Note: Descriptions are shown in the official language in which they were submitted.
1 33 9 1 7 1
This application is a division of Canadian Application
Serial Number 578,882 filed on September 29, 19~8.
FIELD OE INVENTION
This invention relates to polyester polymeric
materials and particularly polybutylene terephthalate having
improved toughness and impact strength and to materials and
methods for producing same.
DESCRIPTION OF PRIOR ART
As described in Olivier International apPlication
W0-86/04076, published on July 17, 1986, the utility of thermo-
plastic polyesters in engineering type applications is limited
where toughness and high impact strength are required. Unmodified
thermoplastic polyesters typically exhibit room temperature impact
strength of 1 ft-lb/inch of notch or less on the Izod scale of
impact strength.
Improvement of the toughness and impact strength of
thermoplastic polyester has been the subject matter of consid-
erable research and development by the most highly skilled in
the art. Much of such earlier research and development has
been addressed to the admixture of additives to the polyester,
with particular attention being given to the addition of rubber-
like or elastomeric materials, such as ethylene-propylene copoly-
mers (EPM) or ethylene propylene-polyene terpolymers (EPDM),
with a view towards improving impact strength and toughness
without interfering with other of the desirable properties of
, -- ~
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133917~
the polyester. The desired level of improvement has not been
achieved with the addition of such rubber-like or elastomeric
materials by reason of the relative incompatibility between
such rubber-like or elastomeric materials and polyester resins.
Attempts have been made to overcome this problem and
increase the compatibility between the rubber-like or elasto-
meric materials and polyester resins by modification of the
rubber-like or elastomeric materials to provide sites that
enable the polyester or polycarbonate resins to adhere to the
elastomeric materials.
Cope, in U.S. patent No. 3,435,093, discloses blends
of polyethylene terephthalate and an ionic hydrocarbon
copolymer of ~-olefins of the formula R-CH=C~2 in which R is
hydrogen (ethylene) or an alkyl radical of 1-3 carbon atoms
(propylene-pentene) with the copolymer modified with an ~,B-
ethylenically unsaturated carboxylic acid containing 3-5
carbon atoms. The Cope patent does not teach or suggest the
components of the additive employed or the concepts employed in
the practice of the invention described and claimed herein, as
will hereinafter appear.
The problem was faced directly in the Epstein U.S.
patent No. 4,172,859, issued October 30, 1979. The Epstein
patent is somewhat confusing in that it seeks to cover the
waterfront by listing an endless number of materials and
combinations thereof for use as additives to improve the
touqhness and impact strength of polyester and polycarbonate
resins. In the Epstein patent, emphasis is placed on the
importance of the particle size and tensile modulus of the
copolymer additive. While Epstein contemplates the use of ethylene-
propylene copolymers and ethylene-propylene-polyene terpolymers,
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1339171
from amongst the large number of other varieties of materials,
and the use of ~,B-ethylenically unsaturated carboxylic and
dicarboxylic acids and anhydrides as modifying agents to pro-
vide sites which adhere to the matrix resin, the Epstein patent
does not recognize the concepts of the invention described and
claimed as will hereinafter be pointed out.
In the aforementioned copending application, of which
this is an improvement, the invention described therein is based
on the thought that an ethylene, C3-C16 mono-olefin, polyene
interpolymer and preferably an ethylene, propylene, diene rubbery
interpolymer would make a good impact modifier for thermoplastic
polyester, if the two could be made compatible. The two are
relatively incompatible because the rubber is a hydrocarbon
while the polyester is a much more polar substance. Thus, the
objective of the invention described and claimed therein was
addressed to the modification of the ethylene, mono-olefin,
polyene interpolymer rubber greatly to improve its compatibil-
ity with polyester resins to provide an improved impact modifier
for the thermoplastic polyester resin.
Briefly described, the features of the invention of
the copending application are embodied in a composition
comprising 60-90 percent by weight of a matrix resin in the
form of a polyester blended with 10-40 percent by weight of an
unsaturated rubber formed by copolymerization of ethylene - one
or more mono-olefins and one or more polyenes in which the
backbone rubber component has been modified with an ester of an
~,B-unsaturated acid having an epoxide functionality on the
alkoxy portion, such as the ester derived from methacrylic acid
and an epoxy alcohol and which attaches to the backbone rubber
chiefly by way of a grafting reaction with little if any
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J~ -3-
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cross-linking reaction.
