Note: Descriptions are shown in the official language in which they were submitted.
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LOW- Pl.UlMa~ILITY COPOLYAMIDES
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R~.'W"~IINI. OP TE~ lNVL llON
1. Fleld of he In~rent$on
The invention relates to a copolyamide composition which
ha~ a reduced flammability and which is transparent, and
method~of producing same, to a molded article produced from
the copolyamide composltion, and to use of a flame-retardant
additive to reduce flammability of the copolyamide
composition and the article molded therefrom. In particular,
the invention relates to use of a flame-retardant additive
comprised of at least one alkyl phoæphoric acid compound to
reduce flammability of the copolyamide com~osition and the
articlè molded therefrom.
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.2. Des~cril~tion of the Related Art
Flame-retardant additives for polymers, especially
polyamides, are well-known prior art. These include melamine
compounds, especially melamine cyanurate, magnesium and
aluminum hydroxide, halogenated and especially brominated
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~ organic compounds, especially in combination with heavy metal
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salts, and phosphorus alone and in combination with halogen-
containing compounds.
These additives are unsuitable for use with transparent
polyamide and copolyamide compositions, however, because they
are deleterious to the transparency of such composltions and
articles molded therefrom.
It is therefore an object of the present invention to
provide a transparent, low-flammability copolyamide
composltion.
It iB another object of the present invention to provide
a transparent, low-flammability article molded from the
foregoing transparent, low-flammability copolyamide
composition. --
It is yet another object of the present invention to
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provide a method of producing a molded article which has
reduced fl~mmAhility and which is transparent from the
foregoing transparent, low-flammability copolyamide
compDs i tion.
It is still another object of the present invention to
provLde a method of reducing flammability of a transparent
copolyamide and of a molded article which is molded from the
foregoing copolyamide composition.
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SUMMA~Y OF THE lN V~ ON
These objects are attained by the present invention
which provides a copolyamlde composition which has a reduced
flammability and which is transparent. The copolyamide
composition comprises at least one copolyamide and a flame-
retardant additive comprised of at least one alkyl phosphoric
acid compound which is dissolved in the at least one
copolyamide and which is present in an amount effective to
reduced flammability of the copolyamide composition.
The at least one alkyl phosphoric acid compound is
advantageously present in an amount ranging from about 0.5 to
about 40.0 weight ~, preferably from about 4.0 to about 10.0
weight ~, based on the weight of the at least- one
copolyamide.
The at least one copolyamide is advantageously based on
at least one monomer selected from the group consisting of PA
6, PA 11, and PA 12. The at least one copolyamide is
preferably based on at least one first monomer selected from
the group consisting of (a) aliphatic diamines having from 4
to 12 carbon atoms, ~b) cycloaliphatic diamines having from 7
to 22 carbon atoms, and (c~ aromatic diamines having from 6
to 22 carbon atoms, in combination with at least one second
monomer selected from the group consisting of (d) aliphatic
dicarboxylic acids havlng from 4 to 36 carbon atoms, (e)
cycloaliphatic dicarboxylic acids having from 8 to 24 carbon
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atoms, and (f) aromatic dicarboxylic acids having from 8 to
20 carbon atoms. In particular, the at least one copolyamide
is a blend of a plurality of copolyamides which are
transparent.
The flame-retardant additive is preferably an ester of
an aliphatic polyol and an alkylated phosphoric acid, such as
a trimethyl propanol ester of a methyl phosphoric acid.
The objects of the present invention are additionally
attained by providing a molded article which has reduced
flammability, which is transparent, and which is comprised of
the foregoing copolyamide composition.
The objects of the present invention are additionally
attained by providing a method of producing -a molded article
which has reduc~d flammability and which is transparent. The
method includes the steps of (a) preparing a copolyamide
composition for molding by adding to at least one copolyamide
a flame-retardant additive comprised of at least one alkyl
phosphoric acid compound which is dissolved in the
copolyamide and which is added in an amount effective to
reduce flammability; and (b) molding the copolyamide
composition to provide the molded article.
