WO2024038431A1 - Flame-retarded polyamide compositions with good electrical performance - Google Patents
Flame-retarded polyamide compositions with good electrical performance Download PDFInfo
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- WO2024038431A1 WO2024038431A1 PCT/IL2023/050825 IL2023050825W WO2024038431A1 WO 2024038431 A1 WO2024038431 A1 WO 2024038431A1 IL 2023050825 W IL2023050825 W IL 2023050825W WO 2024038431 A1 WO2024038431 A1 WO 2024038431A1
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- Prior art keywords
- polyamide
- weight
- bromine
- composition according
- cti
- Prior art date
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- 239000004952 Polyamide Substances 0.000 title claims abstract description 100
- 229920002647 polyamide Polymers 0.000 title claims abstract description 100
- 239000000203 mixture Substances 0.000 title claims abstract description 75
- 229910000149 boron phosphate Inorganic materials 0.000 claims abstract description 33
- YZYDPPZYDIRSJT-UHFFFAOYSA-K boron phosphate Chemical compound [B+3].[O-]P([O-])([O-])=O YZYDPPZYDIRSJT-UHFFFAOYSA-K 0.000 claims abstract description 30
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical class N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 16
- 230000000052 comparative effect Effects 0.000 claims abstract description 8
- 230000002708 enhancing effect Effects 0.000 claims abstract description 4
- 229910052794 bromium Inorganic materials 0.000 claims description 33
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 31
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 claims description 30
- 229920002292 Nylon 6 Polymers 0.000 claims description 26
- 229920000642 polymer Polymers 0.000 claims description 25
- 239000003365 glass fiber Substances 0.000 claims description 13
- 238000012360 testing method Methods 0.000 claims description 13
- 239000004793 Polystyrene Substances 0.000 claims description 12
- 229920002223 polystyrene Polymers 0.000 claims description 12
- 239000000654 additive Substances 0.000 claims description 10
- 239000011521 glass Substances 0.000 claims description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 7
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 6
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 6
- 230000000996 additive effect Effects 0.000 claims description 5
- 239000000454 talc Substances 0.000 claims description 5
- 229910052623 talc Inorganic materials 0.000 claims description 5
- 229920001169 thermoplastic Polymers 0.000 claims description 5
- 239000004416 thermosoftening plastic Substances 0.000 claims description 5
- GRKDVZMVHOLESV-UHFFFAOYSA-N (2,3,4,5,6-pentabromophenyl)methyl prop-2-enoate Chemical compound BrC1=C(Br)C(Br)=C(COC(=O)C=C)C(Br)=C1Br GRKDVZMVHOLESV-UHFFFAOYSA-N 0.000 claims description 4
- 239000003822 epoxy resin Substances 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 229920000647 polyepoxide Polymers 0.000 claims description 3
- 125000001246 bromo group Chemical group Br* 0.000 claims description 2
- 238000009472 formulation Methods 0.000 description 14
- 239000003063 flame retardant Substances 0.000 description 13
- ADCOVFLJGNWWNZ-UHFFFAOYSA-N antimony trioxide Inorganic materials O=[Sb]O[Sb]=O ADCOVFLJGNWWNZ-UHFFFAOYSA-N 0.000 description 9
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 description 8
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 6
- GHPGOEFPKIHBNM-UHFFFAOYSA-N antimony(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Sb+3].[Sb+3] GHPGOEFPKIHBNM-UHFFFAOYSA-N 0.000 description 6
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 description 6
- 239000000178 monomer Substances 0.000 description 6
- 238000006116 polymerization reaction Methods 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- -1 aromatic dicarboxylic acids Chemical class 0.000 description 4
- 150000004985 diamines Chemical class 0.000 description 4
- 239000000945 filler Substances 0.000 description 4
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000008188 pellet Substances 0.000 description 4
- KIDHWZJUCRJVML-UHFFFAOYSA-N putrescine Chemical compound NCCCCN KIDHWZJUCRJVML-UHFFFAOYSA-N 0.000 description 4
- YEAUATLBSVJFOY-UHFFFAOYSA-N tetraantimony hexaoxide Chemical compound O1[Sb](O2)O[Sb]3O[Sb]1O[Sb]2O3 YEAUATLBSVJFOY-UHFFFAOYSA-N 0.000 description 4
- 239000004953 Aliphatic polyamide Substances 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000001361 adipic acid Substances 0.000 description 3
- 235000011037 adipic acid Nutrition 0.000 description 3
- 125000001931 aliphatic group Chemical group 0.000 description 3
- 229920003231 aliphatic polyamide Polymers 0.000 description 3
- 238000001125 extrusion Methods 0.000 description 3
- 238000001746 injection moulding Methods 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 150000003951 lactams Chemical class 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 238000006068 polycondensation reaction Methods 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- KXDHJXZQYSOELW-UHFFFAOYSA-N Carbamic acid Chemical compound NC(O)=O KXDHJXZQYSOELW-UHFFFAOYSA-N 0.000 description 2
- 229920002302 Nylon 6,6 Polymers 0.000 description 2
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical class C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- BDJRBEYXGGNYIS-UHFFFAOYSA-N nonanedioic acid Chemical compound OC(=O)CCCCCCCC(O)=O BDJRBEYXGGNYIS-UHFFFAOYSA-N 0.000 description 2
- 235000011007 phosphoric acid Nutrition 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000012763 reinforcing filler Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 238000007151 ring opening polymerisation reaction Methods 0.000 description 2
- CXMXRPHRNRROMY-UHFFFAOYSA-N sebacic acid Chemical compound OC(=O)CCCCCCCCC(O)=O CXMXRPHRNRROMY-UHFFFAOYSA-N 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- GUOSQNAUYHMCRU-UHFFFAOYSA-N 11-Aminoundecanoic acid Chemical compound NCCCCCCCCCCC(O)=O GUOSQNAUYHMCRU-UHFFFAOYSA-N 0.000 description 1
- JCUZDQXWVYNXHD-UHFFFAOYSA-N 2,2,4-trimethylhexane-1,6-diamine Chemical compound NCCC(C)CC(C)(C)CN JCUZDQXWVYNXHD-UHFFFAOYSA-N 0.000 description 1
