Masterbatch formulations for polyolefin applications

Masterbatches comprising high density polyethylene (HDPE) are used for the production of polyolefin articles, particularly films. Employing HDPE in a masterbatch alone or in combination with a hydrocarbon resin and/or a polyolefin ultimately results in extruded polyolefin articles of optimal stiffness and ductility. Employing a high density polyethylene in combination with a hydrocarbon resin and a polyolefin in a masterbatch causes the masterbatch to solidify more rapidly and be pelletized more efficiently.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to masterbatches and their method of use for 
producing polyolefin articles, particularly films. High density 
polyethylene can be incorporated into the masterbatch alone or in 
combination with a hydrocarbon resin and/or a polyolefin in and when used 
in combination with a hydrocarbon resin causes the masterbatch to solidify 
more rapidly and be pelletized more efficiently (improved compounding 
efficiency). These masterbatches ultimately result in extruded polyolefin 
in articles, such as cast polypropylene films, of optimal stiffness and 
ductility. 
2. Discussion of Background 
Polyolefins are plastic materials useful for making a wide variety of 
valued products due to their combination of stiffness, ductility, barrier 
properties, temperature resistance, optical properties, availability, and 
low cost. Being a semi-crystalline polymer, a number of these important 
properties such as stiffness, barrier properties, temperature resistance, 
and optical properties, depend on the ability of the polyolefin to 
crystallize in the most effective manner, and to the desired degree. 
The process for forming a polyolefin product strongly affects the 
crystallization behavior of the material and its ultimate properties. For 
instance, when polypropylene is cast into thin film, the polymer cools so 
quickly that the ultimate level of crystallinity is reduced by this 
"quenching" process, and correspondingly the stiffness of the film is 
reduced. Cast polypropylene films typically exhibit a stiffness, measured 
as tensile modulus, of nominally 100 Kpsi. Highly oriented polypropylene 
(OPP) films typically exhibit modulus values 2-4 times higher than the 
values for cast polypropylene film while non-oriented thick molded 
articles typically exhibit modulus values nominally 50% to 100% higher 
then cast polypropylene film. Also when making cast film, it is important 
that the polypropylene melt solidify quickly to promote high production 
rates, and also that the crystalline regions which are formed are not so 
large in size that they confer haze to the film. 
Other molded polyolefin articles, particularly thin gauge products made by 
thermoforming, injection molding, or blow molding, are subject to similar 
constraints. Faster crystallization which permits rapid demolding and 
stiffer products is desired, as well as good optical properties promoted 
by small crystalline domain size. 
As a means for improving the stiffness of polyolefins, the addition of a 
high softening point hydrocarbon resin to polyolefins, such as 
polypropylene, is known. The composition of the hydrocarbon resin must be 
such that it exhibits a significantly higher glass transition temperature 
(Tg) than the amorphous regions of the polypropylene (Tg around 
-10.degree. C.), and the hydrocarbon resin must be highly compatible in 
the polypropylene. It is believed that the effect of the hydrocarbon resin 
is to increase the Tg of the amorphous polypropylene fraction and by doing 
so increase its tensile modulus at temperatures below 38.degree. C. 
The hydrocarbon resins described above are friable solids which exhibit 
very low melt viscosity at the temperatures normally used to process 
polyolefin. An effective way to blend hydrocarbon resin into polyolefin is 
in a separate compounding step prior to the final use of the blend. It is 
difficult to incorporate hydrocarbon resin into polypropylene during an 
actual conversion step (for example film casting, sheet extrusion, etc.) 
because of the hydrocarbon resins dusting characteristics and low melt 
viscosity. A more effective way to incorporate hydrocarbon resin into 
polyolefin during the conversion step is to add the resin in concentrate 
form as a mixture of resin with polyolefin. U.S. Pat. No. 5,213,744 
describes a process of forming a concentrate consisting of a simple binary 
mixture of hydrocarbon resin and polyolefin, and using this concentrate as 
a more effective way of incorporating hydrocarbon resin into a polyolefin 
film formulation at a level of 5 wt. % to 30 wt. %. 
