Note: Descriptions are shown in the official language in which they were submitted.
1.7~38~3
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This invention relates to a polyphenylene ether
resin composition having improved heat stability,
Polyphenylene ethers are known resins which
are disclosed, for example~ in U. S. Patents Nos, 3306874,
3306875, ~257357, 3257358 and 4011200 and Japanese Laid-
Open Patent Publication No. 126800/1975, Since poly-
phenylene ethers having a molecular weight above a certain
limit have a high softening point, they are useful in
applications which require heat stability. In formulat-
ing a polyphenylene ether into resin compositions, however,its high so~tenin~ point makes it necessary to use higher
kneading and extruding temperatures than in ~he case of
other versatile resins~ and high temperatures are also
required in molding the resin compositions. Moreover,
molded articles of the polypheny]ene ether resin composi-
tions are frequently used at relatively high temperatures
over long periods of time in contrast to those from
versatile resins~
Because polyphenylene ethers are relatively
unstable to heat as is well known, they undergo degrada-
tion during extrusion and molding at high temperatures,
and result in polyphenylene ether resin compositions and
molded articles having degraded properties and/or dis-
coloration. These deleterious effects limit widespread
utili7ation of polyphenylene ether resin compositions,
and it has been desired to remedy these defects, particu-
larly to improve their heat stability at high temperatures.
Various methods have alr~ady been proposed for
the stabilization of resin compositions containing
- :.
,:
.;
~ 8
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polyphenylene ethersO These methods are classified
lnto a group involvlng capping the hydroxyl grcups
present at the terminals of the polyphenylene ether
molecule by acylation, etcO 9 and a group comprising
adding various stabilizers to polyphenylene ethers.
Known stab~lizers used in the latter group
include, for example, benzoates (U. S. Patent No. 37~79~875),
hexa-alkylphosphoric triamides or combinations thereo~
with other compounds ~U. S. Patents Nos. 3414536, 3420792,
3429850, 3465062, 3472814, 3483271, 3792121 and 3816562),
octa-alkylpyrophosphoramides or combinations thereof with
other compounds ~U. ~. Patent No. 3,450,670), amines
(U. S. Patents Nos, 3,563,934 and 3,956,423), pho~phites
or hydrazines (U. ~. Patent Mo. 3,639,334), alkanolamines
(U. S. Patent No. 3,761,541), arylphosphonic amides
(U. S. Patent No. 3,792,120), sterically hindered phenols
having a triazine or isocyanuric ring (U. S, Patent No.
4,154,719), sub~tituted dicarboxylic acid dihydrazides
(U. S. Patent No, 3,954,904), high-molecular-weight
phosphites or combinations thereof with other compounds
(U. S. Patent No. 3,952,072), amides (Japanese Patent
Public~tion No. 29748/1969), metal dithiocarbamates
(Japanese Patent Publications Nos. 19395/1970 ~nd
8352/1970)~ carboxylic acid anhydrides (Japanese Patent
Publ~cation No. 29,750ll969), phosphites (Japanese
Patent Publication NOr 29,751/1969), sterically hindered
phenols or combinations thereof with other compounds
(Japanese Patent Publications Mos. 43473/1971, 42029/1971,
42030~1971, 42031/1971, 42032/1971 and 4Z033/1971),
- l 1783~
sterically hindered phenols having one amide linkage in
the molecule (Japanese Patent Publication Mo, 24782/1971),
sterically hindered phenols having one ester linkage in
the molecule (Japanese Patent Publication No, 38623/1973),
high-molecular-weight phosphites (Japanese Laid-Open
Patent Publications Nos. 23846/1974, 31755/1974 and
40476/1975), and combinations o~ phosphorous acid amides
and boron compounds (Japanese Laid-Open Patent Publication
No. 129750/1974).
None of these numerous stabilizers previously
proposed have been conductive to the provision of polypheny-
lene ether resin compositions having fully satisfactory
heat stability, particularly at high temperatures> in
practical applications~
It is an object of this inven-tion therefore to
improve the heat stability of a polyphenylene ether resin
composition~
Another object of this invention is to provide a
polyp~enylene ether resin composition having excellent
heat stability at high temperatures.