Polyesters and their method of manufacture are well
known to the skilled in the art and are readily availa~le in
commerce. The invention was described therein with reference
to polybutylene terephthalate as a preferred polyester such as
marketed by the General Electric Plastics Company under the
trademark Valox 310 and Valox 315, although others of the poly-
esters such as described in the above-mentioned Epstein U.S.
patent No. 4,172,859 could be used in the practice of the de-
scribed invention for their improvement in toughness and impac~
strength.
DESCRIPTION OF THE INVENTION
While an ethylene-propylene-polyene ~EPDM) inter-
polymer which has been grafted with an epoxide functional ester
of an ~,B-unsaturated acid markedly improves the notched Izod
impact strength of polybutylene terephthalate (P8T) resins,
deficiencies have been found to exist with respect to the
unnotched Izod impact strength at the knitline. It has been
found, in accordance with the practice of this invention, that
controlled cross-linking of the rubber backbone phase of the
modifier (grafted EPDM) provides a significant improvement in
the knitline strength of the PBT-modifier blend; (1) when a
cross-linking reaction is carried out after proper dispersion
of the grafted rubber in the plastic matrix and (2) when the
cross-linking is limited primarily to the rubber phase of the
blend. Under these conditions improvement in knitline strength
can be achieved while still maintaining good notched Izod im-
pact strength.
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1 339 1 7 1
DETAILED DESCRIPTION OF THE INVENTION
Description will first be made of the preparation of
the grafted backbone rubber. The backbone rubber is formed by
interpolymerization of monomers of ethylene, one or more higher
mono-olefins having from 3-16 carbon atoms, preferably propy-
lene, plus one or more polyenes.
The polyene monomer containing a plurality of carbon-
to-carbon double bonds may be selected from those disclosed in
the prior art for use as third monomers in the preparation of
ethylene-mono-olefin-polyene terpolymers, including open chain
polyunsaturated hydrocarbons containing 4-20 carbon atoms, such
as 1,4-hexadiene, monocyclic polyenes and polycyclic polyenes.
The polyunsaturated bridged ring hydrocarbons or halogenated
bridged ring hydrocarbons are preferred. Examples of such
bridged ring hydrocarbons include the polyunsaturated deriva-
tives of bicyclo (2,2,1) heptane wherein at least one double
bond is present in one of the bridged rings, such as dicyclo-
pentadiene, bicyclo(2,2,1)hepta-2,5-diene, the alkylidene
norbornenes, and especially the 5-alkylidene-2-norbornenes
wherein the alkylidene group contains 1-20 carbon atoms and
preferably 1-8 carbon atoms, the alkenyl norbornenes, and
especially the 5-alkenyl-2-norbornenes wherein the alkenyl
group contains about 3-20 carbon atoms and preferably 3-10
carbon atoms. Other bridged ring hydrocarbons include poly-
unsaturated derivatives of bicyclo(2,2,2) octane as represented
by bicyclo(3,2,1) octane, polyunsaturated derivatives of
bicyclo(3,3,1) nonane, and polyunsaturated derivatives of
bicyclo(3,2,2) nonane.
Specific examples of preferred bridged ring compounds
include 5-methylidene-2-norbornene, 5-ethylidene-2-norbornene,
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5-n-propylidene-2-norbornene, 5-isobutylidene-2-norbornene,
5-n-butylidene-2-norbornene, 5-isobutylidene-2-norbornene,
dicyclopentadienes; the methyl butenyl norbornenes such as
5-(2-methyl-2-butenyl)-2-norbornene or 5-(3-methyl-2-butenyl)-
norbornene, and 5-(3,5-dimethyl-4-hexenyl)-2-norbornene. The
elastomer prepared from 5-ethylidene-2-norbornene is much
preferred as it has outstanding properties and produces many
unusual and unexpected results.
The backbone rubber may contain chemically bound
therein molar ratios of ethylene to propylene or other C3-C16
mono-olefin varying between 95:5 to 5:95 ethylene:propylene,
and preferably between 70:30 to 55:45 ethylene:propylene. The
polyene or substituted polyene may be chemically bound therein
in an amount of 0.1 to 10 mol percent, and preferably 0.3 to 1
mol percent, or in an amount to provide an actual unsaturation
level of 2-15 double bonds per 1,000 carbon atoms in the
polymer chain.
