Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
W O 94/06864 PC~r/US93/08132
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A PROCESS ~OR PREPARING ~IG~ IMPACT STR~NGT~
POLYET~YLENE TE~EP~T~ALATE/IONOMER BLBNDS ;~
EIELD OF THE INVENTION
This invention relates to a process for preparing
polyethylene terephthalate~ionomer compositions which
exhibit high impact strength and to articles made
therefrom. The process involves melt blending
polyethylene terephthalate with an ionomer of ethylene,
an unsaturated carboxylic acid selected from the group
con~isting of acrylic acid and methacrylic acid wherein
the carboxylic acid groups are neutralized with zinc
ions, and an alkyl acrylate, at a shear rate of 3500 to
7000 reciprocal seconds; and thermoforming the blend
into an article.
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BACKGROUND OF THE INVENTION
Polyethylene terephthalate (PET) is widely used as
an extrusion and injection-molding resin for the
fabrication of various articles for household or
industrial use, including appliance parts, containers, ~-~
and auto parts. Because many of such articles must
withstand considerable temperature changes and~or
physical abuse, it is customary to blend polyethylene
terephthalate with other polymers to improve its impact
resistance as shown by notched Izod impact values.
There are advantages, however, in keeping PET as the
matrix material in PET~polymer blends and those are to ~ -~
retain tensile strength, flexural modulus, elongation
percent, weather resistance and heat deflection
temperature.
U.S. Pat. No. 3,435,093 discloses blends of
polyethylene terephthalate and alpha-olefin~alpha-beta
unsaturated carboxylic acid copolymers wherein the
carboxylic acid groups are 0-100% neutralized by me~al
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cations such as sodium, potassium, calcium, magnesium,
zinc and lead. Moreover, the polyethylene terephthalate -~
is present in an amount of between 55 to 95 weight
percent of the blend. Izod impact values of blends
indicated in the Examples of U.S. Pat. No. 3,435,0g3
range from 27.8 J~m to 59.8 J~m at 23C.
U.s. Pat. No. 4,680,344 discloses blends containing
a linear polyester and at least 60 weight percent of
alpha-olefin~alpha-beta-ethylenically unsaturated
carboxylic acid ionomer neutralized with zinc, calcium,
or magnesium. No third comonomer is present. Izod
impact values of blends indicated in the Examples of
U.S. Pat. No. 4,680,344 range from 26.7 J~m to 1308 J~m
at 23C.
U.S. Pat. No. 4,172,859 discloses multiphase
thermoplastic molding compositions containing 60-99
weight percent of polyester matrix resin, and 1-40
weight percent of ionomer having a particle size in the ~ ~;
range of 0.1-3.0 microns. The compositions are prepared ;
using a multi-screw extruder to generate high shear. ~
U.S. Pat. No. 4,172,859, however, gives no indication of ;~ -
which shearing parameters are critical and no direction
as to which of many shearing block designs are likely to
- be successful to accomplish a shear rate of at least
3500 reciprocal seconds which the present inventors have
determined to be critical.
PCT Application No. WO 92~03505 discloses a
semi-crystalline thermoplastic molding composition
containing 60 to 90 weight percent of a polyester resin
and 10 to 40 weight percent of an ionomer consisting of -
ethylene, an alkyl acrylate and an unsaturated
carboxylic acid. The ionomer has from 20% to 80% of the
carboxylic acid groups neutralized with zinc, cobalt,
nickel, aluminum or copper (II).
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U.S. Pat. No. 4,753,980 discloses toughened
thermoplastic polyester compositions containing 60 to 97
weight percent of a polyester and 3 to 40 weight percent
of an ethylene copolymer such as
S ethylene~methacrylate~glycidyl methacrylate.
U.S. Pat. No. 4,303,573 discloses high velocity
impact thermoplastic polyester compositions containing ~ -
polyethylene terephthalate, 2 to 20 weight percent of an ~ -
ionomeric terpolymer which is the zinc salt of a
terpolymer of ethylene, methacrylic acid, and ;~
isobutylacrylate, and 2 to 20 weight percent of a second
terpolymer of ethylene, propylene, and 1,4-hexadiene `~
which has succinate groups pendant from the copolymer -
chain.
In contrast, the present inventors have
unexpectedly discovered a process for preparing superior -~
impact resistant thermoplastic polyester molding
compositions as determined by notched Izod impact values
which are double the impact values found in the
previously mentioned patents. The process involves melt
blending polyethylene ter-phthalate with an ionomer of ~ i
ethylene, an unsaturated carboxylic acid selected from
the group consisting of acrylic acid and methacrylic
acid wherein the carboxylic acid groups are neutralized
with zinc ions, and an alkyl acrylate, at a critical , ;~
shear rate of 3500 to 7000 reciprocal seconds; and ;~
forming the blend into an article. High impact strength
is obtained even though the inherent viscosity of the
polyethylene terephthalate polyester component is ~ ''",'~''~,'"1'' "
significantly reduced due to the high shearing action.
The high shearing process of this invention which
is used to improve the impact strength of a polyester
thermoplastic composition is contrary to the teachings ;~
of U.S. Pat. No. 4,780,506. Such patent teaches, in
column 2, lines 6 to 13 that high shear blending of
, ~ ,"
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PET~polycarbonate blends with impact modifiers leads to
unpredictable results and transesterification which can
be minimized by the use of inhibitors andXor by lowering
the shear level. ~ -
SUMMARY OF THE INVENTION
It is therefore an object of the present invention
to improve the impact properties of polyethylene
terephthalate~ionomer blends.
Another object of the invention is to provide a
process for preparing polyethylene terephthalate~ionomer
blends under conditions of high shear. -
A further object of the invention is to provide
polyethylene terephthalatexionomer blends which exhibit ;;~;~
excellent mechanical properties such as impact
resistance stress crack resistance and heat resistance
and which display excellent melt flowability at the time
of molding thereof.
These and other objects are accomplished herein by
a process for preparing a polyethylene
terephthalate~ionomer blend which exhibits high impact
strength comprising~
(I) melt blending
(A) 70.0 to 90.0 weight percent of a polyester
which comprises
(1) a dicarboxylic acid component comprising repeat ~-~
units from at least 95 mole percent
terephthalic acid; and
(2) a diol component comprising repeat units from
at least 95 mole percent ethylene glycol based ~
on lOO mole percent dicarboxylic acid and 100 ~ -
mole percent diol said polyester having an
inherent viscosity of 0.4 to 1.2 dl~g; and
(B) 30.0 to lO.O weight percent of an ionomer
comprising repeat units from 80 to 95 weight percent-of
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ethylene and 5 to 20 weight percent of an unsaturated -~
carboxylic acid selected from the group consisting of
acrylic acid and methacrylic acid, and the carboxylic
acid groups being neutralized to the extent of 40 to 95
percent with zinc ions; wherein the combined weights of
(A) and (B) total 100 percent and the blending is
conducted in an extruder capable of providing a shear
rate of 3500 sec~l to 7000 sec~l; and
(II) forming the-blend into an article.
