SOLUTION EXTRUSION OF POLYPHENYLENE ETHER COMPOSITIONS

EXTRUSION EN SOLUTION DE PRODUITS A BASE D'ETHER POLYPHENYLENIQUE

English Abstract

ABSTRACT OF THE DISCLOSURE
A novel process is disclosed for preparing thermo-
plastic compositions of a polyphenylene ether resin and a
vinyl aromatic resin which is based on solution extrusion,
with simultaneous removal of solvent.

Claims

The embodiments of the invention in which an exclu-
sive property or privilege is claimed are defined as follows:
1. A method of producing a composition of a
polyphenylene ether resin and a vinyl aromatic resin, said
method comprising providing a solution of said polyphenylene
ether and said vinyl aromatic resin in a high boiling solvent,
and thereafter, extruding the solution through a devolatilizing
extruder to remove said high boiling solvent to form a sub-
stantially solvent-free composition.
2. The method of claim 1 wherein the solution
of said polyphenylene ether and said vinyl aromatic resin
is concentrated prior to extrusion.
3. The method of claim 1 wherein said polyphenylene
ether resin is of the formula:
<IMG>
wherein the oxygen ether atom of one unit is connected to the
benzene nucleus of the next adjoining unit, n is a positive
integer and is at least 50, and each Q is a monovalent substi-
tuent selected from the group consisting of hydrogen, halogen,
11

hydrocarbon radicals free of a tertiary alpha carbon, halo-
hydrocarbon radicals having at least two carbon atoms between
the halogen atom and the phenyl nucleus, hydrocarbonoxy
radicals having at least two carbon atoms.
4. The method of claim 1 wherein said vinyl aromatic
resin has at least 25% of its units derived from a monomer of
the formula:
<IMG>
wherein R1 and R2 are selected from the group consisting of
lower alkyl or alkenyl groups of from 1 to 6 carbon atoms and
hydrogen; R3 and R4 are selected from the group consisting of
chloro, bromo, hydrogen and lower alkyl of from 1 to 6 carbon
atoms; R5 and R6 are selected from the group consisting of
hydrogen and lower alkyl and alkenyl groups of from 1 to 6
carbon atoms or R5 and R6 may be concatenated together with
hydrocarbyl groups to form a naphthyl group.
5. The method of claim 1 wherein said composition includes
a reinforcing amount of a reinforcing filler.
12

6. The method of claim 1 wherein said composition
includes a flame retardant agent.
7. The method of claim 5 wherein said composition
includes a flame retardant agent.
8. A method of producing a composition of from 99-1
parts by weight of a polyphenylene ether resin of the formula:
<IMG>
wherein the oxygen ether of one unit is connected to the benzene
nucleus of the next adjoining unit, n is a positive integer and
is at least 50, and each Q is a monovalent substituent selected
from the group consisting of hydrogen, halogen, hydrocarbon
radicals free of a tertiary alpha carbon atom, halohydrocarbon
radicals having at least two carbon atoms between the halogen
atom and the phenyl nucleus, hydrocarbonoxy radicals having
at least two carbon atoms and from 1-99 parts by weight of a
vinyl aromatic resin that has at least 25% of its units derived
from a monomer of the formula:
<IMG>
wherein R1 and R2 are selected from the group consisting of
lower alkyl or alkenyl groups of from 1 to 6 carbon atoms
and hydrogen; R3 and R4 are selected from the group consisting
of chloro, bromo, hydrogen and lower alkyl of from 1 to 6
carbon atoms; R5 and R6 are selected from the group consisting
of hydrogen and lower alkyl and alkenyl groups of from 1 to 6
carbon atoms or R5 and R6 may be concatenated together with
13