- DPQHRXRAZHNGRU-UHFFFAOYSA-N 2,4,4-trimethylhexane-1,6-diamine Chemical compound NCC(C)CC(C)(C)CCN DPQHRXRAZHNGRU-UHFFFAOYSA-N 0.000 description 1
- RLEQVGMLDNITBW-UHFFFAOYSA-N 2,4,4-trimethylhexanedioic acid Chemical compound OC(=O)C(C)CC(C)(C)CC(O)=O RLEQVGMLDNITBW-UHFFFAOYSA-N 0.000 description 1
- VEORPZCZECFIRK-UHFFFAOYSA-N 3,3',5,5'-tetrabromobisphenol A Chemical compound C=1C(Br)=C(O)C(Br)=CC=1C(C)(C)C1=CC(Br)=C(O)C(Br)=C1 VEORPZCZECFIRK-UHFFFAOYSA-N 0.000 description 1
- WTKWFNIIIXNTDO-UHFFFAOYSA-N 3-isocyanato-5-methyl-2-(trifluoromethyl)furan Chemical compound CC1=CC(N=C=O)=C(C(F)(F)F)O1 WTKWFNIIIXNTDO-UHFFFAOYSA-N 0.000 description 1
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004609 Impact Modifier Substances 0.000 description 1
- JHWNWJKBPDFINM-UHFFFAOYSA-N Laurolactam Chemical compound O=C1CCCCCCCCCCCN1 JHWNWJKBPDFINM-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 239000006057 Non-nutritive feed additive Substances 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 229920000388 Polyphosphate Polymers 0.000 description 1
- 239000004954 Polyphthalamide Substances 0.000 description 1
- 229920006121 Polyxylylene adipamide Polymers 0.000 description 1
- 239000005700 Putrescine Substances 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 239000012963 UV stabilizer Substances 0.000 description 1
- GKXVJHDEWHKBFH-UHFFFAOYSA-N [2-(aminomethyl)phenyl]methanamine Chemical compound NCC1=CC=CC=C1CN GKXVJHDEWHKBFH-UHFFFAOYSA-N 0.000 description 1
- VZDWAGGFTOPBRS-UHFFFAOYSA-B [O-]P([O-])(=O)OP(=O)([O-])[O-].[B+3].[O-]P([O-])(=O)OP(=O)([O-])[O-].[O-]P([O-])(=O)OP(=O)([O-])[O-].[B+3].[B+3].[B+3] Chemical compound [O-]P([O-])(=O)OP(=O)([O-])[O-].[B+3].[O-]P([O-])(=O)OP(=O)([O-])[O-].[O-]P([O-])(=O)OP(=O)([O-])[O-].[B+3].[B+3].[B+3] VZDWAGGFTOPBRS-UHFFFAOYSA-B 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 150000004984 aromatic diamines Chemical class 0.000 description 1
- YDLSUFFXJYEVHW-UHFFFAOYSA-N azonan-2-one Chemical compound O=C1CCCCCCCN1 YDLSUFFXJYEVHW-UHFFFAOYSA-N 0.000 description 1
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 229920006018 co-polyamide Polymers 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- QFTYSVGGYOXFRQ-UHFFFAOYSA-N dodecane-1,12-diamine Chemical compound NCCCCCCCCCCCCN QFTYSVGGYOXFRQ-UHFFFAOYSA-N 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 238000007706 flame test Methods 0.000 description 1
- 125000003055 glycidyl group Chemical group C(C1CO1)* 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000012764 mineral filler Substances 0.000 description 1
- TVIDDXQYHWJXFK-UHFFFAOYSA-N n-Dodecanedioic acid Natural products OC(=O)CCCCCCCCCCC(O)=O TVIDDXQYHWJXFK-UHFFFAOYSA-N 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 239000001205 polyphosphate Substances 0.000 description 1
- 235000011176 polyphosphates Nutrition 0.000 description 1
- 229920006375 polyphtalamide Polymers 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 229920006012 semi-aromatic polyamide Polymers 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000010189 synthetic method Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000004154 testing of material Methods 0.000 description 1
- HQHCYKULIHKCEB-UHFFFAOYSA-N tetradecanedioic acid Natural products OC(=O)CCCCCCCCCCCCC(O)=O HQHCYKULIHKCEB-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
- C08L77/06—Polyamides derived from polyamines and polycarboxylic 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
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/38—Boron-containing compounds
-
- 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
- C08K7/00—Use of ingredients characterised by shape
- C08K7/02—Fibres or whiskers
- C08K7/04—Fibres or whiskers inorganic
- C08K7/14—Glass
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
- C08L25/18—Homopolymers or copolymers of aromatic monomers containing elements other than carbon and hydrogen
Definitions
- PA polyamide
- GF glass fibers
- Flammability characteristics of plastics are often quantified by a method specified by Underwriter Laboratories standard UL 94, where an open flame is applied to the lowermost edge of a vertically mounted test specimen made of the tested polymer formulation.
- the specimens used in the UL 94 test method vary in thickness (typical thicknesses are ⁇ 3.2 mm, ⁇ 1.6 mm, ⁇ 0.8 mm and ⁇ 0.4mm) .
- various features of the flammability of the test specimens are recorded.
- the polymer formulation is assigned with either V-0, V-l or V-2 rating at the measured thickness of the test specimen.
- Polymer formulation assigned with the V-0 rating is the least flammable. In the UL-94 burning test, the thinner the specimens are, the longer the burning time.
- Such polyamide formulations that are described for example by Weil and Levchik in "Current Practice and Recent Commercial Developments in Flame Retardancy of Polyamides” (Journal of Fire Science, Vol. 22, 2004, p.251-263) show that flame retardation of polyamides with the brominated flame retardant /Sb2O3 system is quite efficient, with filled polyamides (e.g., PA 6, 6/GFso) achieving UL-94 V- 0/0.8 mm rating at a reasonable loading of the flame retardant system.
- filled polyamides e.g., PA 6, 6/GFso
- CTI Comparative Tracking Index
- the invention is primarily directed to a polyamide composition
- a polyamide composition comprising a polyamide, a brominated flame retardant and boron phosphate (or boron pyrophosphate, or boron polyphosphate) .
- the invention also relates to a method of reducing the flammability and enhancing the comparative tracking index of a polyamide to achieve UL 94 V-0 rating and reach 500 ⁇ CTI ⁇ 600 V, e.g., 550 ⁇ CTI ⁇ 600 V, which method comprises adding a brominated flame retardant and boron phosphate to the polyamide .
- polyamides for use in the invention are of course commercially available and can be prepared by well-known methods, e.g., polycondensation reactions of dibasic carboxylic acids and diamines (or amino-carboxylic acid) and ring-opening polymerization of lactams, that are described, for example, in Nylon Plastics Handbook M., ed. I. Kohan, 1995, Kunststoff, Hanser.
