TITLE: GRAFT COPOLYMERS AND BLENDS THEREOF WITH POLYOLEFINS
European Patent Application EP0335649 A3

ABSTRACT:
Abstract of EP0335649
A novel graft copolymer capable of imparting to a polyolefin when
blended therewith a good balance of tensile modulus, sag resistance and
melt viscosity, is a polyolefin trunk having a, preferably relatively
high weight-average molecular weight, methacrylate polymer chain
grafted thereto. The graft copolymer is formed by dissolving a
non-polar polyolefin in an inert hydrocarbon solvent, and, while
stirring the mixture, adding methacrylate monomer together with
initiator to produce a constant, low concentration of radicals, and
covalently graft a polymer chain, preferably of relatively high
molecular weight, to the polyolefin backbone. The graft copolymer can
be separated from the solvent, by volatilizing the solvent, for example
in a devolatilizing extruder, and pelletised or extruded or otherwise
shaped into a desired shape such as a sheet, tube or the like. This
graft copolymer can be blended with a polyolefin matrix to improve its
physical properties in the melt, upon cooling, and in the solid state,
and is useful in cast and oriented films, solid extruded rod and
profile, foamed rod, profile and sheet and blown bottles. The graft
copolymer can also be used to improve compatibility between polymers in
a wide range of polymer blends.

INVENTORS:
Ilenda, Casmir Stanislaus (US)
Work, William James (US)
Graham, Roger Kenneth (US)
Bortnick, Newman (US)

APPLICATION NUMBER: EP19890303029
PUBLICATION DATE: 07/10/1991
FILING DATE: 03/28/1989

ASSIGNEE: ROHM & HAAS (US)
INTERNATIONAL CLASSES: C08F255/00; C08F255/02; C08L23/02; C08L23/10; C08L51/00; C08L51/06;
C08L25/04; C08L27/04; C08L67/00; C08L77/00; (IPC1-7): C08F255/00;
C08L57/00
EUROPEAN CLASSES: C08F255/00; C08F255/00+220/18; C08F255/02; C08L23/02+B5; C08L23/10+B5;
C08L51/06+B2; C08L51/06+B4

