Note: Descriptions are shown in the official language in which they were submitted.
UNITED STATES PATENT APPLICATION
OF: ROBERT JAY AXELROD
FOR: POLYPHENYLENE ETHER ROSINS AND
COMPOSITIONS ~3AT STABILXZED WITH
TRINEOPENTYLENE DIPHOSPHITE
BACKGROUND OF THE INVENTION
The term "polyphenylene ether resin" is well
known as defining class of thermoplastic materials
which possess outstanding physical properties, including
hvdrolytic stability, dimensional stability and excellent
dielectric characteristics. Methods of preparation are
known in the art and described in the patent literature,
e.g., Hay, U.S. Pat.Nos. 3,306,874, and 3,306~875 and
Stamatoff, U.S. Pat. Nos. 3,257,357 and 3,257,358. Other
patents which show the preparation of polyphenylene ether
resins include Bennett and Cooper, U.S. Pat. Nos. 3,369,656
and 3,838,102, as well as Cooper and Bennett, U.S. Pat.
Nos. 3,642,699, 3,661,849 and 3,733,299.
A shortcoming of such thermoplastic materials
is that they are thermally unstable at elevated temperatures
considerably above room temperature, and even at lower
temperatures upon prolonged exposure. As a result, the
polymer can undergo oxidation and degradation when
extruded or molded, as indicated by a tell-tale yellowish
tinge. This imparts an unsightly appearance to the
extruded or molded article and can adversely affect
mechanical properties as well.
It is known that the thermal oxidative stability
o polyphenylene ether resins can be improved by including
I.
8CN-3246
-- 2
certain stabilizers with the resin. One such stabilizer
is diphenyl decyl phosphite. See also U.S. Patent Number
2,952,701 to McConnell et al dated September 13, 1960.
A continulng need exis-ts for ways of improving the
thermal oxidative stability of polyphenylene ether resins
and compositions containing such resins.
I T~ODUCTION TO _HE INVENTION
The discovery has now been made that trineopentylene
diphosphite (hereinafter also referred to as "TNP"), is a
more effective thermal oxidative stabilizer for poly-
phenylene ether resins and compositions,on a
weight for weight basis, than diphenyl decyl phosphite
(hereinafter also ''DPDP'I).
Trineopentylene diphosphite is also sometimes referred
to as 2,2-dimethyl-1,3-propanediol bis (2,2-dimethyl-1,
3-propanediol cyclic phosphite).
DESCRIPTION OF THE INVEMTION
In greater de-tail, the polyphenylene ethers which are
preferred for use in this invention are homopolymers and
copolymers having the formula:
Q"' Q'
j O -
L _ .
n
wherein Q, Q', Q" and Q"', are independently selected from
the group consisting of hydrogen, hydrocarbon radicals,
halohydrocarbon radicals having at least two carbon atoms
8CN-3246
-- 3 --
between the halogen atom and the phenol nucleus, hydro-
carbonoxy radicals and halohydrocarbonoxy radicals having
at least two carbon atoms between the halogen atoms and
the phenol nucleus, and Q', and Q" and Q"' in addition may
be halogen with the proviso that Q and Q' are preferably
free of a tertiary carbon atom; and n represents the total
number of monomer residues and is an integer of at least 50.
Especially preferred is poly (2,6-dimethyl-1,4-
phenylene) ether.
The compositions of the invention can also comprise
polyphenylene ether resins in admixture with alkenyl
aromatic resins as defined by Cizek, U.S. 3,383,435 dated
May 14, 1968,and other thermoplastic elastomers convention-
ally used as auxiliary or modifying resins. These are
employed to lmprove the impact resistance of articles
molded from the mixtures.
As is described in the Cizek U.S. Patent, modifiers
such as butadiene may be incorporated into the alkenyl
aromatic resins to improve the properties of resultant
compositions. Other such modifiers are also known.