Although the stiffening caused by adding hydrocarbon resin is desirable, it 
can be achieved only by adding high levels of hydrocarbon resin (typically 
at or above 5 wt. %) to the total polyolefin formulation, and only if the 
softening point of the hydrocarbon resin is 100.degree. C. or higher, the 
stiffening effect increases as the hydrocarbon resin content and softening 
point increase. While the stiffening effect caused by the addition of 
hydrocarbon resin to polyolefins, is desirable, adding high levels of 
resin (e.g., above 5 wt. %), has a negative impact on ductility and 
results in increased formulation cost. Therefore, it would be highly 
desirable to enhance polyolefin stiffness by addition of hydrocarbon resin 
to the polypropylene at levels below 5 wt. % and preferably below 3 wt. %. 
SUMMARY OF THE INVENTION 
Before further discussion, a definition of the following terms will aid in 
the understanding of the present invention. 
Masterbatch--a mixture of 2 or more ingredients which simplifies adding 
these ingredients to a material as a blend, rather than as a plurality of 
individual ingredients. In the present case masterbatch is defined as a 
blend of one or more ingredients (additives) in the proper proportion by 
weight with a polymer or mixture of polymers, where the total formulation 
is ultimately added to a second polymer, which is either the same or 
different than the polymer or mixture of polymers which comprise the 
masterbatch, as the means of incorporating the additives into the second 
polymer. 
Additive--An additive is typically a substance added to a polymer which is 
non-polymeric in nature, or if it is polymeric in nature is substantially 
different in type and character from the polymer to which it is added. In 
the present case, additive refers to both the hydrocarbon resin and high 
density polyethylene (HDPE) which are ultimately blended with polyolefin. 
By our definition, HDPE is considered an additive although it could also 
be considered a polymer in the context of the masterbatch definition. 
Polyolefin Blend--the final formulation resulting from the combination of a 
masterbatch with a polyolefin polymer or mixture of polymers. Accordingly, 
the polyolefin polymer or polymers into which the masterbatch is included 
is termed the blend polyolefin. 
Hydrocarbon Resin--refers to low molecular weight resin products of about 
10,000 number average molecular weight (Mn) or less derived from 
polymerizing feedstocks from the coal or petrochemical industries, resin 
products derived from terpene, rosin, or other feedstocks. This term will 
not be used to refer to high molecular weight polymer products of about 
50,000 number average molecular weight or more. 
As discussed above, adding a high softening point hydrocarbon resin to a 
polyolefin, such as polypropylene, will increase the glass transition 
temperature (Tg) of the amorphous phase of the polyolefin and modify its 
properties. One effect of hydrocarbon resin addition is greater stiffness. 
However to achieve significant property modification the hydrocarbon resin 
must be added at levels at or above 5 wt. % of the total polyolefin blend. 
Adding high levels of hydrocarbon resin has a negative impact on ductility 
and impact properties, increases formulation cost, and slows down the 
crystallization rate of the polyolefin. It would therefore be desirable to 
achieve the favorable effects of hydrocarbon resin addition at lower 
hydrocarbon resin add levels. 
The present inventor has discovered that adding low levels of high density 
polyethylene (HDPE) to a polyolefin, such as polypropylene, accelerates 
the crystallization rate of the polyolefin when the high density 
polyethylene (HDPE) is adequately dispersed into the polyolefin and the 
ingredients are effectively added. It appears that under fast cooling 
conditions the HDPE crystallizes faster than the polyolefin and as the 
HDPE begins to crystallize it acts as a nucleator for subsequent 
crystallization of the polyolefin. 