DESCRIPTION OF THE INVENTION
The polyester, component (A), of the present
invention is a polyethylene terephthalate (PET) resin.
The polyethylene terephthalate resin contains repeat
units from at least 95 mole percent terephthalic acid
and at least 95 mole percent ethylene glycol, based on
100 mole percent dicarboxylic acid and lOo mole percent
diol.
The dicarboxylic acid component of the polyester
may optionally be modified with up to 5 mole percent of
one or more differont dicarboxylic acids other than ~-
terephthalic acid or suitable synthetic equivalents such
as dimethyl terephthalate. Such additional dicarboxylic -
acids include aromatic dicarboxylic acids preferably
having 8 to 14 carbon atoms, aliphatic dicarboxylic
acids preferably having 4 to 12 carbon atoms, or ; ~-
cycloaliphatic dicarboxylic acids preferably having 8 to
12 carbon atoms. Examples of dicarboxylic acids to be -
included with terephthalic acid are: phthalic acid,
; 30 isophthalic acid, naphthalene-2,6-dicarboxylic acid,
cyclohexanedicarboxylic acid, cyclohexanediacetic acid,
diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric
acid, adipic acid, azelaic acid, sebacic acid, and the
like. Polyesters may be prepared from two or more of
the above dicarboxylic acids.
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It should be understood that use of the
corresponding acid anhydrides, esters, and acid
chlorides of these acids is included in the term
"dicarboxylic acid". ~ ;
In addition, the polyester, component (A), may -
optionally be modified with up to 5 mole percent, of one
or more different diols other than ethylene glycol.
Such additional diols include cycloaliphatic diols
preferably having 6 to 20 carbon atoms or aliphatic
diols preferably having 3 to 20 carbon atoms. Examples ~ -~
of such diols to be included with ethylene glycol are~
diethylene glycol, triethylene glycol,
1,4-cyclohexanedimethanol, propane-1,3-diol,
butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, ~ ;
3-methylpentanediol-(2,4), 2-methylpentanediol-(1,4),
2,2,4-trimethylpentane-diol-(1,3),
2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3), ;~
hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene, ;
2,2-bis-(4-hydroxycyclohexyl)-propane,
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,
2,2-bis-(3-hydroxyethoxyphenyl)-propane, and
2,2-bis-(4-hydroxypropoxyphenyl)-propane. Polyesters
may be prepared from two or more of the above diols.
The polyethylene terephthalate resin may also
contain small amounts of trifunctional or ~`
tetrafunctional comonomers such as trimellitic
anhydride, trimethylolpropane, pyromellitic dianhydride, -
pentaerythritol, and other polyester forming polyacids - ~
or polyols generally known in the art. -
Polyesters comprising substantially only dimethyl --
terephthalate and ethylene glycol are preferred in the `- i
case where the blends of the present invention are used ;
in making thermoformed crystallized PET articles.
Polyethylene terephthalate based polyesters of the ~ :;
present invention can be prepared by conventional
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polycondensation procedures well-known in the art. Such
processes include direct condensation of the
dicarboxvlic acid(s) with the diol(s) or by ester
interchange using a dialkyl dicarboxylate. For example,
a dialkyl terephthalate such as dimethyl terephthalate
is ester interchanged with the diol(s) at elevated
temperatures in the presence of a catalyst. The
polyesters may also be subjected to solid state
polymerization methods.
The polyester, component (A), useful in the
practice of this invention is the condensation product -~
of terephthalic acid, usually employed as the dimethyl
ester, and ethylene glycol, hereinafter referred to as
polyethylene terephthalate or PET. The PET has a
melting point (Tm) of 255C. +5C. and a glass -~
transition temperature (Tg) of 80C. l5C. The PET may
exhibit a relatively broad molecular weight range as
determined by inherent viscosities of from 0.4 to 1.2.
However, inherent viscosities of from 0.5 to 0.9 are
preferred.
A preferred polyester Sor use in this invention is ~ -~
a crystallized polyethylene terephthalate having an ~ `
inherent viscosity of 0.70 which is commercially~--
available as XODAPAX PET 7352 (trademark) from Eastman
Kodak Company.
Component (B) of the present invention is an
ionomer. Ionomers~suitable for use in the present
invention consist of copolymers and terpolymers of
ethylene, an unsaturated carboxylic acid selected from ~-
the group consisting of acrylic acid and methacrylic
acid and, optionally, an alkyl acrylate having from 1 to
8 carbon atoms in the alkyl group. The carboxyl`~
group-containing copolymers and terpolymers usually are
converted at least in part to the salt form or, are
neutralized to a certain degree. Such neutralization is -~
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WO 94/06864 PCI'/US93/08132
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obtained by adding to the carboxyl group-containing
polymeric material a calculated amount of a zinc salt,
for example, zinc acetate, and heating the mixture to a
temperature below 140C., while thoroughly mixing the
materials together. The resulting partly or completely
neutralized carboxylic group-containing polymeric ~ ~
material is known generically as an ionomer. ~ -
The present inventors have determined through
experimentation that cations other than zinc such as
aluminum, potassium, sodium and magnesium do not result
in improved impact strength for articles incorporating
such carboxyl group-containing copolymers and
terpolymers. The ionomer has from 40 to 80 percent of
the carboxylic acid groups neutralized with zinc.
Preferably, the ionomer has from 50 to 75 percent of the
carboxylic acid groups neutralized with zinc and most
preferably 70 percent. Some of such ionomeric materials :
are available commercially, for example "SURLYN"
(trademark) ionomer resins of the E.I. DuPont de Nemours i~
and Company. Particularly preferred ionomers are SURLYN ` ;
9020 which is a r~ndom terpolymer o~
ethylene~methacrylic acid~isobutyl acrylate 70%
neutralized with zinc, and SURLYN 9721 which is a
ethylene~methacrylic acid copolymer 70% neutralized with -`
zinc. - ~-
The ethylene content of the copolymer or terpolymer
is at least 50 weight percent, based on the i
ethylene~acid copolymer or terpolymer. The unsaturated
carboxylic acid content of the ionomer should fall in
the range of from 2 to 20 weight percent, the preferred i `
range being from 5 to 15 weight percent and the most ~ ~-
preferred range being from 8 to 12 weight percent, based
on the ionomer to give the best combination of low
temperature impact resistance and high temperature ~ -
resistance. The alkyl acrylate content of the
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terpolymer is from 2 to 15 weight percent. Preferably
the alkyl acrylate is n-butyl acrylate or isobutyl
acrylate. Most preferably, the alkyl acrylate is
isobutyl acrylate.