CLAIMS:
1. A graft copolymer suitable for improving the tensile modulus and sag
resistance of a polyolefin when blended therewith, the copolymer
comprising: (a) a non-polar polyolefin trunk comprising units of one or
more of ethylene, propylene, butylene, and 4-methylpentene, said trunk
further optionally containing a minor amount of units of one or more of
the following: 1-alkenes, vinyl esters, vinyl chloride, acrylic and
methacrylic acids and esters thereof; and (b) at least one
poly(methacrylate) chain, grafted with a covalent bond to said trunk,
said chain being present in a weight ratio to said trunk of from 1:9 to
4:1, said chain comprising at least 80% by weight units of methacrylic
ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl,
substituted alkyl, substituted aryl, or substituted alkaryl, and
optionally up to 20% by weight of units of other monomer comprising
styrenic, other acrylic or other monoethylenically unsaturated monomer
copolymerizable with the methacrylic ester or, in an amount of up to
5%, maleic and/or itaconic acid or anhydride.
2. A copolymer as claimed in claim 1 wherein the methacrylate chain has
a weight average molecular weight of 20,000 to 200,000, preferably
30,000 to 150,000.
3. A copolymer as claimed in claim 1 or 2 wherein the trunk has a
weight average molecular weight of 50,000 to 1,000,000, preferably
100,000 to 400,000.
4. A copolymer as claimed in claim 1, 2, or 3, wherein the polyolefin
trunk comprises polypropylene and/or the methacrylate chain comprises
methyl methacrylate units.
5. A blend of polyolefin with (a) graft copolymer of any preceding
claim, and, optionally (b) ungrafted methacrylate polymer having a
monomer composition as defined in Claim 1(b) and having a
weight-average molecular weight greater than 20,000.
6. A polymer blend as claimed in claim 5 which is (a) a concentrate
containing from 5 to 50% of the graft copolymer, based on the weight of
the blend or (b) a composition containing at least 0.2% but less than
5% of said graft copolymer and, optionally, 0.001 to 0.05% alkyl
polysulfide, preferably di-t-dodecyl disulfide, by weight based on the
total polymer composition, or, optionally, 0.001 to 0.1% tris
(polyalkylhydroxybenzyl)-s-triazinetrione, preferably tris-
(4-t-butyl-3-hydroxy-2, 6-dimethylbenzyl)-s-triazine (1H,3H,5H)-trione,
by weight based on the total polymer composition, and/or optionally a
blowing agent, preferably one which liberates nitrogen at a temperature
of 200 to 230 DEG C and preferably in an amount of 1 to 2% by weight
based on the total polymer composition.
7. A polymer blend as claimed in claim 5 or 6 wherein the polyolefin
trunk comprises poly (propylene), poly(ethylene), poly(butylene) and/or
a copolymer of at least 80% propylene with ethylene.
8. A polymer blend as claimed in claim 5, 6 or 7 comprising the
ungrafted methacrylate polymer in an amount of at least 80% of the
polymer blend.
9. A process for preparing a graft copolymer comprising the steps of:
(a) introducing inert solvent and non-polar polyolefin comprising units
of one or more of propylene, ethylene, butylene, 4-methylpentene and,
optionally, minor amounts of units of one or more of the following:
1-alkenes, vinyl esters, vinyl chloride, acrylic and methacrylic acids
and esters thereof, into a reaction vessel; (b) heating the mixture so
formed to a temperature at which the polyolefin dissolves; (c) adding,
with agitation, monomer capable of forming a chain as defined in Claim
1(b); (d) adding to the mixture so formed initiator which produces a
low and constant radical flux for a time sufficient to produce
methacrylate chain polymer covalently bonded to the polyolefin; and (e)
removing the solvent.
10. A process according to Claim 9 as applied to the production of
graft copolymer or blend according to any of Claims 2 to 7.
11. A process according to Claim 9 or 10 wherein the initiator
comprises oil soluble, thermal free radical initiator which has a half
life of one hour at a temperature of 60 DEG C to 200 DEG C, preferably
90 to 170 DEG C.
12. A process as claimed in claim 9, 10 or 11 wherein the constant
radical flux at the temperature in the reaction vessel is from 0.00001
to 0.0005 equivalents of radicals per minute.
13. A process as claimed in any of Claims 9 to 12 wherein the solvent,
which is preferably a hydrocarbon solvent, is removed in a
devolatilizing extruder.
14. A polymer blend as claimed in any one of Claims 5 to 8 in the form
of a shaped article.
15. A shaped article as claimed in claim 14 which comprises an
extruded, calendered or moulded, optionally foamed, blend as claimed in
any of Claims 5 to 8 or pellets of said blend.
16. An article as claimed in Claim 15 comprising ungrafted
polypropylene in an amount by weight of the total polymer content, of
at least 80%.
17. A shaped article as claimed in Claim 15 or 16 which is a fibre,
sheet, film, other solid profile or a hollow tube, formed by extrusion,
or a hollow container formed by moulding, preferably extrusion blow
moulding or injection blow moulding.
18. A film or fibre as claimed in Claim 17 of which the polymer is
orientated, preferably monoaxially orientated or, in the case of a
film, biaxially orientated.
19. A process for improving the tensile modulus and/or sag resistance
of polyolefin which comprises blending therewith a concentrate as
claimed in any of Claims 6 to 8 preferably to yield a product having a
weight ratio of at least 80 parts of polyolefin to 20 parts of graft
copolymer.
20. A process as claimed in Claim 19 wherein the blending is carried
out at a temperature of at least 150 DEG C and alkyl polysulfide,
preferably di-t-dodecyl sulfide in an amount of 0.001 to 0.05% by
weight of the total mixture, has previously been incorporated into the
mixture for blending.
21. A process as claimed in Claim 19 or 20 wherein the polyolefin
comprises polyethylene, polypropylene, polybutylene or a
polyethylene/polypropylene or polypropylene/polybutylene mixture.
22. A blend of one or more polar polymers with one or more non-polar
polymers including, as a compatibiliser, graft copolymer as claimed in
any of Claims 1 to 4.
23. A blend as claimed in Claim 22 wherein the non-polar polymer
comprises polyolefin preferably polypropylene, and/or polyethylene,
especially high density polyethylene, and/or ethylenevinylacetate
polymer, and/or ethylene/propylene/non-conjugated diene terpolymer and
the polar polymer comprises one or more of the following: acrylic
polymers, styrene-acrylonitrile polymers, ethylene-vinyl alcohol
polymers, polyamides, polyesters especially poly(ethylene
terephthalate), polycarbonates, poly(vinyl chloride)
acrylonitrile-butadiene-styrene polymers, poly(vinylidene chloride),
blends of polyester with polycarbonate and blends of poly(vinyl
chloride) with polyester.
24. A blend as claimed in claim 22 or 23 wherein the weight ratio of
polar polymers to non-polar polymers is from 95:5 to 5:95, preferably
from 80:20 to 20:80.
25. A blend as claimed in any of claims 22 to 24 wherein the graft
polymer is present in an amount of 0.2 to 10, preferably 0.5 to 5,
parts by weight per 100 parts by weight of polar, non-polar and graft
polymer.
26. A process for improving the mutual compatibility of polymers of
different polar levels which comprises blending therewith 0.2 to 10% by
weight, of the total polymer mixture, of graft polymer as claimed in
any of Claims 1 to 4.