Accordingly, the present invention is directed to masterbatches for 
modifying polyolefins in which the masterbatch is a combination of a 
hydrocarbon resin and a high density polyethylene (HDPE) mixed with a 
polyolefin polymer, or a binary mixture of HDPE with a polyolefin, or a 
binary mixture of a high density polyethylene and a hydrocarbon resin. The 
masterbatch components should be intimately combined utilizing 
conventional techniques such as; dry blending, extrusion mixing and melt 
blending and pelletizing. In a preferred embodiment, the masterbatch is 
provided in pellet form by melt blending and pelletizing the masterbatch 
components. 
Adding HDPE and hydrocarbon resin to a polyolefin polymer as a masterbatch 
prior to extrusion of the article results in favorable characteristics in 
the final article. 
Additionally, the present inventor has discovered that adding low levels of 
HDPE to a polyolefin, as a masterbatch, without the hydrocarbon resin, 
gives desirable property modifications to the finished product. 
In each case, the ingredients and proportion by weight of the ingredients 
in the masterbatch are such that they become intimately mixed into a 
formulation during the final processing step to make a final article. 
In an embodiment of the present invention the masterbatch for modifying 
polyolefin polymers comprises about 10-90 wt % high density polyethylene 
and a hydrocarbon resin alone or in combination with a polyolefin. The 
polyolefin may be present in a concentration of up to about 85 wt. % of 
the total masterbatch and can be any a olefin polymer comprised of 
monomers containing from about 2 to 8 carbon atoms with propylene polymers 
being most preferred. The polyolefin may be an ethylene polymer with a 
density up to about 0.930 g/cm.sup.3. 
In a preferred embodiment, the polyolefin is selected from the group 
consisting of polypropylene and polymers of polypropylene with up to about 
20 wt. % of monomers selected from the group consisting of ethylene and 
C.sub.4 to C.sub.8 mono .alpha. olefin. 
The polyolefin in the masterbatch is selected to be similar to the blend 
polymer, or if significantly different from the blend polymer, to be 
present in low levels in the masterbatch so that it is incorporated at low 
levels (less than 5 wt. %) in the final blend. 
The hydrocarbon resin and high density polyethylene may be present at a 
combined concentration of about 15 wt. % to 100 wt. % of the total 
masterbatch, and the hydrocarbon resin and high density polyethylene may 
be in a relative proportion by weight of between about 0:1 to 10:1 in the 
masterbatch, provided the concentration of high density polyethylene never 
exceeds about 40 wt. % of the total masterbatch unless the weight ratio of 
hydrocarbon resin to high density polyethylene in the masterbatch is at 
least about 0.5:1 or greater. 
In a preferred embodiment of the masterbatch, the high density polyethylene 
has a density greater than about 0.935 g/cm.sup.3 and a melt index greater 
than about 1.0 g/10 min, while the hydrocarbon resin is an aliphatic 
compatible resin of number average molecular weight of 10,000 or less with 
an odorless mineral spirit (OMS) cloud point of less than about 0.degree. 
C. and a ring and ball softening point of 100.degree. C. or above 
(obtained through use of ASTM 28-67). In another masterbatch embodiment, 
the hydrocarbon resin is an aliphatic compatible resin having an OMS cloud 
point of less than about -40.degree. C. 
Odorless mineral spirit (OMS) cloud point was determined through the 
following test. Ten (10 wt. %) weight percent of a resin is placed in a 
test tube containing ninety (90 wt. %) weight percent of an odorless 
mineral spirit (OMS) which is Shell-Sol 71 (available from Shell Chemical 
Company, Houston, Tex.). The test tube containing the sample is heated 
until a clear solution is formed. The solution is then cooled until 
turbidity of the solution is observed. The onset of turbidity is recorded 
as the initial cloud point. Cooling of the solution is continued until the 
solution is completely turbid. The final cloud point is the point at which 
total turbidity is observed. 