S Ionomer copolymers of this invention preferably
contain repeat units from 80 to 95 weight percent of
ethylene and 5 to 20 weight percent of acrylic acid or
methacrylic acid. Ionomer terpolymers of this invention
preferably contain repeat units from 70 to 90 weight
percent of ethylene, 5 to 15 weight percent of acrylic
acid or methacrylic acid, and 5 to 15 weight percent of
an alkyl acrylate or methacrylate having 1 to 8 carbon
atoms in the alkyl group. -~
Ethylene~methacrylic acid copolymers partially
neutralized with zinc but which do not contain an alkyl
acrylate, for example, isobutyl acrylate, are not as ~ ;- 3
effective as ethylene~methacrylic acid copolymers
partially neutralized with zinc which contain isobutyl
acrylate. The present inventors have determined that
the presence of an alkyl acrylate tends to reduce the
modulus of the ionomer. Isobutyl acrylate, for example, `~
reduces the modulus of the ionomer which in turn gives a
more favorable ratio of PET modulus to ionomer modulus.
The ratio of PET modulus to ionomer modulus should be ~ .
greater than 10:1, and preferably greater than 20:1.
Thus, the absence of an alkyl acrylate necessarily `~
requires higher concentrations of the ionomer in the -~
polyester~ionomer blend in order to obtain high impact
strength. ;
The ionomer generally is present in the blends of
the present invention in an amount of from 10 to 30
weight percent. Consequently, at least 70 weight
percent of the blends is PET. Such critical amounts
take into consideration the advantages which exist in
keeping PET as the matrix material. The-advantages
,
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include retention of tensile strength, flexural modulus,
elongation percentage, and heat deflection temperature.
Preferably the concentration of ionomer should be from
15 to 25 weight percent and most preferably from 18 to -~
22 weight percent.
The compositions of the present invention may be
made from a single polyester resin and a single ionomer
or from a polyester and a mixture of ionomers.
The process for preparing the polyester~ionomer
blends of the present invention involve preparing the ""."~'` ~,'-'!,'.',"','
polyester and zinc ionomer, respectively, by processes
as mentioned previously. The polyester and zinc ionomer
are dried in an atmosphere of dried air or dried ;~
nitrogen, or under reduced pressure. The polyester and
ionomer are blended and subseguently melt blended or
compounded in an extruder operated in a manner to :
provide a shear rate of 3500 sec~1 to 7000 sec~1 in the - `-
melt phase. Such shear rate is essential to provide the
blends of this invention with high impact strength. - `
Preferred extruders are twin screw extruders set up to
provide a shear rate of 3500 sec~1 to 7000 sec~1. The
ionomer(s) are dispersed throughout the polyester as --
discrete particles, which particles have a number
average particle size of less than or equal to 1 micron. '
The zinc ionomer dispersed phase in PET obtained by this `,.
type of blending h~s particle diameters of 0.1 to 0.3
microns.
Torque can be used as a measurement of the amount .
of shear being applied to a blend. The highest impact
properties are achieved with the blends of the present
invention at the maximum torque attainable. The maximum
torque attainable by the present inventors is 102 J~m ; ~ ~ -
which translates into 6000 sec~l. The present
invention, however, is not limited by a torque value of
102 J~m. In fact, higher torque values are expected to ; ~
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result in even greater notched ~nd unnotched impact
strength.
The necessary shearing force can be obtained, for
example, in an extruder such as a Werner and Pfleiderer ~`
ZSX-28mm or ZSK-30mm corotating, intermeshing twin screw
extruder, at a melt temperature of 260C. It is ~- -
important to note that the Werner and Pfleiderer
ZSR-28mm corotating, intermeshing twin screw extruder
has at least two different screw designs, a "hard" screw ~ ;-
design and a "medium" screw design. The "hard" screw
design is a screw configuration which has 215 mm of -
kneading block length, eight elements which slide on, `~
near the center and end of the screw for mixing and
homogenizing the material. Two of the elements are
left-handed elements capable of providing a higher shear
field. A left-handed screw bushing element is included
to back up the flow in the machine to create higher
shear. The total length of the "hard" screw is 800 mm.
Within the "hard" screw-design, there are infinite ~ `
settings that would provide the neces6ary shear. The `~ `
maximum shear rate obtainable with the "hard" screw
design on the Werner and Pfleiderer ZSK-28mm extruder is
5500 sec~l. Thus, the "hard" screw i8 appropriately
named since it is "hard" on the polymer.
The "medium" screw design has a mixing screw which
is the same length as the "hard" screw. The "medium"
screw has 45 mm of kneading block length, four elements
which slide on, near the center and end of the screw for ~-
mixing and homogenizing the material. The maximum shear
rate obtainable with the "medium" screw design is less
than 3500 sec~l. The present inventors have determined
that thè impact strength of blends prepared with the
"medium" screw design on the Werner and Pfleiderer ;
ZSR-28mm extruder have significantly lower Izod impact
values than blends prepared with the "hard" screw
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design. Moreover, the present inventors have determined
that blends prepared on single screw extruders have even
lower Izod impact values than blends prepared with a
Werner and Pfleiderer ZSK-28mm extruder having a i-
"medium" screw design. i ~i
The twin screw configuration required to attain the
high impact compositions of the present invention -
requires that 25 percent of the screw length contain
kneading blocks. These kneading blocks are distributed-ii -
in groups of 2 to 4, for example, and each group is
generally ended with a left-handed kneading block to - ;~
insure that the kneading block groups are being
maintained at full capacity to maximize their mixing -~
capability. However, other configurations that have at -~
least the minimum length of kneading blocks and . ~ . ' r.
left-handed kneading blocks will provide the desired
results. Such configurations provide maximum shear
rates, good extensional flow and backmixing.
Melt temperatures must be at least as high as the
melting point of the polyester component or sufficiently
above the glas~ transition temperature for an amorphous
polyethylene terephthalate polyester, which typically is
in the range of 260-310C. Preferably, the melt -
blending or compounding temperature is maintained as low
as possible within said range. The composition is ;~
molded preferably at 260C. to 280C. under low
temperature mold conditions such as 23C. to provide an
amorphous molded specimen. High impact strength is
obtained even though the I.V. of the polyethylene
terephthalate polyester component has been significantly
reduced due to the high shearing action. After -~
completion of the melt compounding, the extrudate is
withdrawn in strand form, and recovered according to the
usual way such as cutting.
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Under melt processing conditions the PET undergoes - -~
molecular weight degradation in the presence of ~ ~ -
contaminants such as water, thus, it is preferable that
the polyester be incorporated in anhydrous form into the
blends of the present invention. The blends should also
be protected from moisture prior to melt processing. ;~
Many other ingredients can be added to the ,.. ~``
compositions of the present invention to enhance the
performance properties of the blends. For example, `;;~`
surface lubricants, denesting agents, stabilizers,
antioxidants, ultraviolet light absorbing agents, mold
release agents, metal deactivators, colorants such as
titanium dioxide and carbon black, nucleating agents ~ a~
such as polyethylene and polypropylene, phosphate
stabilizers, fillers, and the like, can be included ~:
herein. All of these additives and the use thereof are
well known in the art and do not require extensive
discussions. Therefore, only a limited number will be
referred to, it being understood that any of these
compounds can be used so long as they do not hinder the
present invention from accomplishing its objects.
