.3°C (measured by DSC at a cooling rate of 100 °C/min from a partial melt state) for the cooling rate of 10°C/min and 100°C/min, respectively.
To investigate how the nucleating agents influence crystallization time, the half time of crystallization was measured by DSC.
In the presence of the nucleating agent, the isothermal crystallization results, as shown in Table 4, clearly demonstrate that the half time of crystallization (t0 5) decreased dramatically after using nucleating agents, at the same time an increase in the melt enthalpy of the polymer is evident.
Table 4: Isothermal crystallization results of PP with varying nucleating agents obtained from DSC measurements.
Example 2
For a comparison, the same process as for example 1 was carried out with different nucleating agents known from the prior art to compare the nucleating agents of present invention and those already known. N'1, N'9 diheptanoylnonane- dihydrazide (DHNHZ) and N1,N6-diphenyladipamide (DPAD) were tested. DPAD is a bisamide compound with an aliphatic linker between the amide groups and benzol rings as side arms. DHNHZ is a dihydrazide, i.e. the order of the amide groups is inverted when compared to an oxalamide residue. The results of the known nucleating agents and nucleating agents according to this invention are listed in Table 5.
Table 5: Crystallization of P with various nucleating agents.
Sample Tc Tonset Xc Tm NE* Processing Cooling
(°C) (°C) (%) (°C) (%) temperature rate
(°C) (°C/min)
PP 105 1 14 44 161 0 230 100
PP + 0.5wt% 151/
DPAD 1 1 1 1 18 37 162** 22 230 100
PP + 0.5wt%
DHNHZ 108 1 16 45 160 1 1 230 100
PP + 0.4 wt% NA2 1 12 1 17 44 159 26 230 100
PP + 1 .0 wt% NA2 1 15 1 19 45 164 37 230 100
PP + 0.5 wt% NA4 1 16 1 18 43 162 40 230 100
*: according to the above definition, i.e. equation 1 . TC2max is 137.4°C (referred from Journal of Thermal Analysis, 1994, 42, 721 -731 ) and 132.3°C (measured by DSC at a cooling rate of 100 °C/min from a partial melt state) for the cooling rate of 100°C/min, respectively.
**: double melting peaks observed
The results show that the nucleating agents of the prior art result in a lower nucleating efficiency and also lower crystallinity compared to the nucleation agents of present invention.
The bisamide compound known from EP0557721 and EP1431335 (as e.g. DPAD) and the compounds described in EP0421377 comprise amide motifs and cyclic or aromatic groups. In contrast, the nucleating agents of present invention do not comprise cyclic or aromatic groups.
Without to be bound by any theory one can speculate that the aromatic or cyclic groups of the nucleating agents of the prior art are likely to perturb the aggregation of the amide motifs due to the sterical hindrance of the cyclic or aromatic motifs. This could result in a lower nucleation efficiency when used as nucleating agents for polypropylene or polypropylene copolymers. EP0421377 describes the use of such nucleating agents to crystallize polyethylene terephthalates.
Example 3
The nucleating agents of present invention are also suited for the crystallization of polypropylene copolymers. A propylene-ethylene copolymer (PP-co-PE) comprising 5 mole% (Dow, Versify 2000®) or 9 mole% (Dow, Versify 2200®) of ethylene monomers and 95 mole% or 91 mole% of propylene monomers respectively was used as polymer for the crystallization with NA2.
No nucleating efficiency can be determined because the maximum crystallinity for the specific mole% of the copolymer will be dependent on the polymerization conditions like catalyst, temperature etc. However, the increase of the Tc and TonSet in presence of the nucleating agent indicate that the nucleating agent according to this invention enhances the crystallization temperature of copolymers and promotes crystallization.
Table 6: Crystallization of polypropylene copolymers
Sample Processing Cooling
Tc Tonset temperature rate
(°C) (°C) (°C) (°C/min)
PP-co-PE (5%) 74 78 230 10
PP-co-PE (5%) + 0.5
wt% NA2 79 83 230 10
PP-co-PE (5%) 67 71 230 100
PP-co-PE (5%) + 0.5
wt% NA2 70 75 230 100
Claims
Nucleating agents for polypropylene and polypropylene copolymers
Claims:
1 ) Use of a compound or a combination of compounds for crystallization of polypropylene or polypropylene copolymers, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or analkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
2) The use of the compound or the combination of compounds according to claim 1 wherein at least one of the side arms R and R' is chosen from an alkyl group with a total carbon number between 2 and 20, preferably with a total carbon number between 4 and 10 and more preferably with a total carbon number between 6 and 8.
