Note: Descriptions are shown in the official language in which they were submitted.
wo 95/24445 2 l ~ 3 6 ~ ~ r~l~u~
FJ AM~ R~TARn~NT RT'CyCT.~T2 POLY~TER Cm\qposTTToN~q
RAoKt~R~TNr2 OF T~TT~ VFNTInN
This invention relates to new f lame
retardant polyester compositions and a method for
5 producing the polyester compositions. More
particularly, this invention relates to new flame
retardant copolyesters produced from recycled
polyesters and to a method f or producing the polyester
compo9ition5. More particularly this invention
10 relates to new flame retardant copolyesters produced
from recycled polyethylene terPrhth~ 23te and carboxy-
pho8phinic acids, a process for producing the
copolyesters and shaped articles produced from the
copolyesters .
D~('RTPTInN OF TTT~ PRTOR ART
One of the major uses of polyesters is the
production of shaped polyester articles and of woven
and non-woven textiles such as fabrics, fil2 n~A,
staples or yarn and of sheets. In recent years
20 efforts to make textiles less flammable, to improve
the safety characteristics of products such as
apparel, bedding, home fllrn;~h;ngs, aircraft and
automobile interior fabrics and industrial fabrics,
have increased. It is alæo reror,n; ~r2 that the
25 textiles may be blends, particularly blends of natural
fibers, 6uch as cotton, and synthetic fibers, such as
polyesters .
There are various methods known for flame
retarding textiles. U.S. Patent 4,034,141 teaches the
3 0 use of brominated rhn~rhr~ramidates to treat
combustible materials to impart f ire retardant
properties. The combustible materials are fabrics
such as cotton, rayon and paper and synthetic fibers
such as polyesters. The fire retardant composition is
35 applied by treating the fabric with a solution of the
composition, drying the fabric and curing the
composition .
WO 95124445 ~18 ~ PCTIUS95102651
o
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U.S. Patent 3,969,437 teaches the use of a
specif ic class of cyclic phosphorus estera to prepare
a durable, flame retardant textile finish for cotton-
polyester blends. The phosphorus ester used must
contain at least one carbon-bonded primary alcohol
group, and preferably two or more, plus a pentavalent
phosphorus ester group.
Surface treatment to impart flame retardant
characteristics, and even the admixture of flame
retardant compounds into hardenable shaped
compositions, has disadvantages. Surface treatments
may be removed by cleaning and admixed ~ , ~q may
exude or migrate f rom the product . Theref ore,
attempts have been made to ~v~I~ these
disadvantages by chemically building flame retardant
compounds into the polyester.
U. S . Patent 3, 922, 323 teaches a process for
improving the f lame resistance of polyesters,
especially unsaturated polyesters, by chemically
binding and/or A~1m;~;n~ organic ~hnq~hnrus compounds
and, if desired, halogen ~~, ul-ds into the
polyesters. ~Ialogen rnnt~;n;n~ at least bicyclic
~hnqphnn; c esters which are free from hydroxy and
carboxylic groups are used.
U.S. Patent 3,941,752 teaches a flame
retarded, synthetic linear polyester modified with
carboxy-phosphinic acids. The linear polyester' is the
polyrrnrlPnqation product of a dicarboxlyic acid, a
diol and a flame-retarding carboxy-phosphinic acid
monomer which may contain hetero atoms.
As the environment has received greater
attention, the need for a~high value use for recycled
polyester materials has grown. A need remains for
flame retardant recycled polyethylene ter~orhth~l ~te
materials, with properties e~ual to, or better than,
the properties of virgin polyethylene ter~rhth~l ~te,
which will ~';nt~;n their flame retardant properties
WO gs/244~S 2 ~ 8 3 6 S ~ 7~cl
throughout their useful life and for a process to
produce such a polyester.
STll~RY OF T~TF Tt~V~NTION
It is an obj ect o$ this invention to provide
a flame retardant polyester material, a process to
produce the polyester material and shaped articles
produced from the polyester.
It is another object of this invention to
provide a flame retardant copolyester composition,
10 produced from recycled polyester, in which the flame
retardant material is (-~h~ml t-Al 1 y bound within the
polymer structure.
