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...
Reexamination Certificate
2001-09-26
2004-01-06
Wu, David W. (Department: 1713)
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...
C524S401000, C524S404000, C524S414000, C524S430000, C524S432000, C524S544000, C525S326300
Reexamination Certificate
active
06673866
ABSTRACT:
The present invention relates to thermoplastic compositions of fluoropolymers having a reduced smoke release when subjected to a heat source. Said thermoplastic compositions are used in the “plenum wire insulation” and “cable jacketing” field, where lower and lower values of “average smoke” and “peak smoke” according to the UL910 Steiner Tunnel test are required.
More specifically the present invention relates to thermoplastic compositions of fluoropolymers of ethylene (E) with tetrafluoroethylene (TFE), and/or chlorotrifluoroethylene (CTFE), modified with one or more hydrogenated monomers.
Said fluoropolymers are used in the manufacture of flexible cables. An essential feature of these fluoropolymers consists in that they do not show a “necking at yield” on the stress-strain curve, thus avoiding the “whitening” effect on the bent cable, which visually represents the permanent plastic deformation suffered by the material.
From EP 866, 079 in the name of the Applicant, copolymers of ethylene with tetrafluroethylene and/or chlorotrifluoroethylene, modified with hydrogenated monomers, are known, the flexibility (low elastic modulus) is conferred by formulating them in compositions comprising hydrogenated plasticizers. These compositions when subjected to a heat source show a substantial decrease of smoke when the inorganic fire-retardants described in EP 906,934 in the name of the Applicant.
However in the various industrial applications, for example cable jacketing, compositions with lower and lower smoke emissions are required for clear safety reasons. Furthermore the rules regulating smoke emission become more and more restrictive in various Countries.
Therefore a further lowering of the “average smoke” and “peak smoke” values with respect to the materials of the prior art is desired and required by the cable industry.
The need was felt to have available fluorinated polymer compositions based on ECTFE or ETFE, showing a reduced smoke release, determined as “average smoke” and as “peak smoke” according to UL910 Steiner Tunnel, with respect to those of the prior art, so that it were possible to use said compositions as jacketing in cables containing primary cables formed of various materials (hydrogenated polymers, for example polyethylene, and/or fluorinated polymers, for example TFE-hexa-fluoropropene copolymers (FEP)) which were more reliable in case of fire.
The Applicant has surprisingly and unexpectedly found that by using in polymer compositions comprising ECTFE or ETFE polymers modified with hydrogenated monomers, fire-retardants agents together with crosslinking agents, it is possible to obtain compositions having a lower smoke release, determined both as “average smoke” and as “peak smoke” (UL910 Steiner Tunnel), with respect to those of the compositions of the prior art.
An object of the present invention is a polymer composition formed by:
I) fluoropolymers selected from one or more of the following: copolymers based on ethylene, TFE and/or CTFE, modified with hydrogenated monomers, or blends of these fluoropolymers with homopolymers of CTFE or (co)polymers based on CTFE (PCTFE) containing at least 99% by moles of CTFE, the complement to 100 being one or more fluorinated monomers or hydrogenated monomers; said fluoropolymers and/or the corresponding blends optionally mixed with hydrogenated plasticizers;
II) one or more inorganic fire-retardants, optionally treated with dispersing agents;
III) one or more crosslinking agents;
IV) optional additives such as fillers, “intumescent agents”, pigments, lubricants, organic “fire-retardants” and thermal stabilizers.
More specifically the fluoropolymers component I) of the composition object of the invention are formed by the following monomers:
(a) ethylene from 10 to 70%, preferably from 35 to 55% by moles;
(b) a fluorinated monomer selected from tetrafluoroethylene, chlorotrifluoroethylene, or mixtures thereof, in a percentage by moles in the range 30-90%, preferably 45-65%;
(c) from 0.1 to 30%, preferably from 1 to 15%, by moles with respect to the total amount of (a)+(b), of a hydrogenated monomer of formula:
CH
2
═CH—(CH
2
)
n
—R
1
(I)
wherein R
1
=—OR
2
, —(O)
t
CO(O)
p
R
2
wherein t and p are integers equal to 0 or 1, and R
2
is a hydrogenated radical from 1 to 20 carbon atoms, linear and/or branched, or cycloalkyl, C
1
-C
20
alkyl radical, or R
2
is H. The R
2
radical can optionally contain: heteroatoms preferably Cl, O, N; one or more functional groups preferably selected from OH, COOH, epoxide, ester and ether; and double bonds; n is an integer in the range 0-10. Preferably R
2
is an alkyl radical from 1 to 10 carbon atoms containing one or more hydroxide functional groups and n is an integer in the range 0-5.