- the monomers used in the preparation of polyamides by polycondensation reactions are aliphatic and/or aromatic dicarboxylic acids and aliphatic and/or aromatic diamines, hence the polyamides may be wholly aliphatic/cycloaliphatic, wholly aromatic or mixed aliphatic-aromatic.
- Major dicarboxylic acid monomers include adipic acid, 2,2,4 and 2 , 4 , 4-trimethyl adipic acid, azelaic acid, sebacic acid, 1 , 1 O-decanedicarboxylic acid, 1 , 12-dodecanedioic acid, isophthalic acid and terephthalic acid.
- Major diamine monomers include hexamethylenediamine, tetramethylenediamine, 2,2,4- trimethyl hexamethylenediamine, 2 , 4 , 4-trimethyl hexamethylenediamine, 1 , 4-diaminobutane, 1,12- dodecanediamine and xylylenediamine .
- aminocarboxylic acids 11-amino undecanoic acid could be mentioned.
- aliphatic polyamides obtained by polycondensation reactions of dibasic acid HO2C (CH2) xCChH and diamine NH2(CH2) y NH2 can be used in the invention.
- lactams such as the polymerization of caprolactam to give PA 6 (polycaprolactam) , which takes place in water with cationic or anionic initiator.
- lactam monomers besides caprolactam include capryllactam and lauryllactam.
- polyamides that can be used in the invention, obtainable by the synthetic methods set out above, are aliphatic polyamides such as PA 6, 6, PA 6, PA 6,9, PA 6,10, PA 6,12, PA 11, PA 12, PA 12,12, PA 4, 6 and partially aromatic polyamides such as polyxylylene adipamide and polyphthalamides formed by the reaction of ferephthalic acid/ Isophthalic acid with aliphatic diamines, such as hexamethylene diamine.
- aliphatic polyamides such as PA 6, 6, PA 6, PA 6, PA 6,9, PA 6,10, PA 6,12, PA 11, PA 12, PA 12,12, PA 4, 6 and partially aromatic polyamides such as polyxylylene adipamide and polyphthalamides formed by the reaction of ferephthalic acid/ Isophthalic acid with aliphatic diamines, such as hexamethylene diamine.
- the concentration of the polyamide in the composition of the invention is from 30 to 80 % by weight, e.g., in filled grades it may vary in the range from 30 to 60% and in unfilled grades it is usually from 60 to 80% (based on the total weight of the composition) .
- polyamides includes copolyamides, such as those described in length in US 2020/0115551, e.g., the polymerization product of diamine (for example, hexamethylenediamine) , dibasic acid (for example, adipic acid) and a monomer capable of self-condensation (for example, caprolactam) to form a co-polyamide such as PA 6, 6/6.
- Polyamide blends obtained for example by melt-mixing in an extruder two types of polyamides, such as PA 6, 6 and PA 6, to give PA 6, 6 + PA 6 blend (PA 6, 6 is usually the predominant component) can also benefit from the invention.
- the brominated flame retardant added to the polyamide is preferably a bromine-containing polymer.
- Brominated polystyrene is prepared by methods known in the art (see US 4,879,353 and US 5,532,322) .
- Suitable grades have weight average molecular weight in the range of about 500, 000-600,000, with bromine content preferably exceeding 60 or even 65 % by weight e.g., 66% (that is, average of 2-3 bromine atoms per aromatic ring in the polymer backbone chain) .
- Such brominated polymers in the form of a free-flowing powder or in granular form, are available on the market, e.g., from ICL-IP (FR 803P) .
- Poly (pentabromobenzyl acrylate) represented by the following formula:
- the polymer (abbreviated PBBPA) is produced by polymerizing the corresponding monomer pentabromobenzyl acrylate, either in bulk (in an extruder at a temperature in the range from 120°C to 290°C as described in US 4,996,276) , or in solution, see US 4,128,709 or 6,028,156.
- the polymer is also available on the marketplace, being sold by ICL-IP (FR-1025) .
- ICL-IP FR-1025
- brominated epoxy resins and end-capped derivatives thereof represented by the Formula (I) :
- Ri and R2 are independently selected from the group consisting of the following:
- epoxy-terminated resins that is, resin having glycidyl end groups
- Formula (la) with weight-average molar mass between 2500 and 30000, preferably from 15000 to 25000.
- the epoxy resins are obtainable by reacting tetrabromobisphenol A with epichlorohydrin and then further reacting with bisphenol A.
- Commercially available examples include F-2100 from ICL-IP, with molecular weight of about 20,000 or F-3100 (end-capped) with molecular weight of about 15, 000.
- Boron phosphate (BPO4) for use in the invention is available on the marketplace from various suppliers in a powder form and can be synthesized by the reaction of equimolar amounts of phosphoric acid (H3PO4) and boric acid (H3BO3) as described, for example, in US 2,200,734 and Acta Chim. Slov. 1999 46(2) pp . 161-171. Boron phosphate is used commercially as a catalyst and has been considered as a slow-release boron fertilizer (US 3, 655,357) .
- Boron phosphate has been also mentioned as an additive for thermoplastics and was incorporated into a few polyamide- containing composition (see EP 714951) , but it appears that hitherto its combined action as an adjunct to brominated flame retardants along with CTI enhancement in polyamides has not been reported.
- CTI-enhancing amount of boron phosphate is added to the polyamide composition, for example, from 4 to 10% by weight based on the total weight of the composition.
- filler loading in polyamide formulation may be from 1 to 50%, e.g., from 5 to 40%, based on the total weight of the polyamide formulation.
- One important type of filler consists of reinforcing glass fibers, which are often pre-coated by manufacturers to improve their compatibility with the polymer in question (e.g., polyamide in the present case; for example, a silane coating) .
- the major constituents of glass fibers applied for reinforcing polyamides intended for use in electrical devices are alumino-borosilicates ; such type of glass in known as E-glass.
- the glass fibers are in the form of filaments with diameter in the range from Ip to 30p, and are applied in the form of chopped strands with length in the range from 2 to 10 mm, e.g., from 3 to 4.5 mm.
- the concentration of the glass fibers is usually from 5% to 40%, e.g., from 10% to 40%, preferably from 20% to 40%, e.g., from 25% to 35% by weight, based on the total weight of the polyamide composition.
- Preferred compositions of the invention are therefore designated PA/GF20-40 and PA/GF25-35, such as PA/GF25 and PA/GF30.
- Other common secondary fillers include glass microspheres and minerals such as talc, mica, and clay.
- Bromine content of commercially available flame retardants vary from ⁇ 50 to 80% by weight.
- the amount of bromine added to a flammable polymer upon incorporation of a brominated flame retardant is calculated by multiplying the bromine content of the flame retardant by the weight concentration of the flame retardant added to the polymer composition.
