Note: Descriptions are shown in the official language in which they were submitted.
2~7
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.. . .. . . ...
SI-LOXANE BLOCK COPOLYMERS
.. . .... _ .
B~CKG~OU~ OF THE ;INVEN~ION
The polyphenylene ether resins are a famlly
vf engineering thermoplastics that are well known to the
polymer art. These polymers may be made by a ~ariety
of catalytic and non-catalytic processe from the corres-
ponding phenols or reactive derivatives thereof. By
way of illustration, certain of the polyphenylene ethers
are disclosed in Hay, U.S. Pat. Nos~ 3,306,874 and
3,306,875 and in Stamatoff, U.S~ Pat. Nos. 3,257,357 and
3,257,358. In the Hay patents, the polyphenylene ethers
are prepared by an oxidative coupling reaction comprising
passing an oxygen-containing gas through a reaction solu
tion of a phenol and a metal-amine complex catalystO
Other disclosures relating to processes for preparing
polyphenylene ether resins, including graft ccpolymexs
of polyphenylene ethers with styrene type compounds,
are found in Fox, ~.S. Pa~. No. 3,356,761, Sumitomo,
IJ.K. Pat. NoO 1,291,609i Bussink et al., U.S. Pat. NosO
3~337,499; Blanchard et al., 3,219,626; Laakso et al.,
3,~42,892, Borman, 3,344,116; Hori et al-.5- 3,384/619;
Faurote et alO, 3,440,217; and disclosuxes relating to
metal based catalysts which do not include amines, are
known from U.S. Pat~ Nos. such as Wieden et al.~ 3,442,885
(copper-amidines); Nakashio et al~, 3,573,257 (metal-
alcoholate or -phenolate); Kobavashi et al., 3,455,880
(cobalt chelates~; and the like. In the S.am~tof~ paten~s,
~,
, =, . . .
.. .. .... . . .... ............. . ...
27
8CN-1926
the polyphenylene ethers are produced by reacting the
corresponding phenolate ion with an initiator, such as
peroxy acid salt, an acid peroxide, a hypohalite, and
the like, in -the presence of a complexing agent. Dis-
closures relating to non-catalytic processes, such as
oxidation with lead dioxide, silver oxide, etc. are
described in U.S. Patent No. 3,382,212, issued
May 7, 1968 to Price et al. U.S. Patent No. 3,383,435,
issued May 14, 1968 to Cizek, discloses polyphenylene
ether-styrene resin compositions.
In the prior art, rubber modified styrene
resins have been admixed with polyphenylene ether resins
to ~orrn compositions that have modi.fied properties.
The Cizek patent, U.S. Patent No. 3,383,435, discloses
rubber-modified styrene resin-polyphenylene ether resin
compositions wherein the rubber component is of the un-
saturated type such as polymers and copolymers of
butadiene. The physical properties of these compositions
are such that it appears that many of the properties
of the styrene resins have been upgraded, while the
moldability of the polyphenylene ethers is improved.
U.S. Patent No. 3,65~,945, issued
April. 25, 1972 to Nakashio et al, discloses that from
0.5 to 15~ by weight o:E an EPDM rubber modified by
grafting with styrene may be used to upgrade the
.impact strength of polyphenylene ether resins. In
U.S. Patent No. 3,9~3,191, issued March 9, 1976 to
Cooper et al it is disclosed that when the highly
unsaturated rubber used in compositions of the type
disclosed by Cizek is replaced with EP~M rubber that
has a low degree of residual unsaturation~ -the thermal
oxidative stability and color stability are improved.
~ ~ u~ 8C~ 6
It is disclosed in ~aaf, U.S. Pat. No.
3,737,47g that molding resins comprised of polyphenylene
ether resins and polysiloxanes are useful. T~ese com-
positions are prepared by m~chanical mixing and, while
S the compositions are useful for many purposes, they .
have low notched Izod impac~ strength.
In Cooper et al., U.S. Patent No. 4,226,761
there are disclosed compositions of a polyphenylene
ether resin and an alkenyl resin that is modiied with
a polysiloxane in the form of small rubber like particles.