The blends of the present invention serve as
excellent starting materials for the production of
moldings of all types. Specific applications include
medical parts, appliance parts, automotive parts, tool
housings, recreational and utility parts. The molding
compositions of the present invention are especially
useful in applications that require toughness in hard to
fill injection molded parts. Additionally, the blends
can be used to prepare extruded sheets for thermoforming
applications. :~
The materials and testing procedures used for the
results shown herein are as follows~
Break Elongation: ASTM-D638
Density (gradient tube method): ASTM-D1505
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Flexural Modulus and Flexural Strength: ASTM-790 ` - -:
Heat Deflection Temperature: ASTM-D648
Melt Flow Index- ASTM-D1238
Tensile Strength and Yield Strength: ASTM-T638 ~ ~ -
Izod Impact Strength: ASTM-D256. The Izod Impact ~ - -
Strength Test was repeated three to five times for each - -
material. The letters CB, PB and NB listed under impact
strength have the following meanings:
CB - complete break, brittle failure -
PB - partial break
NB - no break, ductile failure.
Inherent viscosity (I.V.) was measured at 23C.
using 0.50 grams of polymer per 100 ml of a solvent ;;-~
consisting of 60% by weight phenol and 40% by weight
tetrachloroethane. -~
Ionomer A is a 80~10~10 weight percent terpolymer
consisting of ethylene, isobutyl acrylate and -
methacrylic acid, respectively, containing 2.63 weight
percent zinc. The degree of neutralization of the acid
is 69%. Flexural Modulus at 23C. is 14,000 psi (100 ~ `
MPa). Melt Index at 190C. (grams per 10 minutes) is
1Ø Polyester~Ionomer ratio is 10:1. Ionomer A is
commercially available under the trademark SURLYN 9020
from E.I. DuPont de Nemours and Company.
Ionomer 8 is a 80~10~10 weight percent terpolymer
consisting of ethylene, isobutyl acrylate and
methacrylic acid, respectively, with 70% of the carboxyl i~
groups neutralized with sodium. Melt Index at 190C.
(grams per 10 minutes) is 1Ø Polyester~Ionomer ratio
is 10:1. Ionomer B is commercially available under the
trade name SURLYN 8020 from E.I. DuPont de Nemours and
Company.
Ionomer C is a 90~10 weight percent copolymer
consisting of ethylene and methacrylic acid,
respectively, with 70% of the carboxyl groups
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neutralized with zinc. Melt Index at 190C. (grams per
10 minutes) is 1Ø Polyester/Ionomer ratio is
10:1.Ionomer C is commercially available under the trade
name SURLYN 9721 from E.I. DuPont de Nemours and
Company.
Ionomer D is a 90~10 weight percent copolymer
consisting of ethylene and methacrylic acid,
respectively, containing 0.93 weight percent sodium.
The degree of neutralization of the acid is 70%,
flexural modulus at 23C. is 14,000 psi (100 MPa), and
melt index is 1.0 g~10 min @ 190C. Melt Index at
190C. (grams per 10 minutes) is 1Ø Polyester~Ionomer
ratio is 10:1. Ionomer D is commercially available
under the trade name SURLYN 8527 from E.I. DuPont de
Nemours and Company.
In the following examples, all the blends of ;~
neutralized acid copolymer and terpolymer with
polyethylene terephthalate that were prepared on a
Werner and Pfleiderer ZSK-28mm twin-screw extruder with
"hard" screw design utilized the following conditions:
SET TEMPERATURE ~C.)
Zone Zone Zone Zone Zone
1 2 3 4 5
120 237 260 265 267
::: :: :~: ::
MELT TEMPERATURE (C#3)
52 288 ~ 273
DIE TEMPERATURE (C.) TOROUE RPM
825 232 ~4~ ''
.''. .' ` 1 ~ . ~: ' .' '
The resulting pelletized materials were injection molded
on a BOY-22S Injection Molding Machine or on a Toyo T9OG
injection molding machine using the following condition: `
W094/06864 PCT/US93/08132
Open Cycle Time 4 seconds
Injection and Hold Time14 seconds -~
Cooling Time 12 seconds . - -.-~
Injection Time 4 seconds - ~ I
Total Cycle Time34 seconds
Zone 1 240C. ~ -~
Zone 2 260C i--
Mold Temperature 23C
Nozzle temperature 260C.
Screw Speed 125 rpm
Injection Pressure600 psig (4238 RPa)
Hold Pressure600 psig (4238 KPa)
. ::: . ::
The invention will be further illustrated by a
consideration of the following examples, which are ;~
intended to be exemplary of the invention. All parts
and percentages in the examples are on a weight basis
unless otherwise stated.
E~ MPLE
A homopolymer of crystallized polyethylene
terephthalate having an I.V. of 0.70 was dried at 150C.
for 16 hours in desiccant air with a dew point S-29C.
The PET was placed in the hopper, under dry N2, of a
Werner and PSleiderer ZSK-28mm corotating, intermeshing
twin screw extruder having the "hardN screw design. The
PET was melt processed at 260C. under high shear ;
conditions, stranded and pelletized. The I.V. of the
PET was 0.61.
The pelletized PET was dried at 100C. for 8 hours
in desiccant air with a dew point S-29oc- and injection
molded on a Boy 22S injection molding machine using a
melt temperature of 260C. and a mold temperature of ~ ~
23C. to provide an amorphous test specimen. The I.V. ~ ~ -
of the PET after molding was 0. 55 . The impact ~ -~
propertiés of the PET is summarized in Table I. ;`
. .:
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21~20
- 17
EXAMPLE 2
The PET of Example 1 was dried at 150C. for 16
hours in desiccant air with a dew point <-29C. -~
Ionomer A was dried at 60OC. for 16 hours in desiccant
air with a dew point S-29C. The PET and Ionomer A were
pellet blended in a polyethylene bag such that the
concentration of Ionomer A was lO weight percent. The
PET~Ionomer A blend was placed in the hopper, under dry
N2, of a Werner and Pfleiderer ZSK-28mm corotating,
intermeshing twin screw extruder having the "hard" screw
design. The blend was melt processed at 260C. under
high shear conditions, stranded and pelletized.
The pelletized blend was dried at 100C. for 8
hours in desiccant air with a dew point S-29C. and
injection molded on a Boy 22S injection moldinq machine ~-
using a melt temperature of 260C. and a mold
temperature of 23C. to provide amorphous test
specimens. The impact properties of the blend are
summarized in Table I.