3) The use of the compound or the combination of compounds according to claim 1 or 2 wherein each of the compounds has a peak melting temperature ranging between 150 and 300°C.
4) The use of the compound or the combination of compounds according to any one of claims 1 -3 wherein the compound or the combination of compounds are applied at a concentration of 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2- 0.5wt% based on the weight of the polypropylene or propylene copolymer.
5) A process for crystallization of polypropylene or polypropylene copolymers, comprising the steps of:
(a) mixing polypropylene or a polypropylene copolymer with a compound or a combination of compounds at a first temperature, ranging from 10°C to 140°C above the peak melting temperature of the polymer; and
(b) cooling the polymer at a second temperature, ranging from the first
temperature to 20°C, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
6) The process according to claim 5, wherein each of the compounds has a peak melting temperature ranging between 150°C and 300°C.
7) The process according to claim 5 or 6, wherein the compound or the combination of compounds are applied at a concentration of 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2-0.5wt% based on the weight of the polypropylene or propylene copolymer.
8) The process according to any one of claims 5 to 7, wherein the first temperature ranges between 10°C and 140°C, preferably between 20°C and 120°C, more preferably between 40°C and 120°C above the peak melting temperature of the polymer.
9) The process according to any one of claims 5 to 8, wherein the second temperature ranges from 140°C above the peak melting temperature of the polymer to 20°C, preferably from 120°C above the peak melting temperature of the polymer to 20°C.
10) The process according to any one of claims 5 to 9, wherein the cooling occurs at a rate ranging between 1 °C /min and 500°C /min, preferably between 10°C /min and 300°C /min, more preferably between 20°C /min and 100°C /min.
1 1 ) A composition comprising polypropylene or polypropylene copolymer, and a compound or a combination of compounds, characterized in that each of said compounds comprises a core motif with two oxalamide motifs, flanked by two arms, wherein said core motif has the formula:
R-NH-C(O)-C(O)-NH-(CH2)n-NH-C(O)-C(O)-NH-R', wherein n is between 1 and 10 and the arms R and R' are each independently of one another chosen from:
(i) H;
(ii) an alkyl group with a total number of carbon atoms between 1 and 20; or
(iii) one of the following esters:
- X-Ester-Y,
- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-Y,
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-Y, or
- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester- X-Ester-X-Ester-X-Ester-Y;
wherein X is a saturated aliphatic hydrocarbon group comprising 1 to 20 carbon atoms, Y is chosen from H or an alkyl group with a total number of carbon atoms between 1 and 20 and Ester is -C(O)-O- or -O-C(O)-.
12) The composition according to claim 1 1 , wherein the compound or a combination of compounds is applied at a concentration of 0.05-2wt%, preferably 0.1 -1wt%, more preferably 0.2-0.5wt% based on the weight of the polymer.
13) A film, molding, composite material, extrusion- or injection-molded product or elongated product comprising the composition according to claim 1 1 or 12.
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|---|---|---|---|
| EP13717273.0A EP2838948A1 (en) | 2012-04-19 | 2013-04-18 | Nucleating agents for polypropylene and propylene copolymers |
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| EP13717273.0A EP2838948A1 (en) | 2012-04-19 | 2013-04-18 | Nucleating agents for polypropylene and propylene copolymers |
| PCT/EP2013/058082 WO2013156565A1 (en) | 2012-04-19 | 2013-04-18 | Nucleating agents for polypropylene and propylene copolymers |
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| CN104164060B (en) * | 2014-07-22 | 2016-04-06 | 江南大学 | One can biological compost polyester material composition and method of making the same |
| CN113621175B (en) * | 2021-08-13 | 2022-10-18 | 中国科学院化学研究所 | A kind of high-efficiency isotactic polypropylene β crystal nucleating agent and its preparation method and application |
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| US6235823B1 (en) | 1992-01-24 | 2001-05-22 | New Japan Chemical Co., Ltd. | Crystalline polypropylene resin composition and amide compounds |
| US20040249031A1 (en) | 2001-09-12 | 2004-12-09 | Kiyoshi Sadamitsu | Polypropylene resin moldings and process for production thereof |
| EP1939167A1 (en) | 2006-12-19 | 2008-07-02 | Borealis Technology OY | Beta-nucleating agent for polyproplyene and process for its preparation |
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