Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-01-27
1994-08-16
Morgan, Kriellion S.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524405, C08K 338
Patent
active
053387910
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fire-retardant polymer compositions, and preferably, but not exclusively, to fire-retardant polyamide compositions. It will be understood by those in the art that the term "fire-retardant" encompasses "flame-retardant".
The use of zinc borate or zinc stannate as components of fire-retardant compositions is well known in the art. The use of zinc borate is described in U.S. Pat. No. 4,360,616 and U.S. Pat. No. 4,504,611.
U.S. Pat. No. 4,360,616 describes a glass-reinforced flame-retardant polyamide composition having good arc tracking resistance and consisting of: melamine derivative. compound obtained from the condensation of two moles of perchloro-cyclopentadiene and one mole of 1,5-cyclooctadiene, or a brominated polystyrene,
U.S. Pat. No. 4,504,611 similarly describes a flame-retardant polyamide consisting, in percent by weight, of:
Although there is disclosure of the use of a zinc borate with zinc oxide, there is no reference in this prior art to the use of zinc stannate.
It has now been found that the combination of a zinc borate and a divalent metal stannate, particularly zinc stannate, in halogen-containing polymeric compositions provides an increased fire-retardant effect, which is greater than that expected from the use of either zinc borate or the stannate alone. The combination also suppresses smoke production. Where the term "stannate" is used herein in a general sense it includes "hydroxy stannate" in view of their similar fire-retardant properties.
According to the present invention, there is provided a fire-retardant polymer composition comprising a polymer and a fire-retardant amount of a mixture of a zinc borate and a divalent metal stannate, wherein the composition includes a source of halogen.
The source of halogen can be the polymer itself or can be a separate component, such as an organic halogen-containing fire-retardant, provided that the component is compatible with the polymer.
Preferably the fire-retardant compositions of the present invention comprise, by weight percent: preferably in a weight percentage ratio of between 10:90 and 90:10, more preferably of the order of 50:50.
Examples of suitable stannates that can be used are zinc stannate, zinc hydroxystannate, calcium hydroxystannate and magnesium hydroxystannate. Preferably the stannate is zinc stannate.
The constitution of zinc borate is variable as is described in the paper entitled "Applications of zinc borate in polymer blends and alloys" by W. J. Kennelly in the report of the Proceedings of the Fire Retardant Chemicals Association meeting held at Hilton Head Island, S.C., Mar. 17th to 20th 1991 pages 199 to 205.
Whilst any zinc borate can be used, that of the formula 2ZnO.sub.2. 3B.sub.2 O.sub.3. 3.5H.sub.2 O--known as "ZB 2335"--is preferred and is the borate that is intended in this specification unless indicated to the contrary.
Examples of suitable polymers include polyesters, epoxy resins, ABS combinations and the like, but preferably, a polyamide is used. Halogenated polymers such as PVC can also be used in this invention and since they act as a source of halogen no separate halogen-containing component is needed.
Polyamides are thermoplastic compounds, constructed of the bifunctional monomers, dicarboxylic acid and diamine, the properties of which are related to the length of the hydrocarbon radicals. One general class of polyamides used in the present invention is "nylon".
One example of nylon is polyhexamethylene adipamide (Nylon 66) formed by condensing hexamethylene diamine and adipic acid. Other examples include polyhexamethylene azelaamide (Nylon 69), polyhexamethylene sebacamide (Nylon 610), polylauric lactam, polycaprolactam (Nylon 6), poly-11-aminoundecanoic acid and poly-bis-(4-aminocyclohexyl) methane dodecanoamide.
The organic halogen-containing fire-retardant used can be any of those known in the art, such as those described in U.S. Pat. No. 4,360,616 and U.S. Pat. No. 4,504,611, particularly that sold under the trade mark Dechlorane. Other examples include poly-dibromo-phenyl
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Alcan International Limited
Morgan Kriellion S.
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