- the total concentration of the [bromine/BPCh ] in the polyamide formulation is from 18 to 30% (20 to 25%) by weight and the combination is proportioned 3:1 to 2:1, e.g., about 2.5:1 (bromine: BPO4) . That is, the concentration of bromine is adjusted in the range from 10 to 20%, e.g., 13 to 20%, e.g., 14 to 18% by weight, with not less than 5% by weight of boron phosphate, e.g., from 6 to 10% by weight, based on the total weight of the composition.
- brominated polystyrene when used as a flame retardant it is added at a concentration of not less than 21%, e.g., from 22 to 26% by weight (based on the total weight of the polyamide composition) , to supply the required bromine loading (>13%) ; BPO4 is added at a concentration of 5 to 8%.
- the BFR/BPO4 combination does not need the help of antimony-containing synergists.
- the composition of the invention is substantially antimony (e.g., Sb2O3)-free.
- substantially Sb2O3-free is meant that the concentration of antimony trioxide in the composition is well below the acceptable amount used in plastic composites in conjunction with halogenated additives, e.g., not more 1.0% by weight, more preferably, up 0.5% by weight, e.g., 0.0-0.3% by weight (based on the total weight of the composition) . Most preferably, the compositions of the invention are totally devoid of antimony trioxide .
- compositions of the invention also include one or more antidripping agents such as polytetrafluoroethylene (abbreviated PTFE) in a preferred amount between 0.1 and 1.0 wt.%, more preferably between 0.3 and 0.7 wt.%, based on the total weight of the composition.
- PTFE polytetrafluoroethylene
- compositions comprising: from 30 to 50% by weight of a polyamide (e.g., 30-45%) , for example, PA 6, 6; from 10 to 35% by weight of a reinforcing filler (e.g., 25-35%) , for example glass fibers; from 10 to 20% by weight of bromine (e.g., 13 to 20%, 14 to 18%) , supplied by a corresponding amount of bromine-containing polymer selected from the group consisting of brominated polystyrene, poly (pentabromobenzyl acrylate) and brominated epoxy resin of Formula (Ta) ; from 4 to 10% of boron phosphate (e.g., 5 to 8%) ; from 0.1 to 1.0 % (e.g., 0.3 to 0.7%) by weight of PTFE; and from 1 to 5% (e.g., 2 to 4%) by weight talc; were shown to possess especially good flammability and electrical properties.
- a polyamide e.g., 30-45%
- compositions of the invention are tested in accordance with the UL-94 flammability test, at a thickness equal to 0.8 mm (or even 0.4 mm) , V-0 rating is measured; and when tested in accordance with IEC 60112 standard using 0.1% by weight NH4CI solution and platinum electrodes, CTI of 500 V or more (e.g., 500 ⁇ CTI ⁇ 600, 550 ⁇ CTI ⁇ 600 V) is measured .
- the composition of this invention may further contain conventional additives, such as UV stabilizers, processing aids, antioxidants, lubricants, colorants, impact modifiers and the like.
- additives such as UV stabilizers, processing aids, antioxidants, lubricants, colorants, impact modifiers and the like.
- the total concentration of these auxiliary additives is typically not more than 3 % by weight, based on the total weight of the composition.
- the preparation of the polyamide compositions of the invention i.e., the blending of the polyamide and the other constituents
- the shaping of the compositions into articles may be carried out by conventional methods such as melt-mixing (to form the blend) and injection molding or extrusion molding (to transform the blend into the final article) .
- the polyamide compositions are compounded by meltmixing the components, e.g., in a co-kneader or twin-screw extruder, wherein the mixing temperature, for most polyamides, is in the range from 250 to 350°C. It is possible to feed all the ingredients to the extrusion throat together, but it is generally preferred to first dry-mix some of the components, and then to introduce the dry blend into the main feed port of the extruder, with one or more of the ingredients being optionally added downstream.
- the polyamide, the bromine containing flame retardant, boron phosphate, PTFE and talc and one or more of the conventional additives are dry blended and the blend is fed to the extruder throat, followed by the addition of glass fibers downstream.
- Process parameters such as barrel temperature, melt temperature and screw speed are described in more detail in the examples that follow.
- the resultant extrudates are comminuted into pellets.
- the dried pellets are suitable for feed to an article shaping process, e.g., injection molding and extrusion molding.
- Polyamides are readily processable by injection molding. For example, after they have been dried to minimize moisture, PA 6, 6 and PA 6 are injection molded at melt temperature in the range from 250 to 290 °C, respectively, and mold temperature is from 70 to 90 °C. Process parameters are described in more detail in the examples that follow.
- articles e.g., made of PA 6, 6 or PA 6
- electric and electronic parts in applications of power distribution (such as circuit breakers, domestic/industrial switches and sockets, contactor housing, refrigerator electronic power module housing) and insulation systems (such as coil bobbins, electrical engine insulation parts, stator housing and stator coils) ; connectivity systems and cable ties.
- the combination consisting of BFR/BPO4 was shown to be effective in reducing the flammability of polyamides, including filled polyamides such as glass reinforced PA/GF20-35, providing compositions having good electrical properties.
- Another aspect of the invention is therefore an additive mixture, comprising a bromine-containing polymer, such as brominated polystyrene, and boron phosphate (with bromine : BPO4 weight ratio preferably in the range from 3:1 to 2:1) , that is able to reduce flammability and increase CTI in antimony-free glass-reinforced thermoplastics.
- the additive mixture when used in forming a glass-reinforced thermoplastic composition, can impart a UL- 94 flammability rating of V-0 at a thickness equal to 0.8 or 0.4 mm; and when the antimony-free glass-reinforced thermoplastic composition is tested in accordance with IEC 60112 standard using 0.1% by weight NH4CI solution and platinum electrodes, the comparative CTI measured is from 500 to 600 V, e.g., 500 to 600 V.
- a direct flame test was carried out according to the Underwriters-Laboratories standard UL 94 in a gas methane operated flammability hood, applying the vertical burn on specimens of 0 . 8 mm or 0 . 4 mm thickness .
- the Notched I zod impact test was carried out according to ASTM D256- 81 using Instron Ceast 9050 pendulum impact system .
- Tensile properties were determined according to ASTM D638 using Zwick Z- 010 material testing machine ( type 2 dumbbells were used, with a speed test of 5 mm/min) .
- Heat distortion temperature ( abbreviated HDT ; this is the temperature at which a polymer sample deforms under a speci fic load) was measured according to ASTM D-648 with load of 1820 kPa and heating rate of 120°C/hour.