DESCRIPTION:
With 5% of the graft copolymer of Ex. 69 present, the bubble of Example
96 was stabilized, the frostline levelled, and the frostline moved
closer to the die. Both 108- and 165-mm, lay-flat films were produced.
Although some fluctuation in die pressure was noted when forming the
latter film, it had the most stable bubble.
This increase in bubble stability was also observed with the 1% and 5%
dry blends of Examples 97 and 98. No significant differences in film
appearance was observed between the 5% precompounded blends and the dry
blends.
The modified films had decreased film see-through clarity. Contact
clarity remained unchanged. No difference in edge-roll color was
observed between modified and unmodified film.
The "openability" of neat and modified film was tested. Although a very
qualitative test (the collapsed film is snapped between the fingers and
one feels how well it opens), no difference between the unmodified and

modified resins was observed. EXAMPLES 99 - 104
The experiments illustrate the use of the graft polymer of the present
invention in producing polypropylene cast film. A single-screw
extruder, manufactured by Killion Co., was equipped with a 3.81-cm
screw of 24/1 length/diameter ratio, a 20.3-cm x 0.635-mm cast film
die, a chill roll and a torque winder for the film, was utilized. The
extruder melt temperature was 226 DEG C. The melt was extruded through
the die and onto the chill rolls, the take-up speed being adjusted to
produce film of various thicknesses. Film thicknesses was measured, as
was "neck-in", an undesirable shrinkage of width. Film stiffness and
edge roll color were measured qualitatively.
Film thicknesses were adjusted increasing line speed of the torque
winder and lowering the extruder output by reducing screw speed.
Columns=3 Head Col 1: Film of Example Head Col 2: Starting Material
Head Col 3: Form Ex. 99Ex. 74Unmodified Ex. 100Ex. 75Pre-blend; 5% GCP
Ex. 101Ex. 74 and Ex. 69Dry blend; 5% GCP Ex. 102Ex. 81Unmodified Ex.
103Ex. 82Pre-blend; 1% GCP Ex. 104Ex. 83Pre-blend; 5% GCP
GCP = graft copolymer of Example 69
Films of the composition of Example 99 were uniform and consistent at
thicknesses of from 0.25 mm to below 2.5 mm. Example 100 produced
acceptable film of improved edge color and with less film neck-in.
Example 101 also produced less neck-in, but did not improve edge color.
Both modified versions yielded stiffer films at equivalent thickness
versus the control, allowing the film to be wound more easily. The
opacity of the film increased with the addition of the graft polymer.
With Examples 102 to 104, the neck-in differences were not noted when
the graft copolymer additive was present. The films at both 1 and 5
weight percent graft copolymer were stiffer than the unmodified control

(Examples 103 and 104 versus Example 102). EXAMPLE 105
This example illustrates that biaxially oriented film can be prepared
from a polypropylene resin containing 5% of the polypropylene/methyl
methacrylate graft copolymer. Under the limited conditions tested,
which were optimum for the unmodified resin, no distinct advantage
could be seen for the additive. At identical extrusion and MDO (machine
direction orientation) conditions, the modified resins could not
achieve and maintain the line speeds possible with the unmodified resin
during the TDO (transverse direction orientation).
The control resin was Example 81, mfr=2.2, high-clarity homopolymer
marketed for film use. Pre-compounded resins were Examples 82 and 83,
containing respectively 1% and 5% of the graft copolymer of Example 69
(under the extrusion conditions, a dry blend of 5 parts graft copolymer
of Ex. 69 with the matrix resin of Example 81 gave very poor
dispersion, leading to many gels and frequent film breaks). The blends
were processed in a 50.8-mm, Davis-Standard single-screw extruder which
conveyed the melt through a 0.48-meter die and onto a 1.02-meter
casting roll. An air knife was used to blow the extrudate onto the
casting roll. The casting roll rotated through a water bath to
completely quench the sheet.
The sheet then was conveyed into the MDO, supplied by Marshall and
Williams Co., Providence, RI, and comprising a series of heated nip
rolls, moving at speeds which cause monoaxial orientation.
After the MDO, the film passed through a slitter to cut the film to the
proper width and then onto a winder. These rolls were used to feed the
film into the TDO, which is an oven with three heating zones, rolls for
conveying the film forward, and clamps to grip and laterally expand the
film.
The film from Example 81 (unmodified resin) was drawn both 4.75:1 and
5.0:1 in the MDO, and could be drawn 9:1 in the TDO. The unmodified
4.75:1 MDO resin could maintain a TDO line speed of 8.69 meters/minute;
the unmodified 5.0:1 MDO resin could maintain a line speed of 6.85
meters/minute
The film from Example 82 (1% graft copolymer) could receive a MDO of
4.75:1 and TDO of 9:1 and maintain a 6.85-meters/minute TDO line speed.
Frequent film breakage was encountered at higher MDO and higher line
speeds. This biaxially oriented film appeared to be slightly more
opaque than the biaxially oriented film from Example 80. No difference
between the edge roll colors of film from Examples 81 and 82 was
observed for MDO film.
The films from Example 83 received MDO'S of 4.75:1, 5.0:1, and 5.25:1
at a TDO of 9:1. The best film was obtained with a line speed of 6.85
meters/minute and with the lowest MDO; tearing would occur under more
stressed conditions. Films from Example 83 were noticeably more opaque
and the frost line appeared sooner than with the control film of