hydrocarbyl groups to form a naphthyl group said method
comprising providing a solution of said polyphenylene ether and
said vinyl aromatic resin in a high boiling solvent and there-
after extruding the solution through a devolatilizing extruder
at a temperature of 190-330°C at a reduced pressure of 10-100 mm
of Hg. to remove said high boiling solvent and form a substantially
solvent-free composition.
9. A method as defined in claim 8 wherein 1-80% of
glass fibers are added to the solution prior to extrusion.
10. A method as defined in claim 5 wherein 1-80% of
glass fibers is added prior to extrusion.
11. A method as defined in claim 8 wherein the
polyphenylene ether resin is poly(2,6-dimethyl-1,4-phenylene
ether.
12. A method as defined in claim 9 wherein the
polyphenylene ether resin is poly(2,6-dimethyl-1,4-phenylene
ether.
13. A method of producing a composition of from 99-1
parts by weight of a polyphenylene ether resin of the formula:
<IMG>
wherein the oxygen ether of one unit is connected to the
benzene nucleus of the next adjoining unit, n is a positive
integer and is at least 50, and each Q is a monovalent substituent
selected from the group consisting of hydrogen, halogen, hydro-
carbon radicals free of a tertiary alpha carbon atom, halo-
hydrocarbon radicals having at least two carbon atoms between the
halogen atom and the phenyl nucleus, hydrocarbonoxy radicals
14

Claim 13 continued:
having at least two carbon atoms and from 1-99 parts by weight
of a styrene resin, said method comprising providing a solution
of said polyphenylene ether resin and said styrene resin in a
solvent selected from the group consisting of chlorobenzene
and toluene and thereafter extruding the solution through a
devolatilizing extruder at a temperature of 190-330°C at a
reduced pressure of 10-100 mm of Hg. to remove said solvent
and form a substantially solvent-free composition.