It has now been found that a composi~ion of a
polyphenylene ether resin, which is also known as a poly~
phenylene oxide ~PPO) resin, and a block copolymer of
polyphenylene ether and siloxane or a block copolymer of
styrene and siloxane is a ~ery useful ~hermoplastic
molding composition possessing improved impact strength
and resistance to aging with no significant loss in
tensile and elongation properties, or appreciabl~ stress
whitening at the fracture surface of the impact bars.
'
2n It is, therefore, a pximary object of this in
vention to provide improved ccmpositions that axe based
on polyphenylene ethex resin and such block copolymers.
Another object of this invention is to provide
molding compositions and molded aTticles that are based
on a polyphenylene ether resin and the aforemen~ioned
block copolymers that have improved impact strength,
resistance to aginy, and no appreciable stxess whitening
at the fracture surface of the impact bars.
,
~ ~9 5~ ~ 8CN-1926
DESCRIPTION OF THE INVENTION
The above-mentioned advantages and objects
and others will be readily apparen~ ~o those skilled
in the art by the following compositions.
The compositions of this invention are thermo-
plastic compositions which comprise:
(a) a polyphenylene ether resin; and
(b) a block copolymer of polyphen~len~
ether and siloxane or a block co-
polymer of styrene and siloxaneO
The preferred polyphenylene ether homopolymers
and copolymexs are of the formula
"' Q'
_ ~-0-~ _.
: Q" Q n
wherein Q, Ql, Q~ and Q"' axe independently selected
.l5 from the ~roup consistins of hydrogen, hydrocarbon
radicals, halohydrocarbon radicals havi.ng at least two
carbon atoms between the halogen atom and the phenol
nucleus, hyarocarbonoxy radicals and halohydrocarbonoxy
radicals having at least two carbon atoms between the
halogen atoms and the phenol nucleus, and Q', Q" and
Q"' in addition may be halogen with the proviso tha~
Q and Q' are preferably free of a tertiary caxbon atom;
and n represents the total number of monomer residues
and is an integer of at least 50.
.... _ .. _ ., .. ~
~ 5 ~2 7 8CN-1926
Examples of polyphenylene ethers correspondin~,
to the above formula can be found in the above~referenced
patents of Hay and Stamatoff. Especially preferred i5
poly(2,6-dimethyl-1,4-phenylene~ether.
The block .copolymer ~ styrene and siloxane
should have its styrene units derived from an alkenyl
aromatic monomer of the ormula:
CRl=CR2
~`,f
R6
1 2
. wherein R and R are selec~ed from the group consis~ing
of hydrogen and lower alkyl or alkenyl groups of from
- 1 to 6 carbon atoms; R3 and R4 are selected from the
group consisting of chloro, bromo, hydrogen, and lower
alkyl groups of from 1 to 6 carbon atoms; and R5 and
R6 are selected from the group consisting of hydrogen
and lower alkyl and alkenyl groups o from 1 to 6 carbon
atoms or R5 and R6 may be concatenated toge~her with
hydrocarbyl groups to form a naphthyl grollp.
Specific examples of alkenyl aroma~ie monomers
include styrene, bromostyrene, chlorostyrene, alpha-
methylstyrene, para-methyl styrene, vinylxylene, divinyl-
benzeIIe, vinyl slaphthalene, and vinyl-~oluene.
The polyphenyl ether units in the copolymer
are of the formula of the preferred polyphenylene e~hers
described above, the especially preferred units being of
poly(2,6-dimethyl~1,4-phenylene~ether.
.. .... . . .... . . . . . ..
119 5~7 8CN-1926
The block copolymers of polyphenylene ether
and siloxane and of styrene and siloxane can be pre
pared by the procedures set forth in the Examples
bPlow .
Components (a) and (b) are combinable in a
fairly wide range of proportions. Preferably, the
compositions of this invention comprise for every
100 parts by weight of (a) and (b) together, rom
about 75 to about 95 parts by weight of (a) the poly-
ph~nylene ether to about 25 to about 5 parts by weight
of ~b) the siloxane block copolymer~
The compositions of the invention may be
formed by conventional techniques, that is, by dry
mixing or dry ~lending the components to form a pre-
mix, and then passing the premix through an extruder atan ele~ated temperature, for example at about 550FD
to a~out 625F. The extrudate is molded in a 3 oz.