In additional embodiments of the masterbatch, the high density polyethylene 
can have a density greater than about 0.950 g/cm.sup.3 or a density 
greater than about 0.960 g/cm.sup.3 and a melt index greater than about 
5.0 g/10 min or greater than about 10.0 g/10 min, respectively. In a 
preferred masterbatch embodiment, the high density polyethylene has a 
density of about 0.950 g/cm.sup.3 or greater and a melt index between 
about 10-30 g/10 min. 
In a preferred embodiment, the masterbatch may comprise a hydrocarbon resin 
and a high density polyethylene in a proportion by weight of hydrocarbon 
resin to high density polyethylene of about 0.5:1 to 4:1. 
In a most preferred embodiment, the masterbatch composition comprises a 
polypropylene, for example polypropylene homopolymer, as the polyolefin. 
In another preferred embodiment, the masterbatch for modifying polyolefin 
polymers comprises about 5 to 50 wt % high density polyethylene, about 30 
to 60 wt % hydrocarbon resin and about 10 to 45 wt % polypropylene. In 
another preferred embodiment, the masterbatch for modifying polyolefin 
polymers comprises about 5 to 25 wt % high density polyethylene, about 40 
to 60 wt % hydrocarbon resin and about 25 to 45 wt % polypropylene. For 
example, a masterbatch for modifying polyolefin polymers may comprise 
about 15 wt % high density polyethylene, about 50 wt % hydrocarbon resin 
and about 35 wt % polypropylene. In a most preferred embodiment, the 
masterbatch for modifying polyolefin polymers comprises about 40 wt % high 
density polyethylene, about 40 wt % hydrocarbon resin and about 20 wt % 
polypropylene. 
In yet another embodiment, the masterbatch for modifying polyolefin 
polymers comprises about 15 to 50 wt % high density polyethylene and about 
50 to 85 wt % polypropylene. Preferred embodiments include about 40 or 50 
wt % high density polyethylene and about 50 or 60 wt % polypropylene. In a 
most preferred embodiment, the masterbatch for modifying polyolefin 
polymers comprises about 30 wt % high density polyethylene and about 70 wt 
% polypropylene. 
The present invention is also directed to modified polyolefin blend 
compositions which result from blending the ingredients of the masterbatch 
described above into a polyolefin polymer using conventional equipment 
such as a twin-screw extruder. 
Accordingly, in another embodiment of the present invention, a modified 
polyolefin composition is comprised of a polyolefin, about 0.3 wt. % to 
about 4.0 wt. % of a high density polyethylene and up to about 5 wt. % of 
a hydrocarbon resin. In the modified polyolefin composition, various 
polyolefins can be utilized, for example a polymer comprised of a 
mono-alpha olefin containing from about 2 to 8 carbon atoms, with 
propylene polymers being preferred. The polyolefin may be an ethylene 
polymer with a density less than about 0.930 g/cm.sup.3. In a preferred 
embodiment, the polyolefin is selected from the group consisting of 
polypropylene and polymers of polypropylene with up to about 20 wt. % of 
monomers selected from the group consisting of ethylene and C.sub.4 to 
C.sub.8 mono .alpha. olefin. 
In a preferred embodiment of the modified polyolefin blend, the high 
density polyethylene has a density greater than about 0.935 g/cm3 with a 
melt index greater than about 1.0 g/10 min. In additional embodiments of 
the blend, the high density polyethylene can have a density greater than 
about 0.950 g/cm.sup.3 or a density greater than about 0.960 g/cm.sup.3 
and a melt index greater than about 5.0 g/10 min or greater than about 
10.0 g/10 min, respectively. In a preferred modified polyolefin blend, the 
high density polyethylene has a density of about 0.950 g/cm.sup.3 or 
greater and a melt index between about 10-30 g/10 min. 
In another preferred embodiment of the modified polyolefin blend 
composition, the modified polyolefin composition comprises about 1.5 wt. % 
to about 2.5 wt. % of a high density polyethylene and about 2 wt. % to 3.5 
wt. % of a hydrocarbon resin, wherein the polyolefin comprises 
polypropylene. 