EXAMP~ES 3-5
~ he procedure of Ex~mple 2 was followed except that
the concentration of Ionomer A in the PET blend was
changed to provide Ionomer A concentrations of 15, 20
and 30 weight percent, respectively. The effect of the
zinc ionomer concentrations in PET are summarized in ; ;
T~ble T
WO 94/06864 PCT/US93/08t32
- 18
EXAMPLES 6-9
The procedure of Example 2 was followed except that
Ionomer A was substituted with Ionomer B. The ~ ~ ;
concentration of Ionomer B in the PET blends was lo, 15,
20 and 30 weight percent, respectively. The results are
summarized in Table III.
EXAMPLE 10 ; ;~
A blend containing 80 weight percent of the PET of
Example 1 and 20 weight percent of Ionomer A was
prepared as in Example 2 except that a Werner Pfleiderer
ZSX-30mm corotating, intermeshing, twin-screw extruder
was used. The extruder has a screw length of 1061 mm
and 266 mm of this length is comprised of kneading
blocks and left-handed blocks to provide high shear.
The pelletized blend was injection molded on a Toyo T9OG ~ z
molding machine at 265C. The test results are
summarized in Table I.
The results in Table I indicate that essentially
identical high impact strength was obtained with this
blend as was obtained by the same blend in Example 2
which was prepared on the Werner Pfleiderer ZSK-28mm
extruder and molded on the Boy 22S injection molding ~-machine.
- '
~ : :.- '~
.. . ~ .
; .. ~
wos4/o6864 PCT/US93/08132
21 ~ 2 72 o
- 19 - '
TABLE I
Impact Strength of Zinc and Sodium Terpolymer Ionomers
IONOMER IONOMER IZOD IMPACT STRENGT~ (J~m)
A 8 Notched Unnotched Notched Unnotched
EXAMPLE (wt%) ~wt%) (23C.) ~23C.) (-40C.) ~-40OC.)
Ex. 1 0 0 32 2362 30 1949
(5CB) (5NB) (5CB) (3NB,2CB)
Ex. 210 0 70 1754 42 1362
(5CB) (5NB) (5CB) (5NB)
Ex. 315 0 1039 1627 56 1293
(lPB,3NB) (5NB) (5CB) (3NB,2CB)
Ex. 420 01145 1850 75 2200
(5NB) (5NB) (5CB) (5NB)
Ex. 530 01049 1362 236 1606
(5NB) (5NB) (5CB) (5NB)
Ex. 6 0 0 28 2523 24 2215 ~ 5
(5CB) (5NB) (5CB) (3NB,lCB) ~4
Ex. 7 0 10 45 1961 34 2306
(5CB) (5NB) (5CB) (2NB,3CB)
Ex. 8 0 lS S9 1924 34 2809
(5CB) (SNB) (SCB) (2NB,3CB) ;
Ex. 9 0 20 S9 1781 37 2814 ~,;` `,~
(SCB) (SNB) (SCB) (SNB)
Ex. 100 30 101 1754 59 1675 `
(SCB) (SNB) (SCB) (3NB,lCB) ~ "-~
''.' ,:' .''`''~'`";
The data in Table I indicates that significant
increases in notched impact strength are achieved with
the PET~Ionomer A blends in spite of the drastic ;~
reduction in inherent viscosity experienced by the PET ;~
portion of such blends. The decrease in inherent `~
viscosi~y would have been expected to have resulted in a
- severe loss of impact strength rather than an increase.
For example, the notched Izod impact strength at 23C.
of the PET~Ionomer A blend of Example 4 is 1145 J~m and
~ .
~ . ~ ' ' ':'
W O 94/06864 PC~r/US93/08132
~ - 20 ~
no break failure mode compared to 32 J~m and complete
break failure mode for the PET control of Example 1.
The notched Izod impact strength at -40C. of the PET
blend of Example 4 is 75 J~m compared to 30 J~m for the
PET control. ~. `~
The data also indicates that PET~Ionomer A blends
wherein the acid component is neutralized with zinc
exhibit significant increases in notched impact strength
at 23C. and -40C. as compared to PET~Ionomer B blends
wherein the acid component is neutralized with some
other ion such as sodium. Moreover, the mode of impact
failure for the blends utilizing zinc was ductile as
opposed to brittle for the blends utilizing sodium.
The data in Table I further indicates that a preferred
combination of low temperature impact resistance and
high temperature impact resistance was achieved where
the PET~Ionomer A blends contained from 5 to 15 weight --~
percent ionomer. In contrast, Ionomer B which is the
sodium neutralized ionomer, even at the 30 weight
percent level only slightly increased notched Izod
impact strength from the PET control. For example, at
23C. notched Izod impact strength for the PET control ;
is 28 J~m with complete break failure mode, and for the
PET~Ionomer B blend at 30 weight percent ionomer level
is lO1 J~m with complete break failure mode.
: -
EXAMPLE 11
The procedure set forth in Example 2 was followed
except that the pellet blend composition fed into the
Werner and Pfleiderer ZSK-28mm corotating, intermeshing
twin screw extruder having the "hard" screw design ~ ~`
consisted of 40 weight percent PET and 60 weight percent ~ p
Ionomer A. The 40~60 PET~Ionomer A concentrate blend in
pellet form was blended with s~fficient PET pellets to
provide a final concentration of 20 weight percent
W094/06864 PCT/US93/08132
21~272~ . ~
- 21 -
Ionomer A in the PET. The test results are summarized
in Table II. Test results from Example l and Example 4 '~
are included for comparison purposes. - ~,
TABLE II
Effect of PETxIonomer Concentrate
IONOMER IZOD IMPACT STRENGTH (Jxm)
A Notched Unnotched Notched Unnotched
EXAMPLE (wt~ (23C.) (23OC.) (-40C.) (-40OC.)
Ex. 1 0 322362 30 1949
(5CB)(5NB) (5CB) (3NB,2CB) ~
Ex. 4 20 1145 1850 75 2200 "'''''!.''""'"'''
(SNB) (5NB) (5CB) (5NB) , ~ ,,,,",~"
Ex. 11 20 1240 2147 93 2131 '~
(5NB) (5NB) (5CB) (SNB)
The results in Table II clearly show that
essentially identical improvements in impact strength ''''''''~I'''.,~;''A.~'',``,
are obtained by preparing a concentrate of the zinc ,
' ionomer in PET and then adding the additional PET needed ~,''',
to provide the desired ionomer conoentration prior to
molding. ,
EXAMPL~ 12
The PET of Example 1 was dried at 150C. for 16 'i," ~",~",,,~''
hours in desiccant air with a dew point S-29C. '-~
Ionomer A was dried at 60C. for 16 hours in desiccant '~
air with a dew point S-29C. The PET and Ionomer A were
' pellet blended in a polyethylene bag such that the
; concentration of Ionomer A was 15 weight percent. The
PET~Ionomer A blend was placed in the hopper, under dry ,~
N2, of a,'MPM single screw extruder equipped with a
mixing screw. The blend was meltiprocessed at 260C., ,~
stranded and pelletized. ;' ,,
:~ ' '.;
:. ~
W O 94/06864 PC~r/US93/08132
-: .