Still another obJect of this invention is to
provide a polyphenylene ether resin composition showing
inhibited degradation against a long heat history at high
temperatures, which can withstand high temperatures
during kneading, extrusion and molding and give molded
articles having excellent heat stability in long~term
use at high temperatures.
Other objects and advantages of this invention
will become apparent from the following description.
~ .
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I ~ 783
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In accordance with this invention, the objects
and advantages of this invention are achieved by a poly-
phenylene ether resin composition having improved heat
stability9 said composition comprising a polyphenylene
ether resin matrix and dispersed therein, a phosphonous
acid or its ester represented by the following ~ormula (I)
~ OR2
Rl - P \ (I)
OR3
~herein Rl represents an alkyl group, an aryl group which
may be substituted by an alkyl group, or an aralkyl group
which may be substituted by an alkyl group, R2 and R3 are
identical or different and each represents a hydrogen
atom, an alkyl group, an aryl group which may be substituted
by an alkyl group, or an aralkyl group which may be substi-
tuted by an alkyl group.
According to this invention, there is preferably
provided a polyphenylene ether resin composition having
improved heat stability~ comprising a polyphenylene ether
resin matrix and dispersed therein, both the aforesaid
phosphonous acid or its ester and a sterically hindered
phenol.
According to an espeoially preferred aspect of
this invention, there is provided a polyphenylene ether
resin composition having improved heat stability, compris-
ing a polyphenylene ether resin matrix and dispersed
therein, an organic monophosphite or an organic polyphosphite
as well as the aforesaid phosphonous acid or its ester and
-` I 17~8~
~he aforesaid sterically hindered phenol.
The polyphenylene ether resin forming the resin
matrix in the composition of this invention can be a
polyphenylene ether homopolymer or copolymer obtained by
polycondensing at least one mononuclear phenol o~ the
formula
OM
6 ~ ~ -4 (II)
~ R5
wherein R4, R5 and R69 independently from each
other, represent a hydrogen atom or an alkyl
group having 1 to 3 carbon atoms~ provided
that at least one of R4 and R6 is an alkyl
group having 1 to 3 carbon atoms,
or a grafted polyphenylene ether ob-tained by graft-
polymerizing such a polyphenylene ether with a vinyl
aromatic compound~
Methods for producing these polyphenylene ethers
are w`ell known E~ se.
~xamples of the mononuclear phenols of general
formula (II) include 2,6-dimethylphenol, 2,6-diethylphenol,
2,6-dipropylpheno~, 2-methyl-6-ethylphenol, 2-methyl_6-
propylphenol, 2-ethyl-6-propylphenol, m-cresol, 2,3-
dimethylphenol, 2 9 3-diethylphenol, 2~3-dipropylphenol~
2-methyl-3-ethylphenol, 2-methyl-3-propylphenol~ 2-ethyl-
3-methylphenol, 2-ethyl-3-propylphenol, 2-propyl-3-
methylphenol, 2-propyl-3-ethylphenol, 2,3,6-trimethylphenol,
2,3,6-triethylphenol, 2,3,6-tripropylphenol 9 2 9 6-dimethyl-
3-ethylphenol, and 2,6-dimethyl-3~propylphenol.
-- ,
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l l7s3~a
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Polyphenylene ethers derived from these mono-
nuclear phenols, therefore, include homopol~Jmers such as
poly(296-dimethyl-1,4-phenylene)ether, poly(2,6-diethyl-
1,4-phenylene)ether, poly(2,6-dipropyl-1,4-phenylene)
ether, poly(2-methyl-6-e-thyl-1,4-phenylene)ether, poly(2-
methyl-6-propyl-1,4-phenylene)ether, and poly(2-ethyl-6-
propyl-1,4-phenylene)ether; and copolymers such as a
2,6-dimethylphenol/2,~,6-trimethylphenol copolymer (which
denotes a polyphenylene ether copolymer derived ~rom
2~6-dimethyl phenol and 2,3,6-trimethyl phenol, and in the
following description polyphenylene ether copolymers
are represented in the same manner), a 2,6-dimethylphenol/
2,3,6-triethylphenol oopolymer, a 2,6-diethylphenol/2,3,6-
trimethylphenol copolymer and a 2,6-dipropylphenol/2,3,6-
trimethylphenol copolymer.