- the instrument was HDT/VICAT - Instron HV3S.
- CTI Comparative Tracking Index
- the strands produced were pelletized in a pelletizer 750/3 from Accrapak Systems Ltd.
- the resultant pellets were dried in a circulating air oven (Heraeus Instruments) at 120°C for 3 hours.
- the dried pellets were injection molded into 0.4 mm and 0.8 mm thick test specimens using Allrounder 500-150 from Arburg under the conditions tabulated in Table 2.
- the test specimens were conditioned for one week at 23°C and were then subjected to several tests to determine their properties. Table 2
- compositions and test results are set out in Table 3 .
- Table 3 The results tabulated in Table 3 indicate that addition of boron phosphate to glass filled polyamide 6, 6, that was flame retarded with brominated polystyrene (bromine w/w concentration of the polyamide composition is ⁇ 15%) has two positive effects: flammability rating was improved from V-2 to V-0 at 0.8 mm, and CTI increased from 475 V to 600 V (Example 1 Example 2) . Furthermore, PA 6, 6/GFso that is UL 94 V-0 rated at 0.4 mm can also be achieved at an acceptable level of added bromine (Example 3 Example 4) .
Abstract
The invention provides a polyamide composition comprising a polyamide, a brominated flame retardant and boron phosphate. The invention further relates to a method of reducing the flammability and enhancing the comparative tracking index of a polyamide to achieve UL 94 V- 0 rating and reach 500 V < CTI, by the addition of a brominated flame retardant and boron phosphate to the polyamide.
Description
Flame-retarded polyamide compositions with good electrical performance
Background of the invention
The demand for polyamide (PA) is expected to grow in view of the importance of applications such as power distribution, industrial control, insulation systems and connectivity systems. Thus, a need exists for polyamides, either unfilled or reinforced, e.g., with glass fibers (GF) , which show reduced flammability alongside good electrical and mechanical properties. We use the notation PA/GFX (for example, PA 6, 6/GFso) to indicate a polyamide that is filled with glass fibers and the concentration of the reinforcing filler, e.g., 30% by weight.
Flammability characteristics of plastics are often quantified by a method specified by Underwriter Laboratories standard UL 94, where an open flame is applied to the lowermost edge of a vertically mounted test specimen made of the tested polymer formulation. The specimens used in the UL 94 test method vary in thickness (typical thicknesses are ~3.2 mm, ~1.6 mm, ~0.8 mm and ~0.4mm) . During the test, various features of the flammability of the test specimens are recorded. Then, according to the classification requirements, the polymer formulation is assigned with either V-0, V-l or V-2 rating at the measured thickness of the test specimen. Polymer formulation assigned with the V-0 rating is the least flammable. In the UL-94 burning test, the thinner the specimens are, the longer the burning time.
One approach towards reducing the flammability of polyamides, to achieve UL 94 V-0 ratings at 0.4-0.8 mm wall thickness, is by the addition of a brominated flame retardant. Generally, the performance of brominated flame retardants depends heavily on the inclusion of antimony trioxide (Sb2Os) in the flammable polymer. Antimony trioxide acts as a synergist to enhance the
action of the brominated flame retardant. Hence, Sb20s often accompanies the brominated flame retardant in many polymeric formulations, and polyamide is no exception. Such polyamide formulations, that are described for example by Weil and Levchik in "Current Practice and Recent Commercial Developments in Flame Retardancy of Polyamides" (Journal of Fire Science, Vol. 22, 2004, p.251-263) show that flame retardation of polyamides with the brominated flame retardant /Sb2O3 system is quite efficient, with filled polyamides (e.g., PA 6, 6/GFso) achieving UL-94 V- 0/0.8 mm rating at a reasonable loading of the flame retardant system.
However, the electrical properties of bromine-added polyamides are often not satisfactory, e.g., to serve as insulating materials with high tracking resistance that are required for many applications. The electrical breakdown property is quantified using the Comparative Tracking Index (CTI) , which is a measure of the susceptibility of solid insulating materials to surface tracking when exposed to an electrolyte under the application of voltage. CTI indicates the voltage which causes the sample to undergo carbonization. CTI is measured according to IEC 60112 with standard 0.1% NH4CI electrolyte solution; see experimental section below. The higher the CTI the better the resistance of the sample to electrical discharge etc. The maximum voltage applied in the IEC 60112 method is 600 V. But many commercial polyamide grades, e.g., PA 6, 6/GF2o-3o, that are formulated with brominated flame retardants to get UL 94 V-0 rating at 0.4 or 0.8 mm, possess relatively low CTI, i.e., of less than 400 V (https://docplayer.net/163527753-For-the- electrical-electronic-markets.html; see Chart 2) .
It was recently shown in US 2020/0115551 that unfilled polyamide can be formulated with a brominated flame retardant to achieve UL 94 V-0 rating at a thickness as low as 0.4 mm in the absence
of Sb2O3, reaching CTI of 550 V. However, to offset the omission of the powerful Sb2O3 synergist, a non-halogenated flame retardant was added to the polyamide (Examples 3-5 of US 2020/0115551) .
Thus, there exists a need for a bromine-based flame-retardant system that can be added to polyamide, to effectively reduce the flammability of polyamide formulations, especially filled polyamide grades, such as PA 6, 6/GFIS-35 formulations, to achieve UL 94 V-0 at 0.8 mm thickness or less, and at the same time enhance the CTI of the polyamide.
The invention
Experimental work reported below shows that the use of a brominated flame retardant (BFR) in combination with boron phosphate (BPO4) confers the desired flammability and electrical properties on polyamides. Notably, polyamides such as PA 6, 6/GF3o can be flame retarded effectively with the aid of the abovementioned combination in the absence of antimony trioxide. The BFR/BPO4 combination performs well at reasonable concentrations in polyamides to achieve UL 94 V-0 rating, comparable to the concentrations of the BFR/Sb2O3 combination that are recommended for the same purpose. The difference is seen in the electrical properties; the experimental results shown below indicate that polyamide formulations of the invention reach CTI as high as 600 V.
Accordingly, the invention is primarily directed to a polyamide composition comprising a polyamide, a brominated flame retardant and boron phosphate (or boron pyrophosphate, or boron polyphosphate) . The invention also relates to a method of reducing the flammability and enhancing the comparative tracking index of a polyamide to achieve UL 94 V-0 rating and reach 500 < CTI < 600 V, e.g., 550 < CTI < 600 V, which method comprises
adding a brominated flame retardant and boron phosphate to the polyamide .