The comonomers (c) are for example selected from the following classes:
1) Acrylic monomers of formula:
CH
2
═CH—CO—O—R
2
wherein R
2
has the above mentioned meaning.
Among the monomers which have the formula reported in 1) can be mentioned for example: ethylacrylate, n-butylacrylate, acrylic acid, hydroxyethylacrylate, hydroxypropylacrylate, (hydroxy) ethylhexylacrylate, acryl (N-alkyl) amide wherein alkyl is C
1
-C
5
, etc.
2) Vinylether monomers of formula:
CH
2
═CH—O—R
2
wherein R
2
has the above mentioned meaning.
Among the monomers which have the formula reported in 2) can be mentioned for example: propylvinylether, cyclohexylvinylether, vinyl-4-hydroxybutylether, etc.
3) Vinyl monomers of the carboxylic acid of formula:
CH
2
═CH—O—CO—R
2
wherein R
2
has the above mentioned meaning.
Among the monomers which have the formula reported in 3) can be mentioned for example: vinyl-acetate, vinylpropionate, vinyl-2-ethylhexanoate, etc.
4) Unsaturated carboxylic acids of formula:
CH
2
═CH—(CH
2
)
n
—COOH
wherein n has the above mentioned meaning. Vinylacetic acid, etc. can for example be mentioned.
The preferred class of monomers (c) are acrylic monomers 1), the most preferred is n-butyl acrylate.
The preferred fluorinated monomer (b) is chlorotrifluoroethylene.
The PCTFE percentage in the blends is in the range 1-75% by weight, preferably 5-30% by weight.
The PCTFE is a semicrystalline (co)polymer of chlorotrifluoroethylene (CTFE) containing at least 99% by moles of chlorotrifluoroethylene where the complement to 100% is formed by one or more hydrogenated monomers, preferably acrylic, or fluorinated monomers, preferably selected from (per)fluoroalkylvinylethers, (per)fluorodioxoles. Preferably the PCTFE is the CTFE homopolymer.
PCTFE and PCTFE blends with the copolymers based on ethylene, TFE and/or CTFE modified with hydrogenated monomers, are obtained according to European patent applications No. 01101784.5 and No. 01101785.2 in the name of the Applicant, herein incorporated by reference.
As component I) fluoropolymers in blend with PCTFE are preferred.
The hydrogenated plasticizers used in mixture with the fluoropolymers component I) of the present invention are those of the prior art, which are used in mixture with hydrogenated (co)polymers; their percentage by weight, based on the total weight of the composition of the present invention, is in the range 0.1-10%, preferably 0.5-5%.
Non limitative examples of said plasticizers are the following: 2-ethylhexyldiphenylphosphate, neopentyl glycoldibenzoate, tricresylphosphate, acetyl-tri-n-butyl citrate (Citroflex® A4), tributyl trimellitate, tetrabromophthalic ester, tri-n-hexyl-trimellitate (Morflex®560), ethylene glycol monostearate, acetyl-tri-n-hexyl citrate, di-butoxyethyl adipate (Plasthall®203); the following are preferred: acetyl-tri-n-butyl citrate, tributyl trimellitate, tri-n-hexyl-trimellitate, di-butoxyethyl adipate.
The “fire retardants” component II) of the composition of the invention are inorganic compounds and their percentage by weight is in the range 0.1-35%, preferably 0.5-15% based on the total weight of the composition.
Examples of these components are inorganic phosphates (for example ammonium phosphate), metal oxides (for example aluminum oxide, trihydrate aluminum oxide,
Abusleme Julio A.
Zolotnitsky Mikhail
Ausimont S.p.A.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Hu Henry
Wu David W.
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