The grafted polyphenylene ethers used equally
to these homopolymers and copolymers in this invention
are obtained by grafting vinyl aromatic compounds such as
styre~e, alpha-methylstyrene, vinyltoluene and vinylxylene
to these homopolymers or copolymers t and include, for
example, styrene-grafted poly(2,6-dimethyl-1,4-phenylene)
ether, and a styrene-grafted 2,6-dimethylphenol/2~3,6-
trimethylphenol copolymer.
Preferably, such grafted polymers have a grafting
ratio of about 10 to about 50%, especially about 20~ to
about 40%.
Among these polyphenylene e-thers, p~ly(296-
dimethyl-1,4-phenylene)ether, a 2,6-dimethylphenol/2,3,6-
trimethylphenol copolymer, and grafted polyphenylene ethers
l 1 783
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obtained by grafttng styrene to such polymers are
especially preferred for use in this invention.
The resin matrix in the composition of -this
invention may be composed of such a polyphenylene ether
5 alone, or a mixture o~ it with another polymer. m e
other polymer may be a thermoplastic resin or an elastomer.
The thermoplastic resin as referred to herein
is a resin containing at least 25~ by weight of a recurring
structural unit of the following general formula (III)
R7
-C-CH2~
I (III)
~ ~Z)P
wherein R7 represents a hydrogen atom or a
lower alkyl group, Z represents a halogen a-tom
or a lower alkyl group, and p is 0 or a positive
integer of 1 to 3,5 in the polymer chain~
The lower alkyl group for R8 and Z is, for
example, methyl or ethyl, and examples of the halogen
atom for Z are chlorine and bromine.
Examples of such a thermoplastic resin are
polystyrene, a rubber-modi~ied polystyrene (a high-
impact polystyrene), a styrene/butadiene copolymer, a
styrene/butadiene/acrylonitrile copolymer, a styrene/
acrylic rubber/acrylonitrile copolymer, a styrene/alpha-
~ethylstyrene copolymer, and a styrene/butadiene block
copolymer.
At leas-t one such -thermoplastic resin can be
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l l783~8
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used in combination with the polyphenylene ether.
The thermoplastic resin may be included in the
resin matrix in an amount of preferably not more than 95%,
especially preferably not more than 80/
The elastomer which may be used in this invention
is an elastomer in the ordinary sense Accordingly, the
elastomer in this invention, for example, includes polymers
having a Young's modulus at ordinary temperature of 105 to
109 dynes/cm2 (0.1 to.1020 kg/cm2), the Young's modulus
being defined at pages 71 to 78 of A. V. Tobolsky,
"Properties and Structurss of Polymers" (John Wiley ~ Sons,
Inc., 1960).
Examples of such an elastomer include poly-
butadiene, polyisoprene, a nitrile rubber, an ethylene/
propylene copolymer, an ethylene/propylene/diene copolymer
(~.P~M), polypentenamer, Thiokol rubbers, polysulfide
rubbers, an acrylic rubber, a polyurethane rubber, a
grafted product formed between a butyl rubber and poly-
ethylène, polyester elastomers, and block copolymers,
such as A-B-A' type block copolymers and A-B'-A' type
block copolymers o~ diene compounds and vinyl aromatic
compounds,
In the above A-B-A' type block copolymers and
A-B'-A' type block copolymers, the terminal blocks A and
A' are polymer chain blocks o~ the vinyl aromatic compounds.
The central block B in the A-B-A' type block copolymers
is a polymer chain block of a conjugated diene, and the
central block B' in the A-B'-A' type block copolymers is
a block resulting ~rom the hydrogenation of a polymer
~ 178388
_ g _
chain block of a conjugated diene.
In the above description, the diene, diene com-
pound and conjugated diene are used in the same sense,
and may, for example, specifically represent 1,3-butadiene,
2,3-dimethylbutadiene~ isoprene, 1,3-pentadiene or a
mixture of these. The vinyl aromatic compound may, for
example, denote styrene, alpha-methylstyrene, vinyltoluene 9
vinylxylene~ ethylvinylxylene, vinylnaphthalene, or
mixtures thereof.
Preferably, the aforesaid A-B-At type block
copolymers or A~B'-A' type block copolymers are used as
~le elastomer in this invention. The terminal blocks A
and A' of these block copolymers preferably have a number
average molecular weight of about 2~000 to about 100,000,
and the central blocks B and B' pre~erably have a number
average molecular weight oP about 25,000 to about 1,000 9 000.