The interpolymerization reaction is carried out in
the presence of a catalyst in a solvent medium. The polymer-
ization solvent may be any suitable inert organic solvent that
is liquid under reaction conditions. Examples of satisfactory
hydrocarbon solvents include straight chain paraffins having
from 5-8 carbon atoms, with best results often being secured by
the use of hexane; aromatic hydrocarbons and preferably an
aromatic hydrocarbon having a single benzene nucleus, such as
benzene, toluene and the like; and saturated cyclic hydrocarbons
having boiling point ranges approximating those of the straight
chain paraffin hydrocarbons and aromatic hydrocarbons described
above, and preferably saturated cyclic hydrocarbons having 5-6
carbon atoms in the ring nucleus. The solvent selected may be
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a mixture of one or more of the foregoing hydrocarbons and
preferably a mixture of aliphatic and naphthenic hydrocarbons
having approximately the same boiling range as normal hexane.
It i8 desirable that the solvent be dry and free of substances
that will interfere with the Ziegler type catalyst used in the
polymerization reaction.
The interpolymerization is carried out in the
presence of a Ziegler catalyst of the type well known in the
prior art. Such Ziegler type catalysts are disclosed in a
large number of patents, such as U.S. patents No. 2,933,480,
No. 3,093,620, No. 3,093,621, No. 3,211,709 and No. 3,113,115.
Examples of Ziegler catalysts include metal organic coordinaticn
catalysts prepared by contacting a compound of a heavy metal of
the group IV-a, V-a, VI-a and VII-a of the Mendeleeff periodic
system of elements, such as titanium, vanadium and chromium
halides with an organo-metallic compound of a metal of groups
I, II or III of the Mendeleeff periodic system which contains 2'
least one carbon-metal bond, such as trialkyl aluminum, and
allyl aluminum halides in which the alkyl groups contain from
1-20 and preferably 1-4 carbon atoms.
The preferred Ziegler catalyst for interpolymeriza-
tion is prepared from a vanadium compound and an alkyl aluminum
halide. Examples of suitable vanadium compounds include vana-
dium trichloride, vanadium tetrachloride, vanadium oxychloride,
vanadium acetyl acetonate, etc. Activators which are especial-
ly preferred include alkyl aluminum chlorides of 3,113,115,
having the general formula RlAlC12 and R2AlCl and the
corresponding sesquichlorides of the general formula R3A12C13,
in which R is methyl, ethyl, propyl, butyl or isobutyl. In the
catalyst system, the aluminum to vanadium mol ratio of the alum-
~ .r
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.,,
inum and vanadium compounds may be within the range of 5/1 to
200/1 and preferably within the range of 15/1 to 60/1, with
best results being secured in the ratio of 40 aluminum to 1
vanadium. These same ratios apply with respect to correspond-
ing compounds of others of the heavy metals substituted for the
vanadium compound and the organo-metallic compounds of groups
I, II and III for the aluminum compounds. A catalyst prepared
from alkyl aluminum sesquichloride, such as the methyl or ethyl
aluminum sesquichloride and vanadium oxychloride is preferred
in the ratio of 1 mole vanadium oxychloride per 5-300 moles of
aluminum and more preferably 15-60 moles of aluminum, with 40
moles of aluminum per mole of vanadium yielding the best results.
The polymerization is preferably carried out on a
continuous basis in a reaction vessel closed to the outside
atmosphere, which is provided with an agitator, coolinq means
and conduit means for continuously supplying the ingredients of
the reaction including monomer, catalyst and accelerators and
conduit means for continuously withdrawing solution containing
elastomer, and the catalyst is killed by the addition of a
catalyst deactivator.
The preparation of EPDM polymers is well known and is
fully described in such patents as U.S. patents No. 2,933,480,
No. 3,093,621, No. 3,211,709, No. 3,646,168, No. 3,790,519, No.
3,884,993, No. 3,894,999 and No. 4,059,654, amongst many others.
There are a number of factors involved in the
modification of the backbone rubber for optimum use as an
impact strength improver of polyester resins. It is desirable
to effect modification of the backbone rubber with an agent
which, when bound to the rubber, provides active sites in
the form of epoxide functions. On the other hand, it is
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1 339 1 7 1
desirable to effect modification of the unsaturated backbone
rubber with a modifying agent that involves little, if any,
copolymerization or cross-linking, but instead relies chiefly
on a grafting reaction for attachment to become a part of the
backbone rubber. Too much cross-linking at this stage of the
process of this invention prevents the satisfactory dispersion
of the rubber into the polyester resin, which is required for
notched Izod impact strength improvement and for subsequent
cross-linking $n the presence of the polyester resin. By the
same token, it is desirable, in accordance with the practice of
this invention, to carry out the modification of the backbone
rubber using reactants and conditions which do not favor
cross-linking under reaction conditions.