The objects of the present invention are additionally
attained by reducing flammability of a copolyamide
composition or of a molded article which is molded from a
copolyamide composition using addition to at least one
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copolyamide a flame-retardant additive comprising at least
one alkyl phosphoric acid compound which is dissolved in the
copolyamide and which is present in an amount effective to
reduce flammability thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It is a special advantage of the present invention that
the copolyamide compositions are characterized by having very
little or no migration of the dissolved phosphoric acid
compounds. Hence, molded articles made from the copolyamide
compositions of the invention have no annoying deposits as
have been known to form on prior art molded articles molded
from copolyamide compositions containing fla~e-retardant
additives previously known and employed in the art.
Another advantage of the present invention is that the
mechanlcal properties of the copolyamides or molded articles
made from the copolyamides are virtually unchanged by the
dissolved flame-retardant additives according to the
invention.
It is also especially advantageous that the copolyamides
of the invention are already substantially flame-retardant
even when modified with additive amounts which are relatively
low and range from 4 to 10 weight ~. Transparent
copolyamides having from 0.5 to 40 parts by weight of at
least one alkyl phosphoric acid compound are suitable to
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produce reduced flammability according to the present
invention. However, an additive amount of 4 weight ~ or more
is generally preferred in order to achieve a desirable VO in
the Standard UL Burning Test.
For example, a copolyamide composition containing a
copolyamide of the type PA 61/MACM T or of the type PA
12/MACM I was prepared and it was determined that 5 weight
of the flame-retardant additive was necessary in order to
achieve 94 V, in the Standard UL Burning Test. The flame-
retardant tested was a trimethyl propanol ester of a methyl
phosphoric acid.
Copolyamides that are suitable copolyamides according to
the invention are ~hose that are condensed f-~om the monomers
of PA 6, PA 11 or PA 12, or aliphatic diamines having from 4
to 12 carbon atoms, cycloaliphatic diamines having from 7 to
22 carbon atoms, or aromatic or araliphatic diamines having
from 6 to 22 carbon atoms and aliphatic dicarboxylic acids
having from 4 to 36 carbon atoms, cycloaliphatic dicarboxylic
acids having from 8 to 24 carbon atoms, and aromatic
dicarboxylic acids having from 8 to 20 carbon atoms. The
copolyamides may a-so be blends of a plurality of
copolyamides or copolyamides with semicrystalline polyamides,
as long as they are transparent. The flame-retardant
additive suitable or the present invention is at least one
alkyl phosphoric acid compound, such as an aliphatic polyol
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ester of an alkylated phosphoric acid. The trimethyl
propanol ester of a methyl phosphoric acid of the formula
each of R and Rl is an
o o o o
P~ ~C-CH2 - o -~!-o-cl~2-c~ 2 ~. alkylgroup having
O - CH2~ ¦ I I CH2 _ 0~ I
R R ' R R ' 1~ 2 to 4 C-atoms
is a preferred additive. --
Molded articles made from the transparent copolyamide
compositions of the present invention are transparent and
have low-flammability. Moreover, they are not limited in
their shape or length, especially since the mechanical
properties are not affected by the proportional amounts of
flame-retardant additive in the copolyamide. That is, an -
additive amount of 4 weigth ~ or more, especially 5 weight
to lO weigth ~ is generally preferred in order to achieve a
desirable VO in the Standard UL Burning Test, does not affect
the value of the mechanical properties.
The invention has been described in detail with re-
spect to preferred embodiments, and it will now be apparent
from the foregoing to those skilled in the art that changes
and modifications may be made without departing from the
invention in its broader aspects, and the invention,
therefore, as defined in the appended claims is intended to
cover all such changes and modifications as fall within the
true spirit of the invention.
Concerning to ISO-Standard 1874-1 PA 6I/MACMT is a co-
polyamide of hexamethylene/diamine (6), isophthalic acid (I),
3.3'-dimethyl-4.4'-diamino dicyclohexyl methane (MACM) and
terephthalic acid (T), while PA 12/MACMI is a copolyamide of
dodecanelactam, MACM and I.