The elastomer may be included in the resin
composition of this invention in an amount oP preferably
not more than 2~o by weight, especially preferably not more
than lOyo by weight, based on -the resin matrix.
In the polyphenylene ether resin composition of
this invention, the polyphenylene ether may be incl~de~
in an amount of at least 5% by weight, preferably at
least 15% by weight, based on the resin matrix.
` In the polyphenylene ether type resin composition
oP this invention, the polyphenylene ether resin matrix
composed of the polyphenylene ether alone or a mixture oP
it with the other polymer contains, dispersed therein, a
phosphonous acid or its ester represen-ted by the following
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-- l 1783~8
-- 10 --
formula (I)
p--OR2 (I)
OR3
wherein Rl represents an alkyl group, an aryl group
which may be substituted by an alkyl group, or an aralkyl
group which may be substituted by an alkyl group, R2 and
R3 are identical or different and each represents a
hydrogen atom, an alkyl group~ an aryl group which may be
substituted by an alkyl group, or an aralkyl group which
may be substituted by an alkyl group,
w~ich serves to improve the heat stability of the poly-
phenylene ether.
In the definitions of ~ormula (I), the alkyl
group is preferably an alkyl group having 1 to lO carbon
atoms such as methyl, ethyl, propyl, butyl, pentyl,hexyl,
amyl, octyl9 and decyl. ~xamples of the aryl or aralkyl
group which may be substituted by an alkyl group are
phenyl, naphthyl, diphenyl, benzylphenyl, ben~yl, tri-
phenylmethyl, methylphenyl, dimethylphenyl9 trimethyl-
phenyl and ethylphenyl.
The phosphonous acids(monophosphonous acid)
corresponding to ~eneral formula (I) in which R2 and R3
are hydrogen atoms include ~or example, the compounds
described at page 5 of Gennady M. Kosolapoff, "Organo-
phosphorus Compounds" (John Wiley & Sons, Inc., 1950).
Specific examples of the phosphonous acids are ethyl~
phosphonous acid9 propylphosphonous acid, isopropyl-
phosphonous acid, isobutylphosphonous acid~ isoamylphosphonous
3 ~ 8
-- 11 ~
acid, n-octylpllosphonous acid, benzylphosphonous acid,
triphenylmethylphosphonous acid~ phenylphosphonous acid,
3-methylphenylphosphonous acid 9 2-methylphenylphosphonous
acid, 4-methylphenylphosphonous acid, 4-ethylphenyl-
phosphonous acid, 2,4-dimethylphenylphosphonous acid7
2,5-dimethylphenylphosphonous acid, 2,4,5-trimethylphenyl-
phosphonous acid, 2,4,6-trimethylphenylphosphonous acid,
l-naphthylphosphonous acid, 2-naphthylphosphonous acid,
4-diphenylphosphonous acid, and 4-benzylphenylphosphonous
acid.
Monophosphonous acid esters corresponding to
general formula (I) in which R2 and/or R3 are o-ther than
hydrogen in the above definition can be produced by
reacting the aforesaid phosphonous acids with corresponding
alcohols or aromatic hydroxy compounds. Examples of
these esters include methyl triphenylmethylphosphonite;
dimethyl, diethyl, diisopropyl, dipropyl and diisobutyl
phenylphosphonites; diethyl 4-methylphenylphosphonite;
and diethyl and diphenyl 2,4,5-trimethylphenylphosphonites.
The phosphonous acid or its ester represented
by general formula ~I) may be included in an amount of
about 0.01 to about 10 parts by weight, preferably about
0.05 to about 5 parts by weight, especially preferably
about 0.1 to about 3 parts by weight, per 100 parts by
weight of the resin matrix.
Even when these compounds are used in amounts
exceeding the above upper limits, the heat stability of
the resulting resin composition is not corresponding
improved. Rather, it is frequently deleterious on the
I ~ 78388
- 12 -
properties of the resin composition, resulting in lowered
heat distortion temperatures, for example~ If the amount
of the stabilizer compound is below the specified limit,
the heat stability of the resin composition is not improved
to the expected exten-t.
The resin composition of this invention shows
better heat stability by dlspersing both the above phospho-
nous acid or its ester and at least one sterically hindered
phenol in the matrix resin. It is believed that the
lQ better heat stability is due to the synergistic action of
the two kinds of stabilizer compounds.