These include block and hydrogenated block copolymers
such as are described in U.S. Patent No. 3,660,531 of
Lauchlan et al dated May 2, 1972 or U.S. Patent No.4,167,507
to Haaf dated September 11, 1979. Similarly, graftmodified
polymers are described in U.S. Patent Nos. 3,943,191
dated March 9, 1976, 3,959,211 dated May 25, 1976, 3,974,235
dated August 10, 1976, 4,101,503, 4,101,504, 4,101,505
dated July 18, 1978 and 4,102,850 dated July 25, 1978
all to Glen D. Cooper et al. All of these modified
polyalkenyl aromatic resins are also within the scope of
the present invention.
Specific examples of alkenyl aromatic monomers
include styrene, chlorostyrene, alpha-methylstyrene, vinyl
xylene, divinylbenzene and vinyl naphthalene. Styrene is
particularly preferred.
~2~ 2
8CN-3246
-- 4
The term "styrene resin" as used broadly throughout
this disclosure includes, by way of example, homopolymers
such as polystyrene and polychlorostyrene, as well as
polystyrenes which have been modified by natural or synthetic
rubber, e.g., polybutadiene, polyisoprene, butyl rubber,
EPDM rubber, ethylene propylene copolymers, natural rubber,
polysulfide rubbers, polyurethane rubbers, epichlorohydrin,
and the like; styrene containing copolymers such as the
styrene-acrylonitrile copolymers (SANS styrene-butadiene
copolymers, styrene-maleic anhydride copolymers, styrene-
acrylonitrile-bu-tadiene terpolymers (ABS), poly-alpha-
methylstyrene, copolymers of ethylvinylbenzene and divinyl~
benzene, and the llke; block copolymers of the A-B-A and
A-B type type wherein A is polystyrene and B is an elasto-
meric diene, e.g., polybutadiene, radial -teleblock co-
polymers of s-tyrene and a conjugated diene, acrylic resin
modified sty:renebutadiene resins and the like, and blends
of homopolystyrene and copolymers of the aforementioned
types.
The polyphenylene ether and modifying resin, e.g.,
polyalkenyl aromatic resin, may be present in virtually
any proportion in the present blends. For optimum
physical properties in the blend, however, they are
preferably in a weight ratio of from about 4:1 to 1:2,
respectively.
The trineopentylene diphosphite stabilizer is
normally present in an amount of at least about 0.5 part
per 100 parts of resin to be effective in conferring
the desired thermal oxidative stability. For optimum
results, amounts in the range between 0.1 and 2.0 parts
based on 100 parts of resin are employed.
The molding compositions can also contain one or more
of the supplemen-tary non-resinous agents which have
heretofore been customarily present in polyphenylene ether
resin molding compositions to improve certain other physlcal
and chemical properties of the moldings. These agents include
L2~2
8CN-3246
-- 5
flame retardants, plasticizers, strengthening fibers (for
example, glass fibers and graphite whiskers), mineral
fillers, abrasion resistant components, dyes, and pigments.
Many of such agents are disclosed in said U.S. Patent No.
4,172,929 to Cooper et al dated October 30, 1979.
The supplementary non-resinous agents are present in
total amount between about l and 50%, so as to provide
their customary benefits.
The manner in which the present compositions are
prepared is not critical. In one procedure, a blend premix
is formed by tumbling the ingredients. The blend premix
is passed through an axtruder at an elevated temperature,
e.g., from about 450 to about 600F., dependent on the
needs of the particular composition. The extruder is
cooled and chopped into pellets and the pellets are molded
into any desired shape.
The following examples are given by way of
illustration only alld are not intended as a limitation
on the scope of this invention. Unless otherwise specified
herein, all proportions are provided on a weight basis.