Description

8CH-1835
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The invention relates to a novel process for ~:
preparing thermoplastic compositions o~ a polyphenylene ~ ~:
ether re~in and a vinyl aromati~ resin which employs
solution extrusion.
q~he term "polyphenylene ethar re4in in~ludes -~
. a ~amily of polymers well lcno~ to those skilled in
the art, and they are made by a variety of catalytic and
non-¢atalytic processes from the corresponding phenols
, ~ . .. ..
or reactive derivativ~es thereof. By way o~ illustrationg
t.,.~ 10 certain o~ ~he polyphenylene ethers are disclosed in ~: :
- Hay U S. Patent 3,3063874 da~ed Fe3~raury 28, 1967 and
3,306,875 dated February 28, 1967, and in Stamatvff, ~-
U S patent ~rO. 3,2579357 dated June 21, 1966 and Patent
~: # 3,257,358 dated June 21, 1966. In the Hay patents5, :
, ~
.~ 15 ~he polyphenylene ethers are prepared by an oxidative
coupling reaction comprising passing an oxygen-containing `:
g~s .through a reaction solution of a phenol and a metal - ~:
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8CEI-1835
amine complex catalyst. Other disclosures relating to processes
for preparing polyphenylene ether resins, including graft
copolymers of polyphenylene ethers with styrene type compounds,
. .
are found in Fox, U.S. 3,356,761; Sumitomo, U.K. 1,291,609; ;-
Bussink et al, U.S. 3,337,499; Blanchard et al, U.S.
3,219,626; Laa]cso et al, U.S. 3,342,892; Borman, U.S.
3,344,166; Hori et al, U.S. 3,384,619; Faurote et al, U.S.
3,440,217; and disclosures relating to metal based catalysts
which do not include amines, are known from patents such as
Wieden et al, U.S. 3,442,885 (copper-amidines); Nakashio et al,
U.S. 3,573,257 (metal-alcoholate or -phenolate); Kobayashi et
al, U.S. 3,455,880 (cobalt chelates); and the like. In the
Stamatoff patents, 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. Disclosures
relating to non-catalytic processes, such as oxidation with
lead dioxide, silver oxide, etc., are described in Price et al,
U.S. 3,382,212. Cizek, U.S. 3,383,435 discloses polyphenylene
ether-styrene resin compositions.
The Cizek patent discloses a method o~ preparing styrene
resin compositions by dry blending the compositions and then
melt blending the dry blend in an extruder. This process
requires the preparation of the polyphenylene ether in dry form
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8CH-1835
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free of the solvent system in which it was formed by the
oxidative coupling of a phenolic monomer. Applicant has dis-
covered that if the phenolic monomer is polymerized in a suitable
solvent system, a vinyl aromatic compound may be dissolved in
the reaction solution and that composition may be solvent
extruded to form a dry extrudate in a single step processL
This is highly advantageous as it eliminates the need for a
separate system for the precipitation and drying of the poly~
phenylene ether resin.
Accordingly, it is a principal object of this invention
to provide an improved method of preparing a polyphenylene ether " ~-
resin-vinyl aromatic resin composition.
It is also an object of this invention to provide a
method for preparing a polyphenylene ether resin-vinyl aromatic
resin composition which eliminates the need to separate the poly-
; phenylene ether resin from the solvent in which it is prepared.
U.S. 3,437,638 to Bottenbruck et al discloses a
method for the separation of solvent from a polycarbonate
solution which is based on the extrusion of a mixed solvent
solution of polycarbonate. The polycarbonate solvent extrusion
process was employed only to reduce residual chlorine by means
of the added second solvent. No compositions are directly ~`
formed in the Bottenbruck et al process.
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Description of the Invention - According to the present
inven-tion, there is provided a method of producing a composition
of a polyphenylene ether resin and a vinyl aromatic resin,
said method comprising providing a solution of said polyphenylene
ether in a high boiling solvent, and thereafter, extruding the
solution through a devolatilizing extruder to remove said high
boiling solvent to form a substantially solvent free composi-
tion.
The extrusion step is carried-out i~ a devolatilizi~g
- 10 extruder that is provided with a vacuum venting means which
- facilitates solvent removal during high speed extrusion.
: .
Prior to extrusion, it is preferred to concentrate the polymer
solution by removing a portion of the solvent. The solvent
: . - .
should be capable of dissolving the polyphenylene ether resin
and the vinyl aromatic resin. Suitable high boiling solvents
may be found in the above referenced Hay patents. The preferred
solvents are chlorobenzene and toluene. ~
`~ The preferred extruder for this process is a devolatilizing, ~`
self-cleaning, twin-screw extruder such as the one made by
:- 20 Werner & Pfleiderer Co. of Stuttgart, Germany. Preconcentration
- of the polymer can be effected in an APV type evaporator or a
- wiped film evaporator. The main requirement is good heat
transfer and low skin (surface) temperature to minimize polymer
~`~ degradation and equipment fouling.
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Extrusion temperatures of from 190-330C may be employed
; depending on the solvent and the rate of extrusion. If
vacuum venting is employed, reduced pressures of 10-100 mm
of Hg. may be employed.
The polyphenylene ether resins are preferably of the
type having the repeating structural formula:
Q ` ~
i'- .~ ~
; wherein the oxygen ether atom of one unit is connected to the
i: . .