These and other obj ects are met by this
invention which is directed to copolyesters of
15 recycled polyethylene ter~rhthAl ~te and a carboxy-
phosphinic acid monomer which have flame retardant
properties. The copolyester is preferably a
polyethylene dicarboxylate copolyester having from
about 99 . 9~6 to about 90~ by weight of recycled
20 polyethylene ter~rhthAl ate and from about O .19~ to
about 1096 by weight of the carboxy-rh~srhi nl C acid
monomer. The copolyester is produced by placing the
desired amounts of recycled polyethylene terl~rhthAl Ate
and carboxy-phosphinic acid in a nitroge~ f illed
25 reactor in the presence of ethylene glycol and a
catalyst which is preferably based upon antimony such
as, for example, antimony oxide. The reactor is
heated to a temperature within the range of f rom about
2630C. to about 293C. for a period of from about 1
3 0 hour to about 3 hours . A vacuum is applied slowly to
reduce the pressure to a pressure within the range of
f rom about O . 5 to about 1. 0 mm of mercury .
In addition to copolyesters of polyethylene
terephthalate, the invention also includes
35 copolyesters of other polyalkylene dicarboxylates such
as polybutylene ter~rhthAl ate and polyethylene
nArhth;lnAte .
WO 9S124445 2 1 g 3 6 ~ ~ p~
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DE.~RTPTION OF l~TR ~ ) EMR-)T)IMRNTS
The present invention relates to
copolyesters of recycle~d,polyesters having flamè
retardant properties. The copolyesters of this
5 invention have an intrinsic viscosity greater than
about 0.7, and preferably within the range of from
about O . 7 to about 1. 2 and a glass transition
temperature greater than about 65C. The copolyesters
of the preferred recycled polyethylene ter~rhthAl ~t~
10 are preferably a polyethylene dicarboxylate
copolyester having from about 99 . 9~ to about 909~ by
weight recycled polyethylene ter~rhth~l ~te and from
about O .196 to about 1096 by weight of a f lame retarding
carboxy-phosphinic acid monomer having the general
15 formula:
O O
Il
HO - ~ - R - C - OH
;~1
wherein R is a saturated open-chain or cyclic alkylene
radical having f rom one to about 15 carbon atoms,
preferably from 2 to about 10 carbon atoms, or an
25 arylene or aralkylene radical such as, for example,
methyl, ethyl, propyl, isopropyl, pentyl, neopentyl,
hexyl, cyclohexyl, octyl, 2-ethylhexyl, iso-octyl,
decyl, isodecyl, dodecyl, tetradecyl, -C6H,-, -C6H~-CH2-
, and -C6H4-CH2-CH2-, and Rl is an alkyl radical
3 0 having up to about 6 carbon atoms, an aryl radical or
an alkaryl radical wherein the alkyl substituent has
f rom 1 to about 6 carbon atoms such as, f or
example, methyl, ethyl and n- and i-propyl . The
carboxy-phosphinic acid is preferably 2-carboxyethyl
35 (phenyl) phosphinic acid, 2-carboxyethyl (methyl)
phosphinic acid, the cyclic anhydride of
2-uclrbu~Ly~:thyl (phenyl)phosphinic acid or the cyclic
anhydride of 2 - carboxyethyl (methyl ) rh~rh i n i c acid .
WO 9S/2444S ~ ~ 8 3 ~ PCTlUSgSI02651
--5--
Polymerization of 90g6 by weight recycled
polyethylene ter.orhth~l ~te and 109~ by weight 2-
carboxyethyl (phenyl)pho8phinic acid produced a flame
retardant polyester having an intrinsic viscosity of
5 about 0 . 70 . The polyester, however, had a slight drop
in the glass transition temperature, the melting point
and the crystallinity when compared to virgin
polyethylene terPrhth~l ~te, but the color of the
polyester was improved.
Recycling polyethylene ter~rhth~l ~te
produces a polyester which has a lower molecular
weight than virgin polyethylene ter~rhth~l ~te. The
inclusion of the rhnsph;n;c acid moiety in the process
of this invention promotes chain bonding to produce
15 longer carbon chains and, thus, higher molecular
weights . The; nrl~Rl nn of the phosphinic acid moiety
is a complex process in which the intrinsic visc06ity
of the process fluid drops originally from the
viscosity of the polyethylene ter,orhth~l ~t~ to as low
20 as about 0.25 before it begins to rise and the
intrinsic viscosity of the copolyester may reach as
hiyh as about 1. 2 if the process is allowed to go to
completion .
The preferred acid, 2-carboxyethyl (phenyl)
25 phosphinic acid, may be prepared in accordance with
the t~2nh;n~ in U.S. Patent 4, 081,463 . The
2 -carboxyethyl (phenyl ) rhnsrh; n; C acid is prepared in
two stages by first reacting dichloro(phenyl)rhnsph;n~
with acrylic acid employed at a molar excess of 25
30 to 459~ to form a mixture of three int~L, ';~t"c, 3-
( chlorophenylphosphinyl ) propionyl chloride, the
cyclic anhydride of 2-~:cLLLu~y~thyl (phenyl) phosphinic
acid and the mixed anhydride of acrylic acid with 3-
chlorocarbonylethyl (phenyl)phosphinic acid. The
35 second stage of the process is the hydrolysis of the
of the mixture of the three ; nt~ t~R to obtain
the desired product, 2-~ b-~yc:thyl(phenyl)rhnsrh;n;c
acid .