Example 81. EXAMPLE 106
This example illustrates a profile extrusion trial using polypropylene
modified with a graft copolymer of the present invention. A
single-screw extruder was equipped with a die and appropriate cooling,
pulling, and sizing equipment to form a profile in the shape of a solid
rod with horizontal flanges. The rod diameter was 4.83 cm., flanges
2.67 cm. (extended beyond rod), and flange thickness 1 .52 cm. With
unmodified resin (Tenite 4E11 copolymer, Eastman Chemical, as described
in Example 78), symmetry was difficult to maintain in the profile
without sag or distortion. When blends of Example 79 and 80 (1 and 5%
graft copolymer, respectively) were employed, the maintenance of shape

was improved. EXAMPLE 107
This example illustrates the use of a graft copolymer blend of the
present invention in the modification of polypropylene to produce
improved plastic tubing. The polymers used were the unmodified resins
and the resins compounded with 5% of the graft copolymer of Ex. 69, as
described in Examples 72 to 77.
A 25.4-mm, single-screw Killion Extruder (Killion Extruders Co., Cedar
Grove, NJ) was equipped with a screw of 24/1 length/diameter ratio, a
tubing die with an outer die diameter of 11.4 mm. and a variable inner
diameter, leading to a 0.25-meter-long water trough for cooling, an air
wipe, and a puller and cutter. Conditions and observations are shown in
Table XXVIII below. Ovality is the ratio of smallest outer diameter to
largest outer diameter, as measured by calipers; a value of 1 means the
tube is uniformly round.
When tubing of good ovality was produced from the unmodified resin, the
major effect of the additive was improvement in tubing stiffness. With
the resin of Example 72, where ovality was difficult to control at
acceptable output rates, the modified resin (Example 73) improved
ovality as well as stiffness.
Columns=5 Tubing Prepared from Polypropylene and Modified Polypropylene
Head Col 1: Polymer Head Col 2: Melt Temperature, DEG C Head Col 3:
Melt Pressure, kPa( a ) Head Col 4: Inner Diameter mm (set) Head Col 5:
Ovality Ex. 7221782708.10.75 Ex. 7321468908.1 0.88 ( b ) Ex.
7418596508.10.97 Ex. 7519768908.1 ( c ) 0.77 Ex. 7618468908.1 ( d )
0.92 Ex. 7718082708.1 ( d ) 0.90 ( b , e ) (a) Extrusion rate
equivalent for paired unmodified and modified resin. (b) Modified
extrudate tube stiffer. (c) Higher melt temperature required to avoid
"sharkskin" on tubing. (d) With this higher mfr resin, reduced melt
temperature and higher puller speed led to tubing of lower outer
diameter.. (e) Modified tubing more opaque.

