Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
lV4~
This invention relates to phosphorùs-containing flame retardants
and to polymer compositions containing these retardants.
~ nited States Patent No. 3,027,349 describes a mixed phosphite-
phosphonate polymeric material produced by isomerizing tris(2-chloroethyl)
phosphite at tcmperatures greater than 180C. e~g. 180-300C. These materials
can be used as flame retardants. These materials have a phosphite structure in
the molecule.
We have now discovered flame retardant mixtures which have excellent
properties. The flame retardant mixtures comprise 1 to 75 weight per cent of
a compound having the structure:
.~ O
,;~ (ClCH2CH20)2 PCH2CH2Cl
. . .
and 99 to 25 weight per cent of a high boiling phosphonate comprising
predominantly a compound having the structure:
,. O O
''~ ClCH2CH201 OCH2CH2P(OCH2CH2Cl)2
CH2cH2cl
Polymers, particularly rigid and flexible urethane foams, generally
contain 2 to 30 weight per cent of the flame retardant mixture.
-` The flame retardant mixtures are produced by the thermal isomeri-
zation of tris(2-chloroethyl)phosphite (TECP). The isomerization is carried
out by slow addition of the phosphite to a product heel at a temperature
below 180 C. (normally about 175C.). The major constituent of the product
~` is about 65 per cent, by Vapor Phase Chromatography CVPC), bis(2-chloroethyl)2-
'~ chloroethyl phosphonate having the structure:
1l
(ClCH2CH20)2 PCH2CH2Cl
,. ~ .
.~,,
10~4854
The remainder is high boiling phosphonate which comprises predomlnantly
a compound having-the structure:
O O
ClCH2CH20PC~2CH2P(CH2CH2C )2
~H2CH2Cl
Evidence for this structure includes the presence of a ma~or peak in
the VPC analysis with a retention time consistent with a structure in the dimer
molecular weight range and the absence of significant amounts of titratable P (III)
phosphorus in the product. This contrasts with the material described in U.S. Patent
3,027,349 which contains a si~nificant amount of phosphite which is titratable
by the standard I2 method. The high boiling phosphonate may also contain small
amounts of trimer and higher phosphonates similar to the above structure.
This mixture about 65 weight per cent monomeric phosphonate
and, after stripping out low boiling by-products at a pressure of 15 - 25 mm
Hg at about 150C., can be used directly as a flame retardant mixture.
This mixture can also be sub~ected to fractional distillation to
separate monomer product from high boiling phosphonate, leaving a high boiling
phosphonate containing 1-2 weight per cent of residual monomer. ~hese fractions
can be blended to produce flame retardant mixtures in accordance with this
invention containing varying proportions of monomer to high boiling phosphonates.
In order to produce the flame retardant mixtures of the present
invention, the 65% monomer - 35Z high boiling phosphonate mixtures can be used
as such or mixtures can be prepared by suitable blending of the monomer and the
high boiling phosphonate to produce the desired mixture in accordance with the
invention. Intermediate mixtures can be prepared by stripping off only part of
the monomer. These mixture will contain from 1 to 75 weight per cent monomer,
preferably from 2 to 65 weight per cent, and from 99 to 25, preferably from 98
to 35 weight per cent, high boiling phosphonate.
The invention will now be described with reference to preferred
embodiments, making reference to the accompanying drawings in which:
-2-
Figure 1 presents a curve showing the correlatlon between the per cent
monomer in the flame retardant mixture and the burning rate for an unaged flexl-ble foam composition;
Fig. 2 presents the same correlation as in Fig. 1 fbr aged ~lexlble
foam compositions;
Fig. 3 presents the correlation between the per cent flame retardants
in flexible foam and the Limiting Oxygen Index (LOI) found and predicted,
EXAMPLES 1-7
Flexible fire-retardant ~rethane foams were formulated as follows:
Table I
~ edients Parts by Welght
T~luene diisocyanatea 42.2
Polyether triolb ~ 100.0
Water 3.2
Sllicone SurfactantC 1.0
Amine Catalystd 0.3
Stannous Octoate 0.3
Foaming Agente 3.0
Flame Retardant Agent 10.0
(a) Allled Chemical, Nacconate 80; (b) Union Carbide LG-56;
- (c) Union Carbide Y-6634; ~d) Houdry Dabco 33-LV; (e) DuPont
R-ll (trade marks)
The flame retardant agent was formulated from the monomeric and hlgh
; bolling phosphonate fractions described above to prepare flame retardants with
the desired mDnomer content. These flame retardants were formulated in flexlbleurethane foams as indlcated abo~e, and tested in ASTM D-1692-68.