In these regards, the concepts described herein
differ basically from the teaching of the aforementioned Ep-
stein U.S. patent No. 4,192,859, which does not recognize the
unique function of an epoxide modifier and which favors copoly-
merization as the mechanism for binding modifying agents with
the base polymer. Further, the Epstein patent does not lead
one skilled in the art to make use of an unsaturated ethylene,
mono-olefin, polyene rubber and minimization of a cross-linking
or other reaction that would involve unsaturated carbon-to-
carbon linkages of the base polymer during the reaction to
modify the base rubber.
As the ester of a methacrylic acid which has an
epoxide functionality on the alkoxy portion, it is preferred to
make use of glycidyl methacrylate, although other epoxy
compounds having the following general formula may be used:
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1 339 1 7 1
o
R C - OR'
C = C
R R
in which R' is an organic group having an epoxide functionality
and R is hydrogen, methyl, ethyl, propyl or other alkyl,
aralkyl, cyclic, or aromatic group. Representative of such
other modifying agents are glycidyl acrylate, glycidyl
2-ethylacrylate, glycidyl 2-propylacrylate and the like.
The catalyst is one that favors grafting reaction as
compared to a cross-linking reaction under the reaction condi-
tions to combine the epoxide modifying agent with the unsatur-
ated backbone rubber. For this purpose, it is preferred to
make use of a free radical initiator such as a dialkyl per-
oxide. In the grafting reaction, use can be made of the
catalyst in an amount within the range of 1-5 parts per 100
parts by weight of the unsaturated rubber, and preferably in an
amount within the range of 1-2 percent by weight.
The level of graft of the epoxy modifying agent onto
the unsaturated backbone rubber is somewhat dependent on the
amount of unsaturation in the backbone rubber. It is desirable
to make use of an ethylene, mono-olefin, polyene backbone
rubber having at least 1.5 unsaturated carbon-to-carbon
linkages per 1000 carbon atoms and little additional benefit is
derived from the use of an unsaturated backbone rubber having
more than 20 carbon-to-carbon double bonds per 1000 carbon
atoms. In the preferred practice of this invention, use is
made of an unsaturated rubber having from 2-15 carbon-to-carbon
double bonds per 1000 carbon atoms or which provide for a level
of graft within the range of 1-10 percent and preferably 1.5-4
~ercent by weight of the rubber.
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133ql71
The preparation of unsaturated rubbers having the
described characteristics are fully described in U.S. patent
No. 3,894,999 and others of the aforementioned patents.
They are commercially available under the trade name EPsyr.270A
(4.5 C~C per lOOOC); EPsyn~55 (9.0 C=C per lOOOC), etc.
marketed by Copolymer Rubber and Chemical Corporation of Baton
Rouge, Louisiana.
The grafting reaction is carried out in solvent
solution with the unsaturated rubber present in a concentration
which may range from 10-30 percent by weight, with constant
stirring, at an elevated temperature within the range of
125-200~C for a time ranging from 1/2-2 hours. The reaction
condition can be varied depending somewhat upon the type and
amount of catalyst ar.d temperature conditions, as is well known
to the skilled in the art.
For a more detailed description of the grafted rubber
and its method of preparation, reference can be made to the
aforementioned Olivier International application published on
July 17, 1986 as W0-86/04076.
Description will hereinafter be made of the features
of this invention wherein improvements in the knitline strength
of the polyester-rubber blend can be achieved without notice-
able loss of notched Izod impact strength. It has been found
that the desired improvement results when the grafted rubber
phase has been dispersed in, at least a part of, or all of the
plastic phase prior to reaction to effect a cross-linking
reaction and when the cross-linking reaction is caused to take
place through either residual unsaturation or residual epoxy
groups in the dispersed rubber phase.
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133~t71
As the cross-linking agent which favors cross-linking
through residual unsaturation in the grafted rubber, it is pre-
ferred to make use of multifunctional molecules or compounds
with functionalities capable of reaction with the grafted
rubber. For this purpose, use can be made of diacids or their
corresponding dianhydrides and/or diamines such as hexamethy-
lene diamine (HDA), melamine, benzophenone tetracarboxylic
dianhydride, adipic acid, maleic acid or anhydride, or other
polyfunctional epoxide reactive compounds.