EXAMPLES 108 - 109
This example illustrates the preparation of pre-compounded blends
containing talc. The talc used is a white, soft, platy talc of particle
size less than 40 mu m; known as Cantal MM-45-90 (Canada Talc
Industries Limited, Madoc, Ontario). It was used at the 20% level. The
polypropylene used was a homopolymer of mfr=4, known as Himont 6523.
The graft copolymer was incorporated at the 5-weight-percent level and
was the graft copolymer of Example 69. The compounding/preparation of
these samples was carried out on a 30-mm Werner-Pfleiderer co-rotating,
twin-screw extruder.
The materials were tumble blended prior to the compounding.
Columns=4 Head Col 1: Blend Head Col 2: % Talc Head Col 3: Modifier
Head Col 4: Matrix Polymer Example 108 (control)20 Cantal----- 80%
Himont 6523 Example 10920 Cantal5% Example 75% Himont 6523
The preparative conditions for the blends are given in Table XXIX. The
extruder was operated at 200 rpm, with no vacuum, at rates of 4.5-4.6
kg/hour, and 85-86% torque.
Columns=3 Head Col 1 AL=L: Zone Head Col 2 to 3 AL=L: Extruder Zone
Settings, DEG C SubHead Col 1: SubHead Col 2: Example 108 SubHead Col
3: Example 109 SubHead Col 4: SubHead Col 5: set point/actual SubHead
Col 6: set point/actual Z-1125 / 148125 / 151 Z-2220 / 218220 / 219
Z-3230 / 228230 / 229 Z-4230 / 242230 / 241 Z-5240 / 239240 / 239
Z-6240 / 239240 / 239 Z-7240 / 242240 / 239 Z-8 (die)225 / 239225 / 239

Melt239243 EXAMPLES 110 - 112
These examples teach the injection molding of polypropylene of various
compositions and melt flow rates, the polypropylenes containing a graft
copolymer of the present invention. In two examples, a 20% loading of
platy talc is also present.
Polypropylene may be injection molded into useful objects by employing
a reciprocating-screw, injection-molding machine such as that of Arburg
Maschien Fabrik, Lossburg, Federal Republic of Germany, Model
221-51-250. In the preparation of test samples, the extruder is
equipped with an ASTM mold which forms the various test pieces. The
conditions chosen for molding were unchanged throughout the various
matrix and modified matrix polymers, and no difficulties in molding
were noted. Table XXX describes the blends which are molded; Table XXXI
teaches the molding conditions; Table XXXII reports modulus values,
Table XXXIII Dynatup impact data, and Table XXXIV heat distortion
temperature values for the modified polymers and their controls.
In the following list of injection-molded polymers and blends, all
samples contain 1 or 5 weight percent of the graft copolymer of Example
69. The polypropylene matrix resins are described in earlier examples;
HP is homopolymer, CP is copolymer, the number is the mfr value. The
blends with talc are described in Examples 108 and 109. All materials
were pre-blended in the melt, except where a dry blend from powder was
directly molded. (C) is an unmodified control; (CT) is a control with
talc, but no graft copolymer
All test methods were by ASTM standard methods: flexural modulus and
stress are by ASTM Standard Method D 790, heat distortion temperature
under load is by ASTM Standard Method D 648 and Dynatup impact is by
ASTM Standard Method D 3763.
Table XXX also includes the melt flow rates (mfr) for the unmodified
and pre-compounded blends. In most cases, the melt flow rate is
unchanged or slightly decreased in the presence of the graft copolymer,
so that the melt viscosity under these intermediate-shear conditions is
not extensively increased.
The melt flow rate is by ASTM Standard Method D-1238, condition L (230
DEG C., 298.2 kPa) and has units of grams extruded/10 minutes.
Columns=6 Head Col 1: Example Head Col 2: Matrix Head Col 3: Graft, %
Head Col 4: Talc, % Head Col 5: Dry-Blend? Head Col 6:
mfr 74 (C)HP, 4------4.40, 4.06 75HP, 45----6.07 110HP, 45--YES 108
(CT)HP, 4--20-- 109HP, 4520-- 76 (C)CP, 4------4.47 77CP, 45----3.75
111CP, 45--YES 72 (C)CP, 2------2.37 73CP, 25----2.02 112CP,
25--YES 78 (C)CP------2.92 79CP1----2.04 80CP5----2.12 81
(C)CP------2.33 82CP1----3.81 83CP5----2.16
Columns=4 SubHead Col 1: Injection Molding Conditions for Propylene
Head Col 1 to 2 AL=L: Cylinder temperatures, DEG C Head Col 3 to 4
AL=L: (setting/measured) Feed-216/216Metering-216/216
Compression-216/216Nozzle216/216 SubHead Col 2: Mold Temperatures, DEG
C Stationary-49/49Moveable-49/49 SubHead Col 3:
Cycle time, seconds Injection forward-14Mold Open-0.5 Cure-14Total
Cycle-0.5 Mold Closed-1.2 SubHead Col 4: Machine readings: Screw speed
(rpm)- 400 Back pressure (kPa)-172 Injection (1st stage)(kPa)- 861
The flexural modulus data from Table XXXII indicate the stiffening
effect of the graft copolymer. Results are in megapascals (MPa).
Columns=3 Head Col 1: Example Head Col 2: FLEXURAL MODULUS MPa Head Col
3: STRESS (at max) MPa 74 (C)1470.643.8 751744.447.5 1101783.146.9 108
(CT)2768.052.0 1092867.054.5
Table XXXIII summarizes Dynatup impact data (in Joules) at various
temperatures for the blends and controls tested. The data indicate, in
general, slightly improved impact for the pre-blended materials, a
deterioration in impact strength on molding dry blends of graft
copolymer and matrix polymer, and an increase in impact strength for
the talc-modified blend also containing the graft copolymer.
Columns=6 Head Col 1 to 2 AL=L: Example Head Col 3 to 6:
Dynatup Impact (joules) at Test Temperature, DEG C SubHead Col 1:
SubHead Col 2: SubHead Col 3: 23 SubHead Col 4: 15 SubHead Col 5: 5
SubHead Col 6: -5 74(C)4.9+/-2.74.4+/-1.53.8+/-0.32.6+/-. 41
755.7+/-3.44.6+/-0.82.7+/-1.53.4+/-1.09
1103.4+/-1.12.0+/-0.51.9+/-1.01.5+/-. 41
108(CT)3.0+/-0.53.4+/-0.84.2+/-1.65.0+/-2.5
1091.9+/-0.54.1+/-2.34.8+/-1.85.0+/-2.
5 76(C)40.0+/-0.5 7743.9+/-0.4 11114.0+/-6.4 72(C)37.9+/-1.8
7343.1+/-10.3 11232.4+/-9.5 78(C)36.7+/-0.4 7936.3+/-1.1 8037.1+/-0.7
81 * (C)13.3+/-10.7----3.3+/-0.82.7+/-0.2
824.9+/-0.7----3.0+/-1.43.0+/-0.8 837.6+/-3.7----3.3+/-0.83.5+/-1.1 *
The large standard deviation at room temperature is suspect.
Table XXXIV presents heat distortion and hardness values for one
series. The modified polymer appears to exhibit a slightly higher heat
distortion temperature and hardness, although there are inconsistencies
noted. The Rockwell hardness values represent separate determinations
on two samples of the material from the indicated example.
Columns=6 Head Col 1 to 2: Example Head Col 3 to 4: Heat Deflection
Temperature at 2 DEG C/Minute at Head Col 5 to 6:
Rockwell Hardness "C" Scale SubHead Col 1: SubHead Col 2: SubHead Col
3: 411 kPa SubHead Col 4: 1645 kPa 74(C)110.961.058.4 56.5
75113.863.360.759.3 110117.368.757.946.9 108(CT)128.276.857.3 64.7
109124.781.965.463.7