, :
22 - ' '~
, ~', '::''-
The pelletized blend was dried at 100C. for 8 -
hours in desiccant air with a dew point <-29~C. and ,~
injection molded on a Boy 22S injection molding machine - ,~
using a melt temperature of 260C. and a mold ',~
temperature of 23C. to provide amorphous test
specimens. The impact properties of the blend are ;~
summarized in Table III. ; -'
EXAMPLE 13
The PET of Example 1 was dried at 150C. for 16 ''~
hours in desiccant air with a dew point S-29C.
Ionomer A was dried at 60C. for 16 hours in desiccant ~ '
air with a dew point S-29C. The PET and Ionomer A were '
pellet blended in a polyethylene bag such that the
concentration of Ionomer A was 15 weight percent. The
PET~Ionomer A blend was placed in the hopper, under dry
N2, of a Brabender single screw extruder equipped with a '~
mixing screw. The blend was melt processed at 260C., , i~
stranded and pelletized.
The pelletized blend was dried at 100C. for 8
hours in desiccant air with a dew po,int S-29C. and
injection molded on a Boy 22S injection molding machine
using a melt temperature of 260C. and a mold ~a ~ ,`''
temperature of 23C. to provide amorphous test
specimens. The impact properties of the blend are ~ '' ',,',
summarized in Table III. ; , ,,,~
EXAMPLE 14
The PET of Example 1 was dried at 150C. for 16
hours in desiccant air with a dew point S-29C.
Ionomer A was dried at 60C. for 16 hours in desiccant
air with'a dew point S-29C. The PET and Ionomer A were
pellet blended in a polyethylene bag such that the
concentration of Ionomer A was 15 weight percent. The ~ ~'
PET~Ionomer A blend was placed in the hopper, under dry
~'' ~':
~:
W094/06864 PCT/US93/08132
2 ~ l~ 2 7 2 ~
- 23 -
N2, of a Sterling single screw extruder equipped with a
mixing screw. The blend was melt processed at 260OC.,
stranded and pelletized.
The pelletized blend was dried at 100C. for 8 `
hours in desiccant air with a dew point <-29C. and
injection molded on a Boy 22S injection molding machine - - ~
using a melt temperature of 260C. and a mold -, :
temperature of 23C. to provide amorphous test
specimens. The impact properties of the blend are ~ ~ ~;
summarized in Table III.
EXAMPLE 15
The PET of Example 1 was dried at 150C. for 16 ~- -
hours in desiccant air with a dew point S-29C. ;~
Ionomer A was dried at 60C. for 16 hours in desiccant
air with a dew point S-29C. The PET and Ionomer A were
pellet blended in a polyethylene bag such that the
concentration of Ionomer A was 15 weight percent. The
PET~Ionomer A blend was placed in the hopper, under dry
N2, of a Werner and Pfleiderer ZSK-28mm corotating,
intermeshing twin screw extruder having the "medium"
screw design. The blend was melt processed at 260C.,
stranded and pelletized.
The pelletized blend was dried at 100C. for 8 ;~
hours in desiccant air with a dew point S-29C. and
in~ection molded on a ~oy 22S injection molding machine
using a melt temperature of 260C. and a mold
temperature of 23C. to provide amorphous test -
specimens. The impact properties of the blend are
summarized in Table III.
~, ,.:,
. ,. . ~
, ;, "
.
W O 94/06864 PC~r/US93/08132 -
.
- 24 -
TABLE III
Effect of Different Extruders ~-
IZOD IMPACT STRENGTH (J~m) -
EXTRUDER Notched Unnotched Notched Unnotched
EXAMPLE TYPE (23C.) (23C.) (-400C.) (-40C.
Ex. 12 MPM
Control 39 2321 31 2687 ~ -~
(5CB) (5NB)(5CB) (5NB) ~ ~-
Blend 80 1871 51 2300 ~ -
(5CB) (5NB)(5CB) (5NB)
Ex. 13 Brabender
Control 39 1776 30 2645
(5CB) (3NB,lPB) (5CB) (5NB)
Blend 87 1839 50 2184 - ~- -
(5CB) (5NB)(5CB) (5NB) ;~
Ex. 14 Sterling
Control 40 2401 28 2565
(5CB) (5NB)(5CB) (5NB)
Blend 98 2030 56 2162
(5CB) (5NB)(5CB) (4NB)
Ex. 15 WP-Med. Screw
Control 33 2374 30 2470
(5CB) (5NB) (5CB) (3NB,lCB)
Blend 528 206253 2253
30(2NB,3CB) (5NB)(5CB) (5NB) -
Ex. 3 WP-Hard Screw
Control 32 241724 1712 ~ -~
(5CB) (5NB)(5CB) (2NB,3CB)
3581end 1198 191954 2200
(5NB) (5NB)(5CB) (5NB)
The results in Table III clearly show that single
screw extruders do not provide the necessary shear to
prepare blends with high notched impact strength as
compared to twin screw extruders. (The data from Example
3 is included for comparison purposes.) It is important
to note that while the "medium" screw design gives less
shearing action than the "hard" screw design, the
"medium" screw design gives more shearing action than a ~-
"
W O 94/06864 PC~r/US93/08132
2~ 720
- 25 ~
single screw extruder. However, the results also
indicate that twin screw extruders do not necessarily ~ `~
provide the proper amount of shear unless the "hard"
screw design is employed.
EXAMPLE 16-20
The PET of Example 1 was dried at 150C. for 16
hours in desiccant air with a dew point S-29C. -~
Ionomer A was dried at 60C. for 16 hours in desiccant
air with a dew point S-29C. The PET and Ionomer A were
pellet blended in a polyethylene bag such that the
concentration of Ionomer A was 20 weight percent.
Samples containing only PET were used as control
examples. The blend and control sample were run on the
same extruder and injection molded on the Boy 22-S ~ ~p ~-
injection molding machine. The blend and control sample
were annealed and crystallized at 150C. in a forced air
oven for a period of zero, two, four, six, and eight ~ ~ -
minutes, respectively. The test results are summarized ;~
in Table IV. Unannealed bars of the PET control and the
blend are included in Table IV for comparison purposes.
;:':
, .., ., .
W094/06864 PCT/US93/08132
.~ .
~ h
-: .
- 26 -
, .