The described improvement in knitline strength can be
achieved when the grafted rubber moiety contains from 1.5-20
unsaturated carbon-to-carbon linkages per 1000 carbon atoms in
the EPDM rubber component and preferably 2.0 to 15 carbon-to-
carbon double bonds per 1000 carbon atoms. The amount of cross-
linking agent introduced into the dispersion for reaction will
depend somewhat on the amount of unsaturation in the base
rubber and its degree of graft. Improvement is achieved when
the cross-linking agent is reacted in an amount within the
range of 0.4-5 parts per hundred parts by weight of the grafted
rubber and preferably within the range of 0.5-3 parts per 100
parts by weight of the grafted rubber moiety. The level of the
cross-linking agent is adjusted according to its molecular
weight and the number of functional groups per molecule as is
well known to those skilled in the art.
As previously pointed out, the cross-linking reaction
is preferably carried out after the grafted rubber has been
dispersed by blending with the matrix plastic or polyester resin.
Improvement in knitline strength can also be obtained when
the grafted rubber is cross-linked prior to b~ending with the
polyester matrix resin or simultaneously with the blending of
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- the grafted rubber with the polyester matrix resin. In cases
of prior cross-linking of grafted rubber, however, the notched
Izod impact strength of the blend was found to suffer.
The cross-linking reaction is preferably carried out
in bulk, as by working the dispersion of grafted rubber in the
plast$c material in the presence of the cross-linking agent and
at elevated temperature, such as in an extruder, Banbury, Bra-
bender Plasticorder or the like. The temperature for carrying
out the cross-linking reaction may range from 350-500~ F and
preferably within the range of 400-500~ F.
Having described the basic concepts of this inven-
tion, illustration will now be made by way of the following
examples:
Example 1 - Preparation of grafted EPDM.
The starting polymer is a 2.3 RSY EPDM having an
ethylene/propylene molar ratio of 65/35 and having as the
termonomer S-ethylidene-2-norbornene, at a level of seven
weight percent.
Three hundred grams of the starting rubber, 0.3 grams
of Irganox 1076 commercial phenolic antioxidant (Ciba Geigy),
and 1150 grams of hexane were charged to a one-gallon Hastelloy
C reactor. The ~eactor was sealed, flushed with nitrogen, and
heated to 155~ C. Thirty grams ~10 parts per 100 part~ rubber)
of glycidyl methacrylate in fifty grams of hexane was pressured
into the reactor. This was followed by six grams (2 parts per
100 parts rubber) of dicumyl peroxide (~ercules Di-CUp T) in
fifty grams of hexane. The solution was stirred at 500-600 rpm
for one hour at 155~ C and 200-250 psig. After the reaction mix-
ture cooled down, the product was recovered by precipitation in
3 acetone followed by drying overnight at 75~ C under vacuum.
133~171
Analysis of a purified sample of the product indicated 2.8 weight
percent bound glycidyl methacrylate (GMA). The product had an
~SV of 2.2 and a melt flow of 1.2 9/lO miutes. The product was
gel free.
Additional examples for preparation of suitable
grafted EPDM rubbers which differ ln molecular weight, as meas-
ured by viscosity, and the amount of unsaturation and with
different grafting agents are given in the aforementioned co-
pending Olivier application.
The procedure for blending the grafted EPDM
(EPDM-g-GMA) with the polyester and for carrying out the
cross-linking reaction was as follows:
~ lends containing 20~ of the EPDM-g-GMA and 80~
polybutylene terephthalate plastic (PBT) (Valox~315 General
Electric Company) were prepared using a specified number of
extrusions through a 1~ 8ingle-screw extruder (Rillion~having
A L/D ratio of 20/1. Temperatures used for extrusion were 45~~
F in the barrel and 425~ ~ at the die; the screw speed was
approximately 35 rpm. The extruded strands were air-cooled and
pelletized, and then molded into standard Izod bars (5~ x 1/2~
x 1/8~) using a plunger injection molder. The cavity tempera-
ture was maintained at 540~ F, and the mold temperature at
200~ F. The knitline impact samples were molded using a double-
gated mold on a screw injection molder, operated with a nozzle
temperature of 510~ F, a mold temperature of 140~ F, and a
cycle time of 25 secs. The molded test specimens were stored
in moisture-proof polyethylene bags for 16-24 hours before test-
ing. Notched Izod impact strength was measured according to
ASTM D256. Rnitline impact strength was measured on unnotched
double-gated samples, in a manner similar to ASTM D256.