EXAMPLE 113
This example illustrates the effect of the molecular weight of the
polypropylene trunk component of the graft copolymer on the sag
modification of polypropylenes of various molecular weights. Graft
copolymers were prepared from polypropylene of various melt flow rates.
All modifiers were prepared as in Example 58. The 35 mfr polypropylene
(Himont PD-701) was run at 65% solids. The 12 mfr polypropylene (Himont
Pro-fax 6323) was run at 60% solids. The 4 mfr polypropylene (Himont
Pro-fax 6523) and the 0.8 mfr polypropylene (Himont Pro-fax 6723) were
run at 55% solids. The molecular weights for the polypropylene base
resins, where known, are given in Table XXXV, below.
These were evaluated as melt strength improvers at 4% by weight in
several of these same polypropylenes. Standard mill and press
conditions were used for all blends, except the 0.8 mfr/0.8 mfr
polypropylene blends which were milled at 215 DEG C and pressed at 215
DEG C. Sag rates were measured by the standard procedures. The sag
slope at 190 DEG C is reported in Table XXXVI below.
Columns=4 MW-MFR Data for Polypropylene Base Resin Head Col 1:
Molecular-Weight Source Head Col 2 to 4: Weight-Average Molecular
Weight x 10<5> SubHead Col 1: SubHead Col 2: 12 mfr PP SubHead Col 3: 4
mfr PP SubHead Col 4: 0.8 mfr PP (a)34.37.1 (b)2.453.053.5,4.7 (c)0.27
* 0.45 * --
Source of Molecular-Weight Value: a) Supplier's data. b) Sheehan et al,
J. Appl. Polymer Sci., 8, 2359 (1964). c) Mays et al, ibid., 34, 2619
(1987). * These values are number-average molecular weight.
Columns=5 Sag Slope at 190 DEG C for Olefin Blends (min<-><1>) Head Col
1: modifier (4%) Head Col 2 to 5: polypropylene base resin (96%)
SubHead Col 1: SubHead Col 2: 35 mfr PP SubHead Col 3: 12 mfr PP
SubHead Col 4: 4 mfr PP SubHead Col 5: 0.8 mfr PP none1.60.520.250.099
35 mfr PP based1.80.520.23 0.074 12 mfr PP based1.20.410.034 < 0.02 4
mfr PP based1.00.160.022 < 0.02 0.8 mfr PP based0.640.160.031 << 0.02
In all cases except where a high-melt-flow base resin was modified with
a graft polymer having a trunk of high-flow-rate (low-molecular-weight)
polypropylene, sag improvement was observed. The molecular weight for
the resin of mfr=35 is not accurately known; it is believed to be made
by thermal/oxidative processing of a higher molecular weight resin.
Such a process would both lower the molecular weight and narrow the