Examples of sterically hindered phenols which
can be effectively used in this invention include monohydric
phenols such as 2,6-di-tert -butyl-p-cresol, 2-tert.-butyl-
4-methoxyphenyl, 2,4-dinonylphenyl, octadecyl-3-(3,5-di-
tert.-butyl-4-hydroxyphenyl)propionate, diethyl 3,5-
di-tert -butyl-4-hydroxybenzylphosphonate, and 2-(3',5'-
di-tert -butyl-4'-hydroxyanilino)-4,6-dioctylthio-1,3,5-
triazine; dihydric phenols such as 2,2'~methylenebis(4-
methyl-6-tert.-butylphenol),2~2'-methylenebis(4-ethyl-6-
tert.-butylphenol), butylidenebis(methyl-butylphenol),
4,4'-thiobis(6-tert.-butyl-3-methylphenol), lpl-bis(4-
hydroxyphenyl)cyc~ohexane, 1,6-hexanediol-bis-3-(3,5-
di-tert.-butyl-4-hydroxyphenyl)propionate, 2,2'-
thiodiethyl-bis~3-(3,5-di-tert.-butyl-4-hydroxyphenyl)-
propionate) and N,N'-hexamethylenebis(3,5 di~tert -butyl-
4-hydroxy-hydrocim1amide)~ -trihydric phenols such as
1,3,5-tris(4~tert.~butyl-3-hydroxy-2,6-dimethylbenzyl)-
isocyanuric acid, 2,4,6-tris~3',5'-di-tert.-butyl-4'-
` ;
.
.
~ 1 78~8
hydroxybenzyl)-1,3 9 5-triazine, a triester of 3,5-di-tert.-
butyl-4-hydroxyhydrocinnamic acid with 1,~,5-tris(2-
hydroxyethyl-S-triazine-2~4,6-(lH, 3H, 5H)-trione) and
1~1,3-tris(2'-methyl-4'-hydroxy-5'-tert.-butyl)-phenyl)
butane; and tetrahydric phenols such as pentaerythrityl-
tetrakis(3-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate).
The sterically hindered phenol may be included
in the resin composition of this invention in an amount of
about 0.05 to about 10 parts by weight, preferably about
0.1 to about 5 parts by weight, especially pre~erably
about 0~5 to about 3 parts by weight, per 100 parts by
weight of the matrix resin.
The resin composition of this invention shows
much better heat stability by dispersing an organic mono-
phosphite or organic polyphosphite as well as the phospho-
nous acid or its ester and the sterically hindered phenol
in the resin matri~.
~ xamples of effective organic phosphites for
use in this invention include organic monophosphites such
as triphenyl phosphite, tricresyl phosphite, triisooctyl
phosphite, tridecyl phosphite, tri-2-ethylhexyl phosphite~
trioctadecyl phosphite, tri(octylphenyl)phosphite~ tri(nonyl-
phenyl) phosphite, tridodecylthio phosphite, phenyldiethyl
phosphite, phenyl-di(2-ethylhexyl) phosphite, isooctyl-
diphenyl phosphite, diisooctylmonophenyl phosphite anddi(2-ethylhexyl)mono(isooc-tylphenyl) phosphi-te; and
organic polyphosphites such as a phosphite resin o~
hydrogenated bisphenol A. Among these organic phosphites,
the organic polyphosphites are preferred. An organic
~ 17838
_ 14 ~
monophosphite may be used in combination with an organic
polyphosphite.
The organic phosphite may be included into the
resin composition of this invention in an amount of about
0.05 to about 10 parts by weight, preferably about 0.1 to
about 5 parts by weight9 especially preferably about 0.5
to abou-t 3 parts by weight, per 100 parts by weight of the
resin forming the matrix.
The resin composition of this invention may
further contain various additives depending upon the
intended uses. ~xamples of the additives include lubricants?
such as olefin waxes -typified by polyethylene wax and
polypropylene wax9 phosphate-type fire retardants typified
by triphenyl phosphate or tricresyl phosphate; bromine-
type fire retardants typified by decabromobiphenyl,pentabromotoluene or decabromobiphenyl ether; pigments
typified by titanium dioxide or ~inc oxide; inorganic
fillers typified by glass fibers, asbestos, wollastonite,
mica or`talc; and organic fillers -typified by carbon
fibers. The amounts of these additives vary depending upon
their types 9 but should be within the ranges which do not
degrade the heat stability of -the resin compositian O~f
this invention.