Newbury injection molding machine at temperature of
550F.
DESCRIPTION OF THE PREFERR~D EMBODIMENTS
The following examples are set foxth as
furthex illu~tratlons of the invention and are not
to be construed 2S limitlng the invention thereto.
EXAMPLE .l
A polyphenylene ether-siloxane-polyphenylene
ether block copolymer is prepared as follows
:
Charge 90 grams o~ poly(2,6-dimethyl-1,4-
phenylene ether resin (PPO~-O~o~ r~i~-
:`
.. ..... . . . .. _ . . ......
s~
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950 millileters of benzyl chloride and S0 milliliters
of benzene, heat under nitrogen-at 145-150DC. for
13-14 hours while distilling off benzene, and let
stand overnight. Then add a solu~ion of 21.6 grams
of dimethyl siloxane in 90 ml of benzyl chloride to
the reaction mixture, with stixring, followed by 250 ml
of benzyl chloride. Heat gently until the mixture is
clear. Add further small amounts of benzyl ehloride
as necessary to obtain clarity~ Heat the reaction
mixture at 145-150C. for 10 houxs. Collect the pro-
duct and wash and/or re-slurry to purity.
The product has an intrinsic viscosity of
about OA8 dl/gm in solution in chloroform at 25 C.
EXAMPLE 2
A siloxane-styrene-siloxane block copolymer
is prepared as follows:
(1) A c~talyst solution is prepared from
4.85 ml (0.03 moles) of phenylcyclohexene-l and 0.21
grams of freshly distilled lithium (freshly di.stilled
from Li2Np) in approximately 75 ml of tetrahydrofuran.
allow to cool to room te~perature, e.g., about 25C.
Charge 250 ml of a 50/50 toluene/tetrahydro-
~uran mixture into a clean 1 liter resin kettle~ Add
10 moles ~35 ml) of the above catalyst solution.
Chill with an ice bath. Add 14 ml of styrene to the
kettle. The addition is accompanied by a noticeable
production of heat, but no particular color change.
Stir for 3~ minutes while chilling with an ice bath~
Then add 100 ml of styrene in S ml portions at 5 minute
intervals (should take about 1 1/2 hours total)O Each
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8CN-1925
addition produces a noticeable solution o heat.
After ~he additions are completed, there is obtained
a moderately viscous syrup which i5 very dark red in
color.
Another solution is in ~he meantime prepared
by dissolving 74 g of hexamethyltrisiloxane in 250 ml
of a 50/50 t~trahydrofuran/toluene solvent mixture.
Add 75 ml of this solution to the first (~he red syrup)~
Begin warming to 50-60~C., then after 15 minutes add
another 50 ml of the hexamethyltrisiloxane solution
A small decrease in the viscosity of ~he red syrup
due to the dilution is noted, together with a slight
lightening of the eolor. The mix~ure is heated at
55-60C. for one hour and the rest of the hexa~ethyl-
trisiloxane solution is added. After 2 hours the colorhas diminished to a moderate red. Heating is continued
for another hour (total heating 4 hours) and the mixture
has become yellowish and much more viscous. At this
point 69 ml of a 0.145 M solution of diphenylsiloxydi-
acetate is added during about 5 minutes, the~ heatedat 60~C. with stirring for 3 hours more. Aftex hea~ing,
the mixture is left at room temperature under a nitrogen
blanket for 24-48 hours.
ThP resulting siloxane-styrene-siloxane block
copolymer is precipitated in methanol. After drying,
169.6 g. of a dusty white powder are obtained (theoretical.
180.9 g. incIuding diphenylsiloxydiacetate). The ~ield
is 93 ~%-
The polymer has an intrlnsic viscosity of
about 0.4 dl/~m as ~easured ln toluene at 25C. It containsabout 48 mole ~ of siloxane.