The polyamides for use in the invention are of course commercially available and can be prepared by well-known methods, e.g., polycondensation reactions of dibasic carboxylic acids and diamines (or amino-carboxylic acid) and ring-opening polymerization of lactams, that are described, for example, in Nylon Plastics Handbook M., ed. I. Kohan, 1995, Munich, Hanser.
The monomers used in the preparation of polyamides by polycondensation reactions are aliphatic and/or aromatic dicarboxylic acids and aliphatic and/or aromatic diamines, hence the polyamides may be wholly aliphatic/cycloaliphatic, wholly aromatic or mixed aliphatic-aromatic. Major dicarboxylic acid monomers include adipic acid, 2,2,4 and 2 , 4 , 4-trimethyl adipic acid, azelaic acid, sebacic acid, 1 , 1 O-decanedicarboxylic acid, 1 , 12-dodecanedioic acid, isophthalic acid and terephthalic acid. Major diamine monomers include hexamethylenediamine, tetramethylenediamine, 2,2,4- trimethyl hexamethylenediamine, 2 , 4 , 4-trimethyl hexamethylenediamine, 1 , 4-diaminobutane, 1,12- dodecanediamine and xylylenediamine . As an example of aminocarboxylic acids, 11-amino undecanoic acid could be mentioned.
For example, aliphatic polyamides obtained by polycondensation reactions of dibasic acid HO2C (CH2) xCChH and diamine NH2(CH2)yNH2 can be used in the invention. PA 6,6 is produced this way (x=4, y=6, i.e., from adipic acid and hexamethylenediamine; namely, poly (hexamethylene-adipamide ) .
As mentioned above, another commercially important process to obtain aliphatic polyamides is the ring-opening polymerization of lactams, such as the polymerization of caprolactam to give PA 6 (polycaprolactam) , which takes place in water with cationic or
anionic initiator. Other useful lactam monomers besides caprolactam include capryllactam and lauryllactam.
Thus, specific polyamides that can be used in the invention, obtainable by the synthetic methods set out above, are aliphatic polyamides such as PA 6, 6, PA 6, PA 6,9, PA 6,10, PA 6,12, PA 11, PA 12, PA 12,12, PA 4, 6 and partially aromatic polyamides such as polyxylylene adipamide and polyphthalamides formed by the reaction of ferephthalic acid/ Isophthalic acid with aliphatic diamines, such as hexamethylene diamine.
The concentration of the polyamide in the composition of the invention is from 30 to 80 % by weight, e.g., in filled grades it may vary in the range from 30 to 60% and in unfilled grades it is usually from 60 to 80% (based on the total weight of the composition) . The term polyamides, as used herein, includes copolyamides, such as those described in length in US 2020/0115551, e.g., the polymerization product of diamine (for example, hexamethylenediamine) , dibasic acid (for example, adipic acid) and a monomer capable of self-condensation (for example, caprolactam) to form a co-polyamide such as PA 6, 6/6. Polyamide blends, obtained for example by melt-mixing in an extruder two types of polyamides, such as PA 6, 6 and PA 6, to give PA 6, 6 + PA 6 blend (PA 6, 6 is usually the predominant component) can also benefit from the invention.
The brominated flame retardant added to the polyamide is preferably a bromine-containing polymer. Different types of bromine-containing polymers can be used, for example: i) Brominated polystyrene, having the following formula:
(n=degree of polymerization; m= 1,2, 3, 4 or 5)
Brominated polystyrene is prepared by methods known in the art (see US 4,879,353 and US 5,532,322) . Suitable grades have weight average molecular weight in the range of about 500, 000-600,000, with bromine content preferably exceeding 60 or even 65 % by weight e.g., 66% (that is, average of 2-3 bromine atoms per aromatic ring in the polymer backbone chain) . Such brominated polymers, in the form of a free-flowing powder or in granular form, are available on the market, e.g., from ICL-IP (FR 803P) . ii) Poly (pentabromobenzyl acrylate) , represented by the following formula:
(n=degree of polymerization)
The polymer (abbreviated PBBPA) is produced by polymerizing the corresponding monomer pentabromobenzyl acrylate, either in bulk (in an extruder at a temperature in the range from 120°C to 290°C as described in US 4,996,276) , or in solution, see US 4,128,709 or 6,028,156. The polymer is also available on the marketplace, being sold by ICL-IP (FR-1025) .
iii) brominated epoxy resins and end-capped derivatives thereof, represented by the Formula (I) :
(m=degree of polymerization) ; wherein Ri and R2 are independently selected from the group consisting of the following:
Preferred are epoxy-terminated resins (that is, resin having glycidyl end groups) represented by Formula (la) :
with weight-average molar mass between 2500 and 30000, preferably from 15000 to 25000. The epoxy resins are obtainable by reacting tetrabromobisphenol A with epichlorohydrin and then further reacting with bisphenol A. Commercially available examples include F-2100 from ICL-IP, with molecular weight of about 20,000 or F-3100 (end-capped) with molecular weight of about 15, 000.
Boron phosphate (BPO4) for use in the invention is available on the marketplace from various suppliers in a powder form and can be synthesized by the reaction of equimolar amounts of phosphoric acid (H3PO4) and boric acid (H3BO3) as described, for example, in US 2,200,734 and Acta Chim. Slov. 1999 46(2) pp . 161-171. Boron phosphate is used commercially as a catalyst and has been considered as a slow-release boron fertilizer (US 3, 655,357) . Boron phosphate has been also mentioned as an additive for thermoplastics and was incorporated into a few polyamide- containing composition (see EP 714951) , but it appears that hitherto its combined action as an adjunct to brominated flame retardants along with CTI enhancement in polyamides has not been reported. CTI-enhancing amount of boron phosphate is added to the polyamide composition, for example, from 4 to 10% by weight based on the total weight of the composition.
Both unfilled and filled polyamides could benefit from the invention. The addition of fillers improves the mechanical properties of the polymer. Filler loading in polyamide formulation may be from 1 to 50%, e.g., from 5 to 40%, based on the total weight of the polyamide formulation. One important type of filler consists of reinforcing glass fibers, which are often pre-coated by manufacturers to improve their compatibility with the polymer in question (e.g., polyamide in the present case; for example, a silane coating) . The major constituents of glass fibers applied for reinforcing polyamides intended for use in electrical devices are alumino-borosilicates ; such type of glass in known as E-glass. The glass fibers are in the form of filaments with diameter in the range from Ip to 30p, and are applied in the form of chopped strands with length in the range from 2 to 10 mm, e.g., from 3 to 4.5 mm. The concentration of the glass fibers is usually from 5% to 40%, e.g., from 10% to 40%, preferably from 20% to 40%, e.g., from 25% to 35% by weight, based on the total weight of the polyamide composition. Preferred
compositions of the invention are therefore designated PA/GF20-40 and PA/GF25-35, such as PA/GF25 and PA/GF30. Other common secondary fillers include glass microspheres and minerals such as talc, mica, and clay.