TABLE IV . . ~ :
ANNEALING -~
TINE AT IZOD IMPACT STRENGTH (J~m)
150C. Notched Unnotched Notched Unnotched
S EXAMPLE (min.)(23C.) (230C.l(-40C.l (-40C.l
Ex. 16 '~
Control 0 28 2475 30 3355
(5CB) (5NB)(5CB) (4NB)
Blend 0 1203 2226 56 2783 ' '~
(5N8) (5NB)(5CB) (5NB) '~'~''''''"
Ex. 17 , -8~
Control 2 31 287g 29 1685 ~~''~''''' '
(5CB) (5NB)(SCB) (lNB,4CB) `~
Blend 2 109 2131 66 1866
(lPB,4CB) (5NB) (5CB) (3NB,lCB)
Ex. 18 ' -~
Control 4 30 2995 28 2300
(5CB) (5NB)(SCB) (2NB,3CB) '~
Blend 4 93 2465 90 2592
(5CB) (5NB) (5CB) (5NB)
Ex. 19 '~
Control 6 28 3254 36 2602 ~'~'"'""-'';'~'
(5CB) (5NB)(5CB) (lNB,4CB)
Blend 6 92 2560 73 1908
(5CB) (5NB)(5CB) (3NB,lCB) ~ '
Ex. 20
Control 8 23 2889 33 1373
(5CB) (3NB,lCB) (5CB) (lNB,4CB) ''
Blend 891 2518 82 2374
(5CB) (5NB) (5CB) (SNB)"~ '
The results in Table IV clearly show that the ';~
blends Or the present invention, even in a highly
crystalline form, have better impact strength than "' '~
crystalline PET. As the annealing time at 150C. is
increased from-2 to 8 minutes the crystallinity of the
polymers increases as determined by density gradient `~;-';' '
tube measurements. After the maximum crystallization
time of 8 minutes is obtained, the PET~ionomer blend
still retains a notched Izod impact strength at 23C. of
91 J~m compared to 23 J~m for the similarly treated PET
~ ,', . ' .,`. ~.''' .
W 0 94/06864 PC~r/US93/08132 ~ ~
2~i~272~
27
control. This is a 300% increase in impact strength.
Low temperature notched Izod impact strength determined -
at -40C. also shows improvement over the annealed
control. For example, the PET~ionomer blend still
5 retains a notched Izod impact strength at 23c. of 82
J~m compared to 33 J~m for the similarly treated PET
control. It is important to note that even after 8
minutes of annealing, the notched Izod impact strength
is higher than the uncrystallized PET control which is
30 J~m at -40C.
In addition, the unnotched Izod impact strength of
the blend at -40C. after annealing for 8 minutes also
shows significantly improved ductile strength, 5NB, as
compared to the PET control which had a value of 4CB,lNB -
indicating mostly brittle failure. ~-
,~
EXAMPLE 21
The PET of Example 1 was dried at 150C. for 16
hours in desiccant air with a dew point 5-29C.
Ionomer A was dried at 60C. for 16 hours in desiccant
air with a dew point S-29C. The PET and Ionomer A were
pellet blended in a polyethylene bag such that the
concentration of Ionomer A was 20 weight percent. The
PET~Ionomer A blend was placed in the hopper, under dry
N2, of a Werner and Pfleiderer ZSK-30mm corotating,
intermeshing twin screw extruder having a screw length
of 1061 mm wherein 266 mm of the screw length contains
kneading blocks and left-handed blocks to provide high
shear. The blend was melt processed at 260C. under
high shear conditions, stranded and pelletized. ~ -
The pelletized blend was dried at 100C. for 8
hours in desiccant air with a dew point S-29C. and
injection molded on a Toyo T9OG injection molding
machine using a melt temperature of 265C. and a mold
' ' ' ~ ' ' " '
W094/06864 PCT/US93/08132
~4~ 28 -
temperature of 230c. to provide amorphous test
specimens.
The same high impact strength was obtained with
this blend as was obtained from the identical blend of
Example 4 which was made on the Werner and Pfleiderer
ZSK-28mm corotating, intermeshing twin screw extruder ;
and molded on the Boy 22S injection molding machine. ~-
EXAMPLES 22-30
The Werner and Pfleiderer ZSK-28mm twin screw
extruder has a torque meter. The effect of torque over ~ ~-
a range of 67.8 Joules to 101.7 Joules (600in-lb to -~
900in-lb) was evaluated. The torque was adjusted by
changing the throughput rate of the polymer. A higher
throughput rate of polymer resulted in higher torque.
Torque was also adjusted by changing the extruder RPM.
Example 22 contained the PET of Example 1.
Example 22 was not passed through an extruder but was ~ -
injection molded, thus no torque was applied. Examples
23 to 30 were passed through an extruder and injection
molded. Example 23 contained the PET of Example 1 and
101.7 Joules of torque wa8 applied. Example 24 was a
PET~Ionomer A blend such that the concentration of
Ionomer A was 15 weight percent, and 101.7 Joules of
torque was applied. Example 25 contained the PET of
Example 1 and 90.4 Joules of torque was applied.
Example 26 was a PE?~Ionomer A blend such that the
concentration of Ionomer A was 15 weight percent, and
90.4 Joules of torque was applied. Example 27 contained -
the PET of Example 1 and 79.1 Joules of torque was
applied. Example 28 was a PET~Ionomer A blend such that
the concentration of Ionomer A was 15 weight percent, ;;
and 79.1 Joules of torque was applied. Example 29
contained the PET of Example 1 and 67.8 Joules of torque
3S was applied. Example 30 was a PET~Ionomer A blend such ; ~ `
.,~',... `: :', .~
W094/06864 PCT/US93/08132
2~272`0
.
,. - ~ ~;
- 29 -
that the concentration of Ionomer A was 15 weight
percent, and 67.8 Joules of torque was applied.
TABLE V
Effect of Torque on Izod Impact Strength
TEST Ex. 22 Ex. 23 Ex. 24 Ex. 2S Ex. 26 -~
TORQUE (J) 0 101.7 101.7 90.4 90.4
DENSITY
Before Nolding 1.399 1.378 1.280 1.377 1.296
After Nolding 1.337 1.335 1.267 1.338 1.268
HEAT DEFLECTION TEMP.(C.)