WO 95/24441i ~ 1 ~ 3 ~ fi 2 PCT/lJS9!;/026~i1
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The f lame retardant copolyesters of recycled
polyethylene ter~rhth~l ~te are preferably polyethylene
dicarboxylate copcl'yesters having from about 99 . 996 to
90% by weight recycled polyethylene terPrhth~l ~te and
from about 0.196 to about 10% of the flame retarding 2-
carboxyethyl (phenyl)phosphinic acid, or the cyclic
anhydride thereof. ~ i
The desired polyester of this invention may
be produced by the polymerization of from about~ 99.996
to about 90~6 by weight recycled polyethylene
ter~rhth~l ~te and from about O .19~ to about 1096 by
weight of 2-uc~Lbu~Ly~thyl(phenyl)rhn~rh;n;c acid. The
expected decrease in reactivity during the
polymerization reaction, resulting from the ~ l;t;nn
of the phosphinic acid rather than another carbonyl
acid group, was not observed. The high molecular
weight of the product polyester indicated that the
phosphinic acid group was highly reactive and the end-
group analysis did not show terminal rhnsph;n;c~ acid
groups in a high proportion. Further, the addition of
E~hn8rhnrug ,~ ~C usually creates additional
observable color in the product. Surprisingly, the
addition of the carboxy-phnsph;n;c acid in this
invention allowed the use of higher amounts of
catalyst and still had less color in the product than
polyesters produced without the included acid.
The copolyesters were produced by placing
the desired amounts of recycled polyethylene
ter~rhth~l~te and 2-carboxyethyl(phenyl)rhnsph; jn;c
3 0 acid in a nitrogen f illed reactor in the presence of
ethylene glycol and a catalyst which is pref erably
antimony oxide. The reactor was heated to a
temperature within a range of from about 250C. to
about 293C., preferably within a range of from about
263C. to about 293C., for a period of from about 1
hour to about 3 hours. A vacuum was applied slowly to
reduce the pressure to a pressure of from about 0 . 5 to
about 1.0 mm of mercury. The reaction rnnt;nllPd at
wo gs/24445 ~ 1 8 3 6 6 ~ F~ IlU . ;A Sl
those conditions for an additional 45 minutes before
the heat and vacuum were removed.
Ethylene glycol was used in the description
of the process and it is the preferred diol. However,
5 other aliphatic diols such as, for example, iql irhi~ti c
diols having from 3 to about 7 carbon atoms, may also
be used.
The carboxy-~hnsrh;n;c acid and its cyclic
anhydride are not volatile under the process
conditions for production of the polyesters so they
can be incorporated in the polyester by inclusion in
the ~nn~i~nRatiOn reaction. When incorporated into the
molecule during the cnnfi~nci~t;nn reaction the
~hngrhr~ru6 rnnti~;n;n~ structural unit is randomly
distributed in the linear polyester product.
The polyesters of this invention may be made
into shaped articles . They may be spun into f; 1 i t c
and f ibers using well known processes and the standard
additional tr~ c. The polyesters may also be
extruded into sheets or formed into shaped articles
which may be solid or hollow by press molding,
injection molding and extrusion. All of these shaped
articles (fibers, sheets and other shapes) are also an
object of this invention.
The fibers and f;l; c have very good and
permanent flame retardant and self-extinguishing
properties. Since they have a good degree of
whiteness, they have very good dyeing properties for
disperse dyestuf f s and their receptivity includes acid
3 o dyestuf f s in color shades of average to deep
intensity. The tensile gtrength of the f;li tc and
f ibers, second order transition temperature and
melting point apprn~r; r -t~l y correspond to the values
for polyesters which do not contain the flame
retardant carboxy-~hncrh;nic acid. The fibers and
f;l: tc are generally usefu- for appl;ci~t;nnc where
readily ignitable textiles cannot be tolerated and it
is possible to use these fibers in c ' ;ni~t;on with
Wo 95l2444s 2 ~ S ~ PCTiUS95/0265
--8--
natural fibers, such as cotton, and other synthetic
f ibers .
Sheets and shaped articles produced f rom the
flame retardant polyester are generally used in
5 locations where it is desired to reduce the possible
serious risks if ignition and a fire occur. If; the
transparency of the shaped articles is not of concern,
their solidity and flame retarding properties can be
~nhAnr-~r1 by the inclusion of inorganic fiber materials
10 such as, for example, glass and quartz fibers and
carbon in the usual quantities, in the polyester
before molding.