originally broad molecular-weight distribution. EXAMPLE 114
This example illustrates the effectiveness of the graft copolymers of
the present invention as compatibilizing agents for polymers that are
otherwise poorly compatible. In this example a polyolefin, a polar
polymer, and the graft copolymer of the present invention were
compounded in an intermeshing, co-rotating, twin-screw extruder
(Baker-Perkins MPC/V 30) with a screw length-to-diameter ratio of 10:1.
The compounder was run at 200 rpm and temperatures were adjusted to
accommodate the polymers in the blend and achieve a good melt. The melt
temperature in the compounding zone is recorded in the second column of
the table. The melt was fed directly to a 38-mm, single-screw,
pelletizing extruder with a length-to-diameter ratio of 8:1. The melt
temperature in the transition zone between the compounding and the
pelletizing extruder is shown in column 3 of Table XXXVIII, below.
The melt was extruded into strands through a die, cooled in a water
bath, and cut into pellets.
Table XXXVII below summarizes the polymers which were used in the
blends of the present example, while Table XXXIX shows that the graft
copolymer has little effect upon the tensile strength of the unblended
polymers, that is, it does not act to a significant degree as a
toughening agent. In the subsequent tables, Tables XL and XLI,
improvement in tensile strength of the blended polymers indicates an
increase in compatibility of the blended polymers with one another in
the presence of the graft copolymers of the present invention.
Under the proper compounding conditions, an increase in compatibility
may also produce a decrease in the size of polymer domains in the
blend. Scanning electron microscopy confirms that in some of these
examples, significant domain-size reductions occur when the graft
copolymer is added. For example, the polypropylene domains average 2
micrometers in the 70 PMMA / 30 PP blend of example 114. The addition
of 5 phr compatibilizer reduced the domain size to 0.5 mu m. The
addition of 15 phr compatibilizer reduced the domain size to 0.43 mu m.
Although not all of the domain sizes were reduced, several others were
reduced by 10-30% by the addition of 5 phr compatibilizer. This is a
further suggestion that the compatibilizer is acting on the interface
of the polymer domains rather than on the individual polymers.
Table XLI summarizes the compatibilizing effect of the graft copolymers
upon the various polymer blends. EMI91.1 EMI92.1
Columns=3 Head Col 1: Head Col 2 to 3: melt temperatures ( DEG C)
SubHead Col 1: SubHead Col 2: compounder SubHead Col 3: transition
PMMA225-235210-220 SAN220-230210-220 EVOH205-225200-215
PA66260-275255-270 PET245-275245-255 PVC205-230190-215 PC250-290240-270
The pellets were dried and injection molded on a reciprocating-screw
injection molding machine (New Britain Model 75) into test specimens.
Columns=4 Effect of Compatibilizer on Polymer Tensile Strength Tensile
Strengths Shown in MegaPascals (MPa) Head Col 1: Polymer Head Col 2 to
4: compatibilizer concentration SubHead Col 1: SubHead Col 2: 0 phr
SubHead Col 3: 5 phr SubHead Col 4:
15 phr PMMA65.4464.7961.27 SAN71.9162.7455.89 EVOH68.7866.2163.78
PA6664.8264.6866.60 PET58.2659.3359.72 PVC45.2544.9745.22
PC62.6363.0563.70 HDPE22.5922.6624.14 PP33.0234.0333.95 EP4.795.505.84
LLDPE10.9111.8012.99 EVA8.648.678.17
EMI95.1 EMI96.1 EMI97.1 EMI98.1 Columns=6 Compatibilization Effect Head
Col 1: Head Col 2: HDPE Head Col 3: PP Head Col 4: EP Head Col 5: LLPDE
Head Col 6:
EVA PMMA++++++ <1> +++++++++ SAN++++++++++++++ EVOH+++++ <1> 00++
PA66+++++ <1> ++0 PET+++ <1> ++++++ PVC+++++++++++ <1> ++ PC+++++ <1>
++++
+++ - compatibilization at all three polyolefin-polar polymer ratios
(not necessarily at all compatibilizer levels)
++ - compatibilization at two of the three polyolefin-polar polymer
levels
+ - compatibilization at one of the two polyolefin-polar polymer levels
0 - no compatibilization seen at any polyolefin-polar polymer ratio, at
any compatibilizer level (1) - additional evidence for
compatibilization in the reduction of domain size by 10-80%