The resin composi-tion of this invention can be
easily produced by melt-mixing methods known with regard
to thermoplastic resins. For example, it can be prepared
conveniently by a method which comprises mixing the
polyphenylene ether or a mixture of it with another
polymer such as a thermoplastic resin or elastomer,
.
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I ~ 783~f~
- 15 -
with predetermined amounts of the phosphonous acid or its
ester J and op-tionally the s-terically hindered phenol and
optionally the organic phosphite in a mixer, then kneading
th~ mixture fully in a mel-t-extruder~ and pelletizing
the rèsulting homogeneous molten mixture.
The following ~xamples and Comparative ~xamples
illustrate the resin composition of this invention more
specifically. Unless otherwise specified, all parts and
percentages in these examples are by weight.
xam~le 1 and Comparative ~xample 1
Sixty (60) parts of a 2,6-dimethylphenol/2,3,6-
trimethylphenol copolymer (2,3,6-trimethylphenol 5 mole%)
having an intrinsic viscosity, measured at 25C using
chloroform as a solvent, of 0.52 dl/g, 37 parts of a
high-impact polystyrene (the polystyrene matrix having an
intrinsic viscosi-ty, measured at 25C using chloro~orm as
a solvent, of 0.89 dl/g; gel content analyzed by using a
mixture of methyl ethylketone and acetone as a solvent of
1~.9% b`y weight), 2 parts of a polystyrene/polybutadiene-
polystyrene block copolymer (the weight ratio of thepolystyrene blocks to the polybutadiene block7 30:70;
the viscosity of a 20/Q toluene solution of the copolymer,
measured at 25C using a Brookfield Model RVT viscometer,
1500 cps), 1 part of an ethylene/propylene copolymer
(having a reduced specific viscosity, measured at 135C in
a concentration of 0.1 g/100 ml using decalin as a solvent,
of 2.0 and a glass transition point of -49C), 5.8 parts
of triphenyl phosphate, 7 parts of titanium dioxide, 0.4
part of phenylphosphonous acid ~C6H5P(OH~2) and 0.6 part
~ 17~8
of 2,2~-methylenebis(4--me-thyl-6-tert.-butylphenol3 were
fully mixed in a .~lenschel mixer. The resulting mixture
~as pelletized by a t~in-screw extruder (AS-30* a product
of l~.~akatani l~ikai Seisakusho) in which the maximum
temperature of the cylinder was set at 290C. A test
specimen, 1/8 inch thick, for measurement of Izod impact
strength was molded from the resulting pellets under an
injection pressure of 1050 kg/cm2 using an injection
molding mac~ine (SJ-35R*~ a product of Meiki Seisakusho).
~.`'ne test specimen was aged in hot air a-t 115C for 10
days. Its Izod impact strength was measured before and
after the aging. The results are tabulated below.
For comparison, the above procedure was repeated
except that the phenylphosphonous acid was not used. The
Izod impact strength of the test specimen not containing
-t~e phosphonous acid was measured and the results are also
tabulated below (~omparative ~xample 1)..
Izod impact strength
(notched, k~-cm/cm)
~g ~
~xample 1 24.0 17.9 (75,~')
Comparative
~xample 1 18,0 11.3 (63/~)
In the above and subsequent tables, the paren-
thesized figures show the percent retention calculated as
follows:
Izod impact strength
Retention (~u) = aftdr a~in ~ t h x 100
be~ore aging
*Trade Mark
B
t8~88
-- 17 --
The above table clearly shows that the use of
phenylphosphonous acid improved the Izod impact strength
of the molded product after the aging.
Th2 pellets produced in Example 1 and Comparative
Example 1 were left to stand for 60 minutes in the molten
state in the cylinder of an injection molding machine in
which the maximum temperature of the cylinder was set at
280C 9 and thereafter in~ection-molded -to prepare test
specimens for measurement of Izod impact streng-th~ The
results are tabulated below together with the data obtained
in Example 1.