~ ~ 5~ 7 8CN 1926
(2) To a 1 liter resin kettle partially
immersed in a water bath are added 350 ml of te-tra-
hydrofuran and 31 ml of a catalyst solu~ion prepared
as described above. A ~otal of 101 ml o styrene is
set aside. 24 ml of the s~yrene are chilled for 1/2
hour with an ice ba~h and added to the ket~le. A
second portion consisting of 77 ml of styrene is then
~dded gradually during the next hour. The mixture is
chilled for one hour.
In a separate vessel, a solution of 65.5 g
of hexamethylcyclotrisiloxane în 150 ml of tetrahydro-
furan is prepared 2nd degassed. 70 ml of ~his solu-
tion is added to the above mix~ure, which promptly
gells. The rernainder of the hexamethylcyclo~risiloxane
is added, in three separate portions, during the next
hour with the temperature of the bath surroundîng ~he
ket~le being raised to 50C. The resulting mixture is
very stiff, but plastic. Heating is continued for
hours, while mi~.ing with a paddle blade type mixer.
17 ml of a 1.045 M solution of diphenylsiloxydiace~ate
are added and the mixture is hea~ed to 50-55C. and
sti.rred for 4 additional hours.
The resulting siloxane-styrene-siloxane block
copolymer is precipitated in methanol, separated and
dried to produce a dusty white powder. Yield: 146.8 g
(theoretical 170.3 g including diphenylsiloxydiacetate
couplin~ agent) = 86%.
T~e polymer has an intrinsic viscosi~y of
about 0.5 dl/gm as measured in soluti~n in toluene at 25 c
I~ con~ains about 48 mole % of siloxane. The molecular
weigh~ is o~er 100,000.
3~t~
8CN-lg26
EXAMPLES 3 7
The composi~ions and the proper~ies are
summarized in Table I. The parts are by weigh~ in the
PPO/copolymer ra~ios shown.
In the tabie PPO m~ans poly(2,6-dimethyl-
1,4-phenylene) ether which is also ~nown as poly(2,6-
dimethyl-1,4-phenylene) oxide having an intrinsic
viscosity of abou~ 0.48 dl/g measured in chloroform
at 30 C. Copolymer A stands for the polyphenylene-
ether-siloxane-polyphenylene ether block copolymer
described in Example l. Copolymer B stands for the
siloxane-styrene-siloxane block copolym~r described in
Example 2~1) and Copolymer C for tha~ described in
Example ~(2).
The PPO and ~he copolymers in fine powder
form are dry blended and coextruded in a 3/4" ~ayne
extruder at a temperature of 625 F. The extrudate
was molded into standard test pieces in a 3 oz. Newbury
injection molding machine at molding temperatures of
about 525 F. to about 550 F.
In Table I, Example 3 is a control, containing
no block copolymer. It wil.l be seen that the Examples
c.ontaining the block copolymers have an improved notched
Izod impact ~trength with, in general, no significant
lcss ~'n tensile and elongation properties. It was also
observed that nvne of the blends of the Examples gave
any appreciable whitening at the fracture surface of ~he
impaet test bars as is commonly observed for rubber mod-
ified polystyrene~PPO compositions, which suggest that
the mechanism for reinforcement of PPO by the block co-
polymers of ~he ins~ant invention may be differen~ from
~ha~ in a high impae~ pQlystyrene (HIPS).
Unable to recognize this page.
8CN-1926
-12-
The compositions of the invention can also
include other ingredients such as filler pigments,
fire retardants and the like, as, for example, those
disclosed in U.S~ Patent No. 4,336,761, issued
October 7, 1980 to Cooper et al.
The compositions can be molde~ into any
desired shapes, as for example, by injec-tion molding
in, for example, a Newbury molding machine. Thus, the
compositions can be used to make molded parts such as
spur, helical, worm or bevel gears, ratchets, cams
impactedparts and gaskets~
Obviously, other modifications and varlations
of the invention are possible in the light of the above
teachings. It is, thereforP, to be understood -that
changes may be made in the particular embodiments of the
invention described which are within the full in-tended
scope of the invention as defined by the appended claims.