--3--
test (T~ble II). The samples with < 90% monomer content
. gave essentially equivalent results and were clearly
superior to the 90% monomer material (Table II and
Figure 1).
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EXAMPLES 8 - 14
Samples of the foams used in Examples 1 - 7
were subjected to thermal aging at 250F. far 24
hours prior to testing in the ASTM D-1692-68 te~t (Table
III). Foam with 65% monomer content flame retardant
exhibited better flame retardancy than foam with 90%
monomer content flame retardant. Samples with <65% monomer
content flame retardant had similar flame retardancy, all
significantly better than foams for~ulated with flame
retardant containing greater amounts of monomer.
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Fig. 1 is based upon the data set forth in Table II
and presents a curve showing the relationship between the
weight per cent monomer in the flame retardant mixture of
monomer and high boiling phosphona.te and the inches burned
of the unaged flexible foam. From the curve, it will be noted
that good ~lame retardancy is obta.ined with a flame reta.rdant
mixture containing as much a.s 75 weight per cent mon~mer.
Fig. 2 is based upon the data set forth in Table III
and presents a curve showing a similar (to Fig. 1) relationship
for the flexible foam a~ter aglng. It will be noted from the
curve tha.t good fla.me retardancy is obtained with a ~lame re-
ta.rdant mixture containing as much as 40 weight per cent mono-
mer. At different loadings or with different ~ormulations the
maximum monomer content that will afford good flame reta.rdancy
will be expected to vary to some extent.
EXAMPLES 15-20
Flexible urethane foams were prepa.red~using a.
~ormulation similar to the formulation in Table I, aga.in
using 10 parts by weight o~ ~lame retarda.nt. The flame
~ 20 retardants used were the 65~ monomer content phospho~a.te
.` product of TCEP rearrangement and the 2~ monomer content
phosphonate produced by removing monomer from the 65
monomer material. Foams conta.ining the 2~ monomeric
phosphonate had significa.ntly better flame reta.rdancy
after heat aging, as measured by Limiting Oxygen Index
; Test, ASTM-D-2863 and by the ASTM D-1692-68 test.
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4t~54
EXAMPLES 21-24
Flexible uretha.ne ~oams were prepared uslng a
formulation similar to tha.t given in Table I, except
that the flame retardant level was varied from 0 to
15 parts by weight. The flame retarda.nt was aga.in
the 65~ monomeric phosphona.te product o~ TCEP re-
arrangement. Flame reta.rdancy was measured by the
LOI Test ASTM D-2863 be~ore and a.fter hea.t aging at
240F. for 24 hours and the weight loss ~n hea.t
aging was measured (Ta.ble V). The loss of ~lame re-
tardancy wa.s clearly less than predicted based on
the weight loss (Ta.ble V a.nd Figure 3).
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~0~54
Fig 3 is based upon the data set forth in Table V
and presents curves showin~ the relationship between the LOI
and weight per cent of 65% monomer flame retardant mixture
initially in flexible urethane. Curve A shows the LOI
actua.lly found for the flexible foam after aging. Curve B
shows the LOI predicted (B) for a f~am ha.ving the net amount
of flame reta.rdant remaining after aging as compared with the
LOI usually experienced with a foam c~ntaining that (net)
amount of fla.me retardant in ~resh foam, corrected by the
loss in flame retardancy experienced with this foam with no
~lame retardant after aging. It will be apparent from c~mparing
the curves that a greater amount of flame retarda.ncy wa5 ex-
: perienced than could be expected or predicted.