EXAMPLE 1
A base thermoplastic molding composition was prepared
by tumbling 55 parts of poly(2,6-dimethyl-1,4-phenylene
etherl resin (PPO, General Electric Co.), 45 parts of a
rubber modified high impact polystyrene (Foster Grant's
FG 834, containing about 9~ polybutadiene), 3.5 parts of
tri(isopropylphenyl) phosphate flame retardant/plasticizer
(FMC's Kronit~x 50~, 3 parts of titanium dioxide filler,
1,5 part of polyethylene, 0.15 parts of zinc sulfide and
0.15 part of zinc oxide. Three samples were set aside.
To one sample was added 1.0 part (based on 100 parts of
total resin) of diphenyl decyl phosphite (DPDP), in
accordance with the prior art. To a second sample was
added 0.5 parts of 2,2-dimethyl-1,3-propanediol bis(2,2-
dimethyl-1,3-propanediol cyclic phosphite) (TNP), in
accordance with the invention. To a third sample three
8CN-32~6
-- 6
was added 1.0 part of RNP, also according to the invention.
The resultant sample compositions were separately
passed through an extruder at about 550F. he extrudates
were chopped into pellets and molded at an injection
temperature of about 525F. and a mold temperature of
about 180F. to product sample articles.
The molded articles were tested for their comparative
physical properties, the results of which are reported
in Table I.
In the Table, the abbrevations designate the following:
WI Whiteness index
YI = Yellowness index
DTUI, = Distortion Temp Under Load (E'.)
MV = Melt viscosity (1500 sec ,282 C.)
UL 9~ = Avg. flame out time (sec) 62 mil
Gard = Gardner impact (in.-lbs.)
Izod = Notched Izod impact (ft.lbs./in.n.)
C.F. = injection molded channel flow (in.)
,
,,
- 7 - 8CN 3246
. us In
.
O
O O
N
H I) ('I (I
o o Ir
LO ED
r-l l
O
or I oo o
a
or
O O O
o o o
or Lr) or
H H ¦ 00 (I
.
ED O ED
. l
H
. ) I` or
^l
o In O
I_ O
a)
N I)
.
a
.~ Pi
,1
Z Z
En En
Us X
Z O
a)
f
o
Us O
~2~2~
- 8 - 8CN 324
EXAMPLE 2
The procedure of the previous example was
repeated to prepare three additional molded samples
which differ from those of the previous example only
in that they contain 12 parts (per lOO parts or resin)
of titanium dioxide and the stabilizer concentrations
noted below. The actual test resul-ts are set forth in
Table II, with abbreviations as explained above.
-- 9 - 8CN 3246
o
o
N I
H
O Ll~
on
--
I
or
or o
1~7
. O O O
O O O
.
~`J N I
HE Ir) 'r
Ha
En H 00
H r` O 1--
. l
O O O
I_ f
So
N
~, Pi a a a)
I, Z Pi
.~ En .
Us
. o
o
Z; 'so
aJ *
o
Us
- 10 - 8CN-32~6
The foregoing results show that compositions
in accordance with the invention, containing TNP, exhibit
greater thermal oxidative stability than the comparison
compositions containing DPDP on an equivalen-t molar
phosphorus basis, as indicated by the lower yellowness
index and higher whiteness index after heat aging. This
effect is more pronounced at lower levels of titanium
dioxide. In addition, it is seen tha-t with use of TNP
there is an increase in the ability of the compositions
to withstand higher temperatures without deforming, as
indicated by the higher DTUL.
Obviously o-ther modifications and variations
of the present invention are possible in light o-f the
above teachings. For instance, ins-tead of poly(2,6-
dimethyl-1,4-phenylene) ether, there can be used a
copolymer such as poly(2,6-dimethyl-co-2,3,6-trimethyl-
1,4-phenylene) ether. The compositions can also include
other ingredients such as other impac-t modifiers, drip
retardants, reinforcements and/or fillers, antioxidants,
coloring agents, pigments. It is, therefore, to be
understood that changes may be made in the particular
embodiments of the inven-tion described which are within
the full intended scope of the invention as defined by the
appended claims.