0 0.45 MPa 70 69 66 71 67 ` `-
~ 1.82 MPa 61 63 60 63 S9
I.V. (dl~g)
Before Molding 0.692 0.643 0.654 0.642 0.664
After Molding 0.629 0.641 0.573 0.621 0.544
FLEXURAL STRENGTH
(NPa) 74.62 74.96 52.16 74.62 52.92 -~
FLEXVRAL MODULUS
(MPa) 2432 2391 17502439 1771
BREAX ELONGATION
(%) 450 313 376 422 344
TENSILÉ STRENGTH .;.~.. --.. -./
(MPa)81.564.0 65.9 79.3 60.8 ~-- -, " .'.!,`
YIELD STRENGTH `~
(MPa) 56.2 56.9 43.8 56.4 44.6 `
BREAX STRENGTH
(MPa) 81.5 64.0 65.9 79.3 60.8
MOLD SHR.(%) 0.270 0.250 0.480 0.280 0.460 ;, ~-
23C NOTCHED42.238.4 1127 28.8 584.7 ~ ` :
(J~m) SCB 5CB SNB 5CB 3CB,2NB
23C UNNOTCHED 2852 2638 2273 2739 2202
(J~m) 5NB 5NB 5NB 5NB 5NB ~ ;
-40C NOTCHED27.826.2 44.3 26.7 46.5
(J~m) 5CB 5CB 5CB 5CB 5CB ; ~`
-40C UNNOTCHED 3278 2754 2735 2682 2806
(J~m) 5NB3CB,2NB 5NB 2CB,3NB 5NB
ZINC (%) 0 0 0.42 0 0.42
.--. - :...
W094/06864 PCT/VS93/08132 ~
~4~ 30 - ;~
TABLE V (continued)
Effect of ~orque on Izod Impact Strength i
Ex. 27 Ex. 28 Ex. 29 Ex. 30
TORQUE (J) 79.1 79.1 67.8 67.8
DENSITY - -
Before Molding 1.3751.292 1.373 1.288 ~ ;
After Molding 1.337 1.268 1.337 1.268
HDT (C.)
0 0.45 MPa 66 64 66 64
Q 1.82 MPa 66 60 60 57 ~ -
I.V. (dl~g)
Before Molding 0.6500.648 0.616 0.626
After Molding 0.6210.553 0.558 0.549
FLEXURAL STRENGTH
(MPa) 74.8 52.6 74.0 52.7
FLEXURAL MODULUS
(MPa) 2418 1785 2363 1791 ~-
BREAK ELONGATION
(%) 405 365 523 381
TENSILE STRENGTH ;-
(MPa) 76.5 63.4 78.865.8
YIELD STRENGTH
(MPa) 56.2 43.9 56.343 9
BREAK STRENGTH
(MPa) 60.8 76.5 63.765.8
MOLD SHR.(%) 0.280 0.500 0.200 0.480
23C NOTCHED 30.4 940.9 36.8552.7
(J~m) 5CB lCB,3NB 5CB3CB,2NB
23C UNNOTCHED 2740.5 2308.5 2390.7 2176.1
(J~m) SNB 5NB 5NB5NB
-40C NOTCHED 24.0 40.6 25.6 41.7 -~ ~
(J~m) SCB 5CB 5CB 5CB - i -
-40C UNNOTCHED 3375 2698 2494 2841
(J~m) 5NB 5NB lCB,3NB 5NB
ZINC (t) O 0.43 0 0.43
~ -i
The results in Table V indicate that higher torque
results in more shear being applied to the sample. The -
data also indicates that the blends of PET~Ionomer A
display significantly more impact resistance than the
control ~amples of PET. Moreover, the highest impact
properties are achieved with the blends at the maximum ~ ".!,,~
torque. Notched and unnotched impact strength continued
... ~ ~ ......
W O 94/06864 PC~r/U593/08132
21~2 ;72~
~:
- 31 -
to increase for the blends as the torque was increased
from 67.8 Joules to 101.7 Joules.
EXAMPLE 31
The PET of Example 1 was dried at 150C. for 16
hours in desiccant air with a dew point S-29C.
Ionomer C was dried at 60C. for 16 hours in desiccant
air with a dew point s-29C. The PET and Ionomer C were
pellet blended in a polyethylene bag such that the
concentration of Ionomer C was 5 weight percent. The
PET~Ionomer C blend was placed in the hopper, under dry
~2, of a Werner and Pfleiderer ZSK--28mm corotating,
intermeshing twin screw extruder having the "hard" screw
design. The blend was melt processed at 260C. under
high shear conditions, stranded and pelletized.
The pelletized blend was dried at 100C. for 8
hours in desiccant air with a dew point S-29C. and
injection molded on a Boy 22S injection molding machine
using a melt temperature of 260C. and a mold
temperature of 23C. to provide amorphous test
specimens. The impact properties of the blend are
summarized in Table VI. The impact properties of
Example 1 which is the PET control is provided for
comparison purposes.
$~5 32-34
The procedure of Example 31 was followed except : :-
that the concentration of Ionomer C in the PET blend was
changed to provide Ionomer C concentrations of 10, 15
and 20 weight percent, respectively. The effect of the
zinc ionomer concentrations in PET are summarized in
; Table VI.
W O 94/06864 PC~r/US93/D8132 ~ ~ ~
~4~ 32 ~
EXAMPLES 35-38
The procedure of Example 2 was followed except that
Ionomer C was substituted with Ionomer D. The
concentration of Ionomer D in the PET blends was 5, 10,
15 and 20 weight percent, respectively. The results are
summarized in Table VI.
-' '~"~, '
TABLE VI
Impact Strength of Zinc and Sodium Copolymer Ionomers
IONOMER IONOMER IZOD IMPACT STRENGTH (J~m)
C D Notched Unnotched Notched Unnotched
EXAMPLE (wt%~ (wt~) r23C.) (23C.) (-40C.) (-40C.
Ex. 10 0 32 2362 30 1949
lS (5CB) (5NB) (5CB) (3NB,2CB) ;~
Ex. 31 5 0 44 1720 37 2076 ~ -
(5CB) (5NB) (5CB) (5NB)
Ex. 32 10 0 56 1837 41 2173
(5CB) (5NB) (5CB) (5NB) ~ -
Ex. 33 15 0 119 2050 52 2452
(5CB) (5NB) (5CB) (5NB)
Ex. 34 20 0 1050 2046 61 2102
(4NB) (5NB) (SCB) (5NB)
Ex. 35 0 S 30 2590 28 2811 ~- `
(SCB) (SNB) (SCB) (5NB)
Ex. 36 0 10 38 2562 34 2728
(5CB) (SNB) (SCB) (SNB)
Ex. 37 0 lS 47 2232 41 2419 - '-
(SCB) (SNB) (5CB) (5NB)
! I Ex. 38 0 20 43 2443 39 2303 ,~
(5CB) (5NB) (5CB) (5NB)
The data in Table VI indicates that significant
increases in impact strength at 23~C. and -40C. are ;
achieved with the PET~Ionomer C blends wherein the acid
component is neutralized with zinc exhibit as compared ~
:
- .
W O 94/06864 PC~r/US93/08132
2~ ~27~
- 33 ~
to PET~Ionomer D blends wherein the acid component is
neutralized with some other ion such as sodium.
Moreover, the mode of impact failure for the blends
utilizing zinc was ductile as opposed to brittle for the
blends utilizing sodium. ~ - ;
Many variations will suggest themselves to those
skilled in this art in light of the above detailed
description. All such obvious modifications are within
the full intended scope of the appended claims.
,'~: i