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1339171
Example 2 - Control.
A composition containing 20 percent by weiqht EPsyn
55-g-2.8%GMA, an EPDM of Example 1 grafted to contain 2.8
percent bound qlycidyl methacrylate, and 80 percent by weiqht
Valos 315, a polybutylene terephthalate of the General Electric
Company of Schnectady, New York, was blended for three passes
according to the conditions described in the blending procedure.
The notched Izod impact strength measured 13.5
ft-lbs/inch and the knitline unnotched Izod impact (KLUNI) was
2.2 ft-lbs/inch.
Example 3
The EPsyn 55-g-2.8% GMA from Example 2 was mixed in a
Brabender at 150- C with 0.5 parts per hundred parts of rubber
(phr) 1,6 hexamethylene dia~ine (HDA). Twenty parts by weight
of this material was then blended with eighty parts by weight
Valox 315 by three passes in the extruder. The resulting
modified PBT had a notched Izod of 12.6 ft-lbs/inch, and a
KLUNI of 4.0 ft-lbs/inch.
Example 4
Same procedure as in Example 3, except that 1.25 phr
of 1,6 HDA was used. Notched Izod measured at 1.5 ft-lbs~inch,
and KLUNI at 6.9 ft-lbs/inch.
Example 5
A blend of 20 parts of the EPsyn 5s-g-2.8~GMA of
Example 1 in 80 parts by weight Valox 315 was prepared by two
passes through the extruder. This blend was then added to the
Brabender Plasticorde~ and mixed with 0.5 phr, 1,6 HDA. The
notched Izod measured at 14.7 ft-lbs/inch, and the KLUNI rose
to 18.0 ft-lbs/inch.
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Example 6
Same procedure as in Example 5, except 0.5 phr 1,6
HDA was mixed with the blend in the extruder instead of the
Plasticorder. Notched Izod measured at 13.6 ft-lbs/inch, and
RLUNI at 16.4 ft-lbs/inch.
Example 7
Same procedure as in Example 6, but 0.36 phr melamine
was used as the cross-linking agent instead of the HDA. The
notched Izod measured at 13.6 ft-lbs/inch, and the KLUNI at
15.7 ft-lbs/inch.
Example 8
Same procedure as in Example 6, but 1.39 phr Benzo-
phenone tetracarboxylic dianhydride (BTDA) was used instead of
the 1,6 HDA as the cross-linking agent. Notched Izod measured
at 13.8 ft-lbs/inch and RLUNI at 18.1 ft-lbs/inch.
Example 9
Same procedure as in Example 6, but 1.44 phr adipic
acid was used instead of the HDA. Notched Izod measured at
13.5 ft-lbs/inch, and RLUNI at 15.5 ft-lbs/inch.
Example 10
Same procedure as in the control, but 0.8 phr of 2,5-
dimethyl-2,5-di~t-butylperoxy) hexane (DBPH) was used as the
cross-linking agent. Notched Izod measured at 0.87 ft-lbs/inch,
and RLUNI at 7.4 ft-lbs/inch.
Example 11
Same procedure as Example 6, but 1.6 phr of DBPH was
used as the cross-linking agent instead of the 1,6 HDA.
Notched Izod measured at 12.7 ft-lbs/inch, and RLUNI at 4.5
ft-lbs/inch.
.= ~
2~ .
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1339171
Example 12
Same procedure as in the control, but the modifier
was 17.5% EPsyn 55-g-2.8%GMA and 2.5% EP-g-2.6~ maleic
anhydride (MAH), an ethylene-propylene copolymer grafted to
contain 2.6% bound maleic-anhydride. ~This anhydride
functionality was used to provide "rubber-bound cross-linking
sites.~) Notched Izod meas~red at 2.1 ft-lbs/inch, and RLUNI
at 11.8 ft-lbs/inch.
Example 13
Same procedure as in Example 6. However, the
modifier was 17.5% EPsyn-55-g-2.8%GMA, and was blended with
Valox 315 PBT for two passes in the extruder. Subsequently
2.5~ EP-g-2.6%MA~ was added and two more passes were made.
Notched Izod measured at 12.1 ft-lbs/inch, and RLUNI at 11.9
ft-lbs/inch.