` benzene nucleus of the next adjoining unit, n is a positive `~
integer and is at least 50, and each Q is a monovalent substi-
tuent selected from the group consisting of hydrogen, halogen,
hydrocarbon radicals free of a tertiary alpha carbon atom,
halohydrocarbon radicals having at least two carbon atoms
~- between the halogen atom and the phenyl nucleus, hydrocarbonoxy
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8C~-1835
radicals and halohydrocarbonoxy radicals having at least two
- carbon atoms.
The vinyl aromatic resins a:re preferably of the type where-
in at least 25~ of the units of ,said vinyl aromatic resin are
,~ of the formula:
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~, 1 2
CR = CHR
! ~ R5~R3
R~--R4
,. .
wherein Rl and R are selected from the group consisting of
~:~ lower alkyl or alkenyl groups of from 1 to 6 carbon atoms and
.,, ~
. hydrogen; R3 and R4 are selected from the group consisting of
chloro, bromoj hydrogen and lower alkyl of from 1 to 6 carbon
~- atoms; R5 and R6 are selected from the group consisting of
' hydrogen and lower alkyl and alkenyl groups of from 1 to 6
. carbons or R5 and R6 may be concatenated together with hydro-
. carbyl groups to form a naphthyl group.
,~.' ,
` Materials that may be copolymerized with the units of the
vinyl aromatic monomer include those having the general formula:
.... .
~ R7 - CH = l (CH2)n 9
` R8
,~;
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8C~I-1835
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wherein R8 and R7 rep.resent a substituent selected from the ~:
group consisting of hydrogen, halogen, an alkyl group of 1-4
carbon atoms, carboalkoxy or R7 and R8 taken together represent
an anhydride linkage (-COOOC -) and Rg is hydrogen, vinyl and
alkyl or alkenyl group having 1-12 carbon atoms, cycloalkyl
having 3 to 6 carbon atoms, carboalkoxy having 2 to 6 carbon
- atoms, alkoxy-alkyl having 2 to 6 carbon atoms, alkylcarboxy
having 2 to 6 carbon atomsr ketoxy halogen, carboxy having l to
~ 6 carbon atoms, cyano, pyridyl and n is a whole number between
0 and 9. -
The general formulas set forth above include by way of
example, homopolymers such as homopolystyrene and monochloro-
polystyrene, the modified polystyrenes, such as rubber-modified,
~- high-impact polystyrene and the styrene containing copolymers,
- such as the styrene acrylonitrile copolymers, styrene butadiene
copolymers, styrene-acrylonitrile-2-alkyl styrene copolymers,
poly-2-methylstyrene, copolymers of ethylvinylbenzene and
divinylbenzene and styrene maleic anhydride copolymers.
. The styrene-maleic anhydride copolymers are described in
,. 20 U.S. 2,971,939; U.S. 3,336,267 and U.S. 2,769,804.
The rubber-modified, high- impact styrene resins are --
preferred and these may be made by well known procedures with
~i: rubbers such as nitrile rubbers, polybutadiene rubber, styrene- .
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8CH-1835
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butadiene rubber, polysulfide rubber, ethylene-propylene
copolymers and EPDM rubbers.
The compositions prepared by the process of this invention
may comprise from 99-1 parts by weight of a polyphenylene
- ether resin and from 1-99 parts by weight of a vinyl aromatic
resin.
i Other additives such as fillers, processing aids, reinforc-
ing fillers, flame retardants and the like may be employed in
the compositions prepared by the method of this invention. -~
. ~
Reinforcing fillers such as 1-80% by weight of filamentous
' glass may be added to the solution prior to extrusion. Agitation
may be used to maintain a homogenous dispersion prior to
extrusion. Flame retardants such as those mentioned in
:li U.S. 3,671,487 dated June 20, 1972 may also be added prior
~ to extrusion.
- Description of the Preferred Embodiment -
~ - ,
EXAMPLE
A solution of 25% w/w of poly(2,6-dimethyl-1,4-phenylene)
ether in chlorobenzene is obtained in accordance with the ~
~- teachings of Hay, U.S. 3,306l876. The catalyst is removed by ;
extraction and the temperature of the solution is raised to ;
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8C~1-1835
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150F. This is combined with an amount of rubber-modified, high-
impact polystyrene (Foster Grant 834) that is equal to the
amount of poly(2~6-dimethyl-1,4-phenylene) ether. This forms
a solution of the two materials with some of the rubber-modified,
high-impact polystyrene slurried in~ The solution is fed to
a devolatilizing extruder (ZDS K-28 Werner Pfleiderer) where
the solvent is removed and a dry extrudate is obtained which
is chopped into molding pellets. The devolatilizing extruder
- is operated at a temperature of 190-310 and under a vacuum `
venting of 25 mm Hg.
By the term "high boiling" solvent as used herein is
meant solvents which boil over about 100C and have a vapor
pressure sufficiently high enough to permit them to be readily `~
stripped off at a temperature which does not cause decomposition
of the polymeric materials.
Useful solvents include toluene, xylene, nitrobenzene, ;~
o-dichlorobenzene, tetrachloroethylene, dichlorobenzene,
t-amylalcohol andthe like.
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8CH-1835
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Obviously other modifications and variations of the present
invention are possible in the light of the above teachings.
It is, therefore, to be understood that changes may be made
in the particular embodiments of the invention described which .
are within the full intended scope of the invention as defined
by the appended claims.
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-- 10 --