Bromine content of commercially available flame retardants vary from ~50 to 80% by weight. The bromine content of the brominated flame retardants mentioned above (FR-803P, FR-1025 and F-2100) are Br FR-803P= 6%, Br FR-IO25=71% and Br F-21OO=52% . It is convenient to express the loading of a brominated flame retardant in a flammable polymer by reporting the amount of bromine supplied by the flame retardant to the polymer. The amount of bromine added to a flammable polymer upon incorporation of a brominated flame retardant is calculated by multiplying the bromine content of the flame retardant by the weight concentration of the flame retardant added to the polymer composition.
The experimental results reported below show that to achieve satisfactory reduction in flammability and appreciable CTI enhancement in filled polyamide such as glass reinforced polyamide, the total concentration of the [bromine/BPCh ] in the polyamide formulation is from 18 to 30% (20 to 25%) by weight and the combination is proportioned 3:1 to 2:1, e.g., about 2.5:1 (bromine: BPO4) . That is, the concentration of bromine is adjusted in the range from 10 to 20%, e.g., 13 to 20%, e.g., 14 to 18% by weight, with not less than 5% by weight of boron phosphate, e.g., from 6 to 10% by weight, based on the total weight of the composition.
For example, when brominated polystyrene is used as a flame retardant it is added at a concentration of not less than 21%, e.g., from 22 to 26% by weight (based on the total weight of the polyamide composition) , to supply the required bromine loading (>13%) ; BPO4 is added at a concentration of 5 to 8%.
As mentioned above, the BFR/BPO4 combination does not need the help of antimony-containing synergists. The composition of the invention is substantially antimony (e.g., Sb2O3)-free. By "substantially Sb2O3-free" is meant that the concentration of antimony trioxide in the composition is well below the acceptable amount used in plastic composites in conjunction with halogenated additives, e.g., not more 1.0% by weight, more preferably, up 0.5% by weight, e.g., 0.0-0.3% by weight (based on the total weight of the composition) . Most preferably, the compositions of the invention are totally devoid of antimony trioxide .
The compositions of the invention also include one or more antidripping agents such as polytetrafluoroethylene (abbreviated PTFE) in a preferred amount between 0.1 and 1.0 wt.%, more preferably between 0.3 and 0.7 wt.%, based on the total weight of the composition. PTFE is described, for example, in US 6, 503, 988.
For example, compositions comprising: from 30 to 50% by weight of a polyamide (e.g., 30-45%) , for example, PA 6, 6; from 10 to 35% by weight of a reinforcing filler (e.g., 25-35%) , for example glass fibers; from 10 to 20% by weight of bromine (e.g., 13 to 20%, 14 to 18%) , supplied by a corresponding amount of bromine-containing polymer selected from the group consisting of brominated polystyrene, poly (pentabromobenzyl acrylate) and brominated epoxy resin of Formula (Ta) ; from 4 to 10% of boron phosphate (e.g., 5 to 8%) ; from 0.1 to 1.0 % (e.g., 0.3 to 0.7%) by weight of PTFE; and from 1 to 5% (e.g., 2 to 4%) by weight talc;
were shown to possess especially good flammability and electrical properties. That is, when compositions of the invention are tested in accordance with the UL-94 flammability test, at a thickness equal to 0.8 mm (or even 0.4 mm) , V-0 rating is measured; and when tested in accordance with IEC 60112 standard using 0.1% by weight NH4CI solution and platinum electrodes, CTI of 500 V or more (e.g., 500 < CTI < 600, 550 < CTI < 600 V) is measured .
Apart from the polyamide matrix, the reinforcing amount of glass fibers, the combination BFR/BPO4, an anti-dripping agent and a secondary mineral filler such as talc, the composition of this invention may further contain conventional additives, such as UV stabilizers, processing aids, antioxidants, lubricants, colorants, impact modifiers and the like. The total concentration of these auxiliary additives is typically not more than 3 % by weight, based on the total weight of the composition.
The preparation of the polyamide compositions of the invention (i.e., the blending of the polyamide and the other constituents) , and the shaping of the compositions into articles may be carried out by conventional methods such as melt-mixing (to form the blend) and injection molding or extrusion molding (to transform the blend into the final article) .
For example, the polyamide compositions are compounded by meltmixing the components, e.g., in a co-kneader or twin-screw extruder, wherein the mixing temperature, for most polyamides, is in the range from 250 to 350°C. It is possible to feed all the ingredients to the extrusion throat together, but it is generally preferred to first dry-mix some of the components, and then to introduce the dry blend into the main feed port of the extruder, with one or more of the ingredients being optionally
added downstream. For example, the polyamide, the bromine containing flame retardant, boron phosphate, PTFE and talc and one or more of the conventional additives are dry blended and the blend is fed to the extruder throat, followed by the addition of glass fibers downstream. Process parameters such as barrel temperature, melt temperature and screw speed are described in more detail in the examples that follow.
The resultant extrudates are comminuted into pellets. The dried pellets are suitable for feed to an article shaping process, e.g., injection molding and extrusion molding. Polyamides are readily processable by injection molding. For example, after they have been dried to minimize moisture, PA 6, 6 and PA 6 are injection molded at melt temperature in the range from 250 to 290 °C, respectively, and mold temperature is from 70 to 90 °C. Process parameters are described in more detail in the examples that follow.
Articles molded from the polyamide compositions, especially thin-walled parts, form another aspect of the invention. Specific examples of articles (e.g., made of PA 6, 6 or PA 6) include electric and electronic parts, in applications of power distribution (such as circuit breakers, domestic/industrial switches and sockets, contactor housing, refrigerator electronic power module housing) and insulation systems (such as coil bobbins, electrical engine insulation parts, stator housing and stator coils) ; connectivity systems and cable ties.
The combination consisting of BFR/BPO4 was shown to be effective in reducing the flammability of polyamides, including filled polyamides such as glass reinforced PA/GF20-35, providing compositions having good electrical properties. Another aspect of the invention is therefore an additive mixture, comprising a bromine-containing polymer, such as brominated polystyrene, and
boron phosphate (with bromine : BPO4 weight ratio preferably in the range from 3:1 to 2:1) , that is able to reduce flammability and increase CTI in antimony-free glass-reinforced thermoplastics. That is, when used in forming a glass-reinforced thermoplastic composition, the additive mixture can impart a UL- 94 flammability rating of V-0 at a thickness equal to 0.8 or 0.4 mm; and when the antimony-free glass-reinforced thermoplastic composition is tested in accordance with IEC 60112 standard using 0.1% by weight NH4CI solution and platinum electrodes, the comparative CTI measured is from 500 to 600 V, e.g., 500 to 600 V.