EXAMPLES 2~-29
-. 15 Rigid polyurethane foams containing the 65% mono-
meric phosphona.te flame retarda.nt mentioned above exhibit
. surprisingly better flame retardancy than foams formulated
with corresponding amounts`of the simila.r material tris
(2-chloroethyl) phosphate, as measured b~ weight loss
following corner ignition of 2" x 8.5" x l/2" sa.mples.
The samples a.re placed at a 45 a.ngle rela.tive to the
ignition source, an Anderson-Forrester micro burner
(Table VI).
-12-
10~5~
TABLE VIl
Examples 25 26 27 28 29
Flame Retardant2 _ A A B B
PBW flame retardant 0 5 10 5 10
~ Wt. loss
(45 angle test) 78 21 12 76 30
1450 angle ~lame retardancy tests ~or rigid polyuretha.ne
foams
2A - 65% monomeric content phosphonate mentioned above
B - tris (2-chloroethyl) phosphate
. EXAMPLES 30-43
Samples of flexible polyurethane foa.m formulated
with the 65% monomeric phosphonate mentioned above, like-
wise exhibit better flame retardancy and retention than
similar foams formulated with the similar flame retar-
. dent tris (2-chloroethyl) phospha.te (~able VII.).
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-14-
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1~)44~4
In the foregoing Exa~ples 25 throu~h 43, the tris
~2-chloroethyl~ phosphate used has ~ structure similar to
that of the bis (2-chloroethyl~ 2-chloroethyl phosphonate.
Thus, both could ~e expected to behave similarly as flame
retardants. Surprisingly, the phosphonate ~as found to be
more effective.
EXAMPLES 44-53
The 65% monomeric phosp~onate is an effective
flame retardant in a broad range of plastic resins as
measured by the Limiting Oxygen Index ASTM D-2863 (Table VIII).
- 15 -
1049~85~
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-16-
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~5)448~4
The flame retardant mixtures of this invention
are effective at flame retardant c~ncentrations in polymers,
including, by way of non-limiting examples, rigid poly-
urethanes and flexibl.e polyurethanes, polyethylene, tere-
phthalate, polycarboxyamide, polyacrylonitrile, acetate
ra.yon, polystyrene and other styrene polymers (e.g., ABS).
They will a.lso be effective in combinations with polymeric
materials such as cotton, cellulose, paper and silk; cel-
lulose esters and ethers such as cellulose aceta.te butyra.te
and ethyl cellulose; polyvinyl chloride; polymethyl meth-
acryla.te a.nd other acrylates; nylons; polyolefins such as
polyethylene and polypropylene; phenol-aldehyde resins;
alkyd resins, urea. resins, epoxy resins; linear and cross-
linked polyester, and ma.leic anhydride heteropolymers.
; 15 Flame retardant concentrations can vary dependent upon the
polymer used. In genera.l, they will be 2 to 30 per cent,
preferably 4 to 16 per cent, based upon the weight of the
t.otal composition.
The flame reta.rdant mixtures can be incorpora.ted
into the polymer during the polymerization step or by a.dmixing
with the p~lymer prior to or during milling, extrusion, spinning,
foaming, pressing or other conventional opera.tions for forming
or applying the polymeric end-product.
The physical form of the flame reta.rda.nted composition
can va.ry widely. While rigid and flexible polyuretha.ne foams
;~ are of ma.jor interest, fibers, films, coa.tings, sheets, rods,
boards, and the like ca.n be used.
-17-
10~8~
Although the present invention has been described
with preferred embodiments, it is to be understood that
modifications and variations may be res~rted to, without
departing from the spirit and scope of this invention as those
skilled in the art will readily understand. Such modifications
and variations are considered to be within the purview and
scope of the appended claims.
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