The conditions of preparation and pertinent biend
properties of Examples 2-13 are summarized in Table I below.
TABLE I
Equipment( 1Crosslinking Level 7 ~
ExamD'e Used Agent(phr) Timing( )Nl~ ) KLUNI~
2 BB None - . - 13.52.2
3 BB HDA(2) o 5 Before 12.64.0
4 BB HDA 1 25 Before 1.56.9
BB HDA 0.5 After 14.718.0
6 Extr. HDA 0.5 After 13.616.4
7 Extr. Melamine0.36 After 13.615.7
8 Extr. BTDA(3)1.39 After 13.818.1
9 Extr. AA(4) 1.44 After 13.5 ~ 15.5
BB DBPH(5) 0.8 Before 0.87 7.4
11 E~tr. DBPH 1.6 After 12.7 4.5
12 BB EPM-g-MAH(6) 14.3 Before2.1 11.8
13 Extr. EPM-g-MAH14.3 After 12.1 11.9
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1339171
(1) BB ~ 8rabender Plasticorder; Extr. z Single Screw ex-
truder.
(2) HDA ~ 1,6 ~exane diaminc.
(3) BTDA ~ Benzophenone tetracarboxylic dianhydride.
(~) AA ~ Adipic acid.
(5) DBPH ~ 2,5-dimethyl-2,5-di~t-butylperoxy) hexane.
(6) EPM-g-MAH 3 Ethylene propylene copolymer qrafted to -
contain 2.6~ bound maleic anhydride.
(7) Order of addition of cross-linking agent relative to
dispersing the modifier in the polyester.
~8) Notched Izod lmpact strength, ft.-lbs./inch.
~9) ~nitline unnotched Izod impact strength, ft.-lbs./inch.
A comparison of the knitline unnotched impact strength
of Example 2, having no cross-linking agent, and those of Exam-
ples 3-13, containing a cross-linking agent, clearly demon-
strates an improvement in knitline strength achieved by cross-
linking the modifier phase. It-will be noted that, although
improvement in knitline strength is re~lized in all cases where
a cross-llnking agent is used, the improvement proceeds witho~t
deterioration of notched Izod ~mpact strength, when the cross-
linking agent is added to a blend containinq the predispersed
modifier. Furthermore, the examples demonstrate the utility of
diamines (Examples 3-6), triamines (Example 7), dianhydrides
(Example 8), diacid (Example 9), peroxides (Examples 10, 11)
and polymers ~Examples 12, 13) as cross-linking agents for the
modified polyester blends of this invention.
As described in the aforementioned Olivier
International publication W0-86/04076 on 07/17/86, when the
EPDM rubber is grafted with an epoxy functional ester of
acrylic acid, optimum results are incapable of being
achieved, perhaps because of excess cross-linking taking
place during the grafting reaction whereby the grafted rubber
~tJ~
t~ -18-
133917~
becomes a poor modif~e~ for polyester ~esins. It is disclosed
in the aforementioned Olivler publication W0-86/04076 that this
deficiency can be overcome somewhat by minimizing the amount of
cross-linking during the grafting reaction there~y to enhance
use of a glycidyl acrylate or other acrylate having an epoxide
functionality in modifying the backbone rub~er for use as a
modifier for polyester resins. It is disclosed in the afore-
mentioned Oliver publication W0-86/04076 that this can be
acheived by carrying out the grafting reaction in the presence
of an additional component that acts to inhibit cross-linking
-~ith the graft monomer during the grafting process as by the
inclusion of, for example, methyl methacrylate as an additional
monomer during graftinq the unsaturated rubber with glycidyl
acrylate. Such acrylate modified backbone rubbers are also
suitable for post dispersion reaction with a cross-linking
agent in accordance with the practice of this invention as
illustrated by the following examples.
Example 14
~ he base rubber of Example 1 was grafted with 5 parts
glycidyl acrylate, S parts methyl methacrylate, and 2 parts
dicumyl peroxide per 100 parts rubber in the manner of Examp!e
1. ~nalysis of a pu~ified sample of the product indicated a
degree of grafting of 2.0~ GA. ~o analysis for bound methyl
methacrylate was made. The product had an RSV of 2.5 and a
melt flow of 0.5 9/lO minutes. The product was gel free.
Example 15
A blend is prepared in the manner and composition of
Example 5, except that the grafted rubber of Example 14 is used
in place of the grafted rubber of Example 1.
.. --1 9--