EXAMPLE 115
The compatibilizing effect on selected, additional polymer pairs was
evaluated in the following example. The blends were compounded, molded
and tested for tensile strength as previously described. The results in
Table XLIII again indicate that the compatibilizer has minimal or a
negative effect on the polar polymers, but a positive effect on the
polar/nonpolar polymer blends. A large tensile strength improvement is
seen for the ABS / PP blend. Smaller but significant improvements are
seen for the blends of PP with PA6 and with PC / PBT.
With the PS blends evaluated the effect was negligible.
Columns=6 Head Col 1: polar polymer Head Col 2: nonpolar polymer Head
Col 3 to 6: tensile strengths (MPa) SubHead Col 1: SubHead Col 2:
SubHead Col 3: polar polymer SubHead Col 4: polar polymer + 15 phr
graft copolymer SubHead Col 5: blend <1> SubHead Col 6: blend <1> + 15
phr graft copolymer PBTPP43.0245.1136.96 38.96 PA6PP56.1151.6743.50
47.04 PSPP45.2640.4538.88 37.36 PSHDPE45.2640.4536.48 33.76
ABSPP51.2552.2532.25 42.55 PC/PBTPP51.7751.7938.99 41.88 1 - blend in
all cases refers to 55 parts by weight polar polymer and 45 parts by
weight nonpolar polymer.
The effect of the graft copolymer on multi-component blends such as
those representative of commingled scrap polymers are shown in Table
XLIV. In all cases a significant increase in tensile strength is
observed when the compatibilizer is present.
Columns=8 Compatibilization of Multicomponent Blends Head Col 1 to 3
AL=L: Polar Polymers Head Col 4 to 6 AL=L: Nonpolar Polymers Head Col
7: Compatibilizer Head Col 8: Tensile Strength (MPa) SubHead Col 1: PS
SubHead Col 2: PET SubHead Col 3: PVC SubHead Col 4: HDPE SubHead Col
5: LLDPE SubHead Col 6:
PP 127533.533.59none16.27 127533.533.59517.67 127533.533.591521.77
128-353510none18.62 128-353510519.98 128-3535101522.16
12-6363610none17.06 12-6363610519.21 12-63636101521.91

EXAMPLE 116
This example further illustrates compatibilization of polymer blends
using graft copolymers of the present invention.
Blends of ethylene-vinyl alcohol copolymer (Kuraray EP-F101A),
polypropylene (Himont 6523) and graft copolymer were milled on a
7.62-cm X 17.78-cm electric mill at 204 DEG C to flux plus three
minutes. The stocks were pressed at 204 DEG C and 103 MPa for three
minutes (Carver Press, 12.7-cm X 12.7-cm X 3.175-mm mold)and at room
temperature and 103 MPa for three minutes. Two graft copolymers were
used in this example. The first (Graft Copolymer A) was a polypropylene
- acrylic graft copolymer prepared from mfr=4 polypropylene homopolymer
(100 parts) and a 93:2:5 mixture of methyl methacrylate:ethyl
acrylate:methacrylic acid (100 parts). Polymerization was done in
Isopar E solvent at 160 DEG C at 50% solids over one hour with a
di-t-butyl peroxide radical flux of 0.00012. The product isolated
contained 44% acrylate.
The second graft copolymer (Graft Copolymer B) was a polypropylene -
acrylic graft copolymer prepared from mfr=4 propylene homopolymer (100
parts) and a 95:5 mixture of methyl methacrylate:ethyl acrylate (150
parts). Polymerization was done in Isopar E solvent at 155 DEG C at 60%
solids. The feed time was 60 minutes and the radical flux was 0.00010.
The product contained 53% acrylate.
Addition of the graft copolymer results in an increase in tensile
strength and modulus.
Columns=6 Compatibilization of EVOH and Polypropylene Head Col 1: EVAL
(grams) Head Col 2: PP (grams) Head Col 3: graft copolymer (grams) Head
Col 4: notched Izod tensile (J/m) Head Col 5: tensile strength (MPa)
Head Col 6: tensile modulus (MPa) 903002129.852570 90255 <1>
2148.063190 90255 <2> 2246.753270 309001821.371930 307515 <1>
1829.792140 307515 <2> 1330.412030 1 - Graft Copolymer A (see text
above). 2 - Graft Copolymer B (see text above).