Izod impact strength
(notched, kg-cm/cm)
Method of A~ter 60 minute
~xample 1 standing
~xample 2 24.0 14.2 (59%)
Compara-tive
Example 2 18.0 6,1 (34%)
It is seen from the above -table that the resin
composition of this invention shows a high retention of
Izod impact strength even after it has been subjected to
a heat history a-t high temperature.
The procedure of Example 2 was repea-ted except
that 1 part of phenylphosphonous acid was used instead of
0.4 part of phenylphosphonous acid and 0.6 part of 2,2'-
methylenebis(4-methyl-6-tert.-butylphenol). The test
specimen was examined for Izod impact strength ln the same
way as in Example 2.
:'
3 ~ ~
- 18 -
For comparison, the result of Comparative
~xample 2 wherein the phenylphosphonous acid Wfl8 not
used is tabulated bel~w together with the result of
.F,xample 3~
Izod impact strength
(notched; k~-cm~cm)
Method of A~ter 60 minute
~xample 3 21.8 10.5 (48%)
Comparative
~xample 2 18 r 0 6 ~1 ( 34%~
It is seen from the above table that even when
phenylphosphonous acid alone is used as a stabilizer, the
resin composition o~ this invention shows a high retention
of Izod impact strength after it has been subjected to a
heat history~
39 Parts of poly(2,6-dimethyl-1,4-phenylene)
ether having an intrinsic viscosity, measured at 25C in
chloroform, o~ 0.54 dl/g, 59 parts of the same high-
impact polystyrene as used in ~xample 1, 2 parts of thesame polystyrene/polybutadiene/polystyrene block copolymer
as used in Example 1, 10.5 parts of triphenyl phosphate,
7 parts of titanium dioxide, 0.4 part of diethyl phenyl-
phosphonite and 0.6 part of 2,6-di-tert,-butyl-p-cresol
were fully mixed in a Henschel mixer. The mixture was
pelletized by a twin-screw extruder (AS-30, used in
~xample 1) in which the maximum temperature of the cylinders
was set at 290C. The pellets were injection-molded under
an injection pressure of 1050 kg/cm2 using an in~ection
~ ,
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I ~ 783~8
-- 19 --
molding machine (SJ-35B, used in Example l) to prepare a
test specimens~ l/8 inch thick, for measuremen-t of Izod
impact strength~ The resulting test specimen was aged in
hot air at 85C for 20 hours, and its Izod impact strength
was measured be~ore and after the aging. The results are
tabulated below.
For comparison~ the above procedure was repeated
except that the diethyl p~enylphosphononite and 2,6-
di-tert.-butyl-p-cresol were not used. The results are
also tabulated below (Comparative ~xample ~).
Izod impact strength
~ ~E~
Example 4 12.1 10.5 (87%)
Comparative
~xample 3 ' 10.2 7.6 (75~/D)
xample 5 and Comparative ~xam~l,e 4
85 Parts of the same 2,6-dimethylphenol/2,3,6-
trimethylphenol copolymer as used in ~xample l, 15 parts
of the same high-impact polystyrene as used in ~xample l,
5 parts of titanium dioxide, 0.4 part of phenylphosphonous
acid and 1.6 parts of pentaerythrityl-tetrakis(3-(3,5-di-
tert,-butyl-4-hydroxyphenyl)propionate) were fully mixed
in a Henschel mixer. The resulting mixture was pelletized
by a twin-screw extruder (AS-30, used in ~xample l) in
which the maximum temperature of the cylinders was set
at 300C. The pellets were injection-molded under an
injection pressure of 1320 kg/cm2 by an injection molding
machine (SJ-~5B, used in ~xample 1) in which -the maximum
- l ~7838
- 20 -
temperature of the cylinder was set at 320C, to prepare
a test specimen, 1j8 inch thick, .~or measuremen-t of Izod
impact strength. The tes-t specimen was.aged in hot air
at 120C for 100 hours. m e Izod impact strength o~ the
specimen was meas.ured before and after the aging, and
the results are tabulated below.
For comparison, the abo~e procedure was
repeated except that the stabilizer compounds were not
added. The results are also shown in the following table
(Comparative ~xample 4).
Izod impact strength
(notched, kg-cm/cm ~
Before agi~ e~E
~xample 5 9, 0 7 . 5 (83%)
Comparative
Example 4 8.8 5. 3 (6~/o)
~ .'