This invention will be ~rlA; n~d in detail
in accordance with the examples below, which are for
15 illustrative purposes only and shall not limit the
present invention.
El~7~MPl.~ 1
After the label was removed, a polyethylene
ter~rhthAl Ate bottle, such as those which contain soft
20 drinks, was washed with detergent and water, cut into
pieces and dried at a temperature of about 60C. for 7
hours in a vacuum oven. A mixture of 18 grams of
recycled bottle polyethylene ter~rhthAl Ate, 2 grams of
2-carboxyethyl(phenyl)rhn~h;n;c acid, 3.2 grams of
25 ethylene glycol and 0.02 grams of Ant; y oxide was
placed within a 50 milliliter flask with a stainless
steel stirrer . The f lask had a nitrogen inlet and
outlet and a provision for pulling a vacuum. The
flask was evacuated and filled with nitrogen 3 times
30 at room temperature and then a continuous, slow flow
of nitrogen was m~;ntA;n~tl through the flask. The
flask was placed in a salt bath which had been
preheated to about 250C. The temperature of the salt
bath was raised from 250C. to about 285C over a
35 period of about 1. 5 hours and ethylene glycol was
distilled off. The pressure was then reduced to 150
millitorr over a period of about 1 hour. The pressure
in the flask was further reduced to about 50 millitorr
21~6~2
Wo 95/~4445 ! _ . r~ u",~
over a period of about 3 0 minutes and the reaction was
continued at these conditions for an additional 45
minutes at which time the heat and vacuum were
removed. The resulting copolymer had an intrinsic
5 viscosity of 0.85 at a cr~n~Pnt~ation of 0.5
grams/deciliter in a solution of 60~ phenol/40~
tetrachloroethane at 25C. The glass transition
temperature was determined to be 69C. by differential
scanning calorimeter.
T~MPLT~ 2
The reaction of Example 1 was modified. In
this reaction, 19 grams of recycled bottle
polyethylene ter~rhthAl Ate, 1 gram of 2-
carboxyethyl (phenyl ) ~h- 8rh; n; c acid and 1. 6 grams of
15 ethylene glycol were reacted in the presence of o . 004
grams of antimony oxide. The conditions of the
reaction were as set f orth in ~xamplé 1 above . The
reEulting copolymer had an intrinsic viscosity of O . 83
at a c~ln~ntration of 0.5 grams/deciliter in a
solution of 609~ phenol/40~ tetrachloroethane at 25C.
The glass transition temperature was determined to be
6 9 . 8 C . by dif f erential scanning calorimeter .
E~PT.~ 3
In this reaction, 19.4 grams of recycled
bottle polyethylene ter~rhthAl Ate, O . 6 grams of 2-
carboxyethyl (phenyl)phosphinic acid and O .41 grams of
ethylene glycol were reacted in the presence of o . 004
grams of antimony oxide. The conditions of the
reaction were as set forth in Example 1 above. The
3 0 resulting copolymer had an intrinsic viscosity of O . 93
at a cr~n~ontration of O . 5 grams/deciliter in a
solution of 60~ phenol/40~ tetrachloroethane at 25C.
The glass transition temperature was ~l~t~rrn; n/~d to be
6 9 . 5 0 C . by di f f erent i al s canning cal orimet er .
3 5 The polyesters produced in Examples 1 and 2
were tested f or their f lame retarding properties . The
limiting oxygen index (LOI) was measured to be:
WO 95/24445 ~ '~ 8 3 6 6 ~ PCTIUS95/02651
--10 -
23.4 for recycled polyethylene ter-~rhth~l~te
without additives;
26 . 9 for the flame retardant polyethylene
ter~phth~l ~te copolymer produced in
Example 1; and
25.4 for the flame retardant polyethylene
ter~rhth~l ~te copolymer produced in
Example 2 .
These numbers are relative numbers which ~how the
; _ uv. t in the flame retardant properties provided
by the inclusion of the carboxy-rhnsrh; n; C acid moiety
in the polyethylene ter~rhth~l ~te copolymer. The
numbers are not absolute numbers as the test was not
performed in accordance with ASTM standard procedures.
A strand of each material was tested instead of the
molded tensile bars required by the ASTM procedures.
Conforming to the ASTM re~auirements might change the
numbers shown above; however, it is believed that the
results of such a test would still indicate a similar
; ,_uvl ~ in the flame retardant properties.
While certain preferred ~ R of the
invention have been illustrated and described herein,
it is to be understood that the invention is not
limited thereby and that the invention may be ~
variously practiced within the scope of the following
claims .