Examples
Materials and methods
The materials used for preparing the PA 6 , 6/GFso formulations are tabulated in Table 1 ( FR is abbreviation of flame retardant ) :
Flammability properties
A direct flame test was carried out according to the Underwriters-Laboratories standard UL 94 in a gas methane operated flammability hood, applying the vertical burn on specimens of 0 . 8 mm or 0 . 4 mm thickness .
Mechanical properties
The Notched I zod impact test was carried out according to ASTM D256- 81 using Instron Ceast 9050 pendulum impact system . Tensile properties were determined according to ASTM D638 using Zwick Z- 010 material testing machine ( type 2 dumbbells were used, with a speed test of 5 mm/min) .
Thermal properties
Heat distortion temperature ( abbreviated HDT ; this is the temperature at which a polymer sample deforms under a speci fic
load) was measured according to ASTM D-648 with load of 1820 kPa and heating rate of 120°C/hour. The instrument was HDT/VICAT - Instron HV3S.
Electrical properties
Comparative Tracking Index (CTI) was measured according to the International Electrotechnical Commission (IEC) STANDARD publication 112 (DIN EN 60112) . The test was performed with a solution of NH4CI 0.1% (solution A) and Pt electrodes.
Examples 1 (comparative) and 2 to 4 (of the invention)
PA 6,6/GFso formulations
To prepare the formulations tabulated in Table 3, PA 6, 6 and the additives (with the exception of the glass fibers) were preblended and the blend was fed via Feeder no. 1 into the main port of a twin-screw co-rotating extruder ZSK-18-ML (Coperion) . The glass fibers were added downstream, via Feeder no. 3 to the seventh zone of the barrel through a lateral feeder. The twin screw extruder was operated with barrel temperature profile of 235°C, 260°C, 260°C, 265°C, 265°C, 270°C, 275°C, die - 280°C, applying a screw rotation speed of 500-900 rpm and feeding rate of 8-10 kg/hour.
The strands produced were pelletized in a pelletizer 750/3 from Accrapak Systems Ltd. The resultant pellets were dried in a circulating air oven (Heraeus Instruments) at 120°C for 3 hours. The dried pellets were injection molded into 0.4 mm and 0.8 mm thick test specimens using Allrounder 500-150 from Arburg under the conditions tabulated in Table 2. The test specimens were conditioned for one week at 23°C and were then subjected to several tests to determine their properties.
Table 2
The compositions and test results are set out in Table 3 .
Table 3
The results tabulated in Table 3 indicate that addition of boron phosphate to glass filled polyamide 6, 6, that was flame retarded with brominated polystyrene (bromine w/w concentration of the polyamide composition is ~15%) has two positive effects: flammability rating was improved from V-2 to V-0 at 0.8 mm, and CTI increased from 475 V to 600 V (Example 1 Example 2) . Furthermore, PA 6, 6/GFso that is UL 94 V-0 rated at 0.4 mm can also be achieved at an acceptable level of added bromine (Example 3 Example 4) .
Claims
Claims
1) A polyamide composition comprising a polyamide, a brominated flame retardant and boron phosphate.
2) The polyamide composition according to claim 1, which is a glass reinforced polyamide.
3) The polyamide composition according to any one of the preceding claims, wherein the brominated flame retardant is a bromine-containing polymer.
4) The polyamide composition according to claim 3, wherein the bromine-containing polymer is brominated polystyrene.
5) The polyamide composition according to any one of the preceding claims, wherein the polyamide is PA 6, 6.
6) The polyamide composition according to any one of the preceding claims, wherein the total concentration of a combination consisting of bromine and boron phosphate is from 18 to 30% by weight based on the total weight of the composition, wherein the combination [bromine: BPO4] is proportioned around 3:1 to 2:1 by weight.
7) The polyamide composition according to any one of the preceding claims, wherein the concentration of bromine is adjusted in the range from 13 to 20% with not less than 5% by weight of boron phosphate, based on the total weight of the composition .
8) The polyamide composition according to any one of the preceding claims which is substantially antimony-free.
9) A polyamide composition according to any one of the preceding claims, comprising: from 30 to 50% by weight of a polyamide; from 10 to 35% by weight of glass fibers; from 10 to 20% by weight of bromine, supplied by a corresponding amount of a bromine-containing polymer selected from the group consisting of brominated polystyrene, poly (pentabromobenzyl acrylate) and brominated epoxy resin of Formula (la) ; from 4 to 10% by weight of boron phosphate; from 0.1 to 1.0 % by weight of PTFE; and from 1 to 5% by weight talc.
10) A polyamide composition according to claim 9, wherein the polyamide is PA 6, 6 and the bromine-containing polymer is brominated polystyrene.
11) A polyamide composition according to any one of the preceding claims, which when tested in accordance with the UL-94 flammability test, at a thickness equal to 0.8 mm or 0.4 mm, V-0 rating is measured; and when tested in accordance with IEC 60112 standard using 0.1% by weight NH4CI solution and platinum electrodes, CTI of 500 V or more is measured.
12) A polyamide composition according to claim 11, wherein CTI above 550 V is measured.
13) A method of reducing the flammability and enhancing the comparative tracking index of a polyamide to achieve UL 94 V-0 rating and reach 500 V < CTI, which method comprises adding a brominated flame retardant and boron phosphate to the polyamide.
14) A method of reducing the flammability and enhancing the comparative tracking index of a polyamide according to claim 13, reaching 550 V < CTI < 600 V.
15) A method according to claim 12 or 14, wherein the polyamide is glass reinforced PA 6, 6 and the brominated flame retardant is brominated polystyrene.
16) A method according to claim 15, wherein the brominated polystyrene and the boron phosphate are added to the polyamide such that the weight ratio bromine : BPO4 is in the range from 3:1 to 2:1.
17) An additive composition, comprising a mixture of brominecontaining polymer and boron phosphate with bromine : BPO4 weight ratio in the range from 3:1 to 2:1, that is able to reduce flammability and increase CTI in antimony-free glass-reinforced thermoplastics .
18) An additive composition according to claim 17, wherein the bromine-containing polymer is brominated polystyrene.
19) An article molded from the polyamide composition of any one of the claims 1 to 12.
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