In the modified polyolefin composition, it is preferred that the 
hydrocarbon resin is an aliphatic compatible resin with Mn of 10,000 or 
less having an odorless mineral spirit (OMS) cloud point of less than 
0.degree. C. and a ring and ball softening point of 100.degree. C. or 
above. Additionally, the modified polyolefin composition may comprise an 
aliphatic compatible hydrocarbon having an odorless mineral spirit (OMS) 
cloud point of less than -40.degree. C. 
In a most preferred embodiment, the modified polyolefin composition 
comprises a polypropylene homopolymer as the polyolefin modified by a 
masterbatch comprising a hydrocarbon resin and a HDPE. It is further 
preferred that the polyolefin composition be modified by combining about 
6% of a masterbatch comprised of hydrocarbon resin and HDPE with the blend 
polyolefin. The modification of the polyolefin by the addition of low 
levels of hydrocarbon resin and HDPE achieves several enhanced properties. 
First, the addition of low levels of hydrocarbon resin and HDPE increases 
the tensile modulus value of the polyolefin by 15% to 70% above the value 
of the polyolefin polymer itself. More typically, increases of 20% to 50% 
are achieved by this modification. A principle, but not exclusive, use for 
formulations of this type is in cast film where higher stiffness is a 
desirable quality. 
Secondly, modified polypropylene blends altered in this manner realize 
improved crystallization behavior where the blend will solidify 
(crystallize) from the melt faster and/or in a different manner than the 
unmodified polypropylene. This effect is important in many fabrication 
processes such as film production, blow molding, injection molding, and 
sheet thermoforming where productivity and optical quality depend on the 
speed and nature of the crystallization process. Accordingly, the modified 
blends are useful for forming various articles such as film, fibers, 
bottles, molded articles and sheets. 
Finally, with regard to the modified polypropylene blend, the addition of 
the hydrocarbon resin and HDPE modifiers does not deteriorate the optical 
properties of the blend, and in many instances improves optical quality. 
Thin (1-4 mils thick) cast films made from these modified polypropylene 
formulations demonstrate excellent clarity, low haze values (less than 5% 
as measured by ASTM D-1003), and also high 45.degree. gloss values of 70% 
to 90% (measured by ASTM D-2457). This last effect was especially 
unexpected. Intuitively it is expected that adding HDPE to polypropylene 
will increase haze substantially and lead to surface roughness and poor 
gloss. However, good optical properties are retained or improved by the 
incorporation of low levels of an effective grade of a high density 
polyethylene if it is intimately dispersed in the final polypropylene 
blend in accordance with the present invention. 
Additional aspects of the present invention are directed to the process and 
resulting polyolefin articles formed from polymer blend compositions 
resulting from mixing a masterbatch as described above into a polyolefin 
and the subsequent blending and extrusion of the modified polyolefin to 
form a polyolefin article. 
Accordingly, the present invention is directed to a process for producing a 
polyolefin article comprising providing a masterbatch may comprise about 
10-90 wt % high density polyethylene and at least one member selected from 
the group consisting of polyolefin and hydrocarbon resin. The polyolefin 
may be present at a concentration of up to about 85 wt. % of the total 
masterbatch and various polyolefins can be utilized, for example a polymer 
comprising mono-alpha olefin monomers containing from about 2 to 8 carbon 
atoms with propylene polymers being preferred. The polyolefin may be an 
ethylene polymer with a density up to about 0.930 g/cm.sup.3. In a 
preferred embodiment, the polyolefin is selected from the group consisting 
of polypropylene and polymers of polypropylene with up to about 20 wt. % 
of monomers selected from the group consisting of ethylene and C.sub.4 to 
C.sub.8 mono .alpha. olefin. 
The hydrocarbon resin and high density polyethylene may be present in at a 
concentration of about 15 wt. % to 100 wt. % of the total masterbatch, and 
the hydrocarbon resin and high density polyethylene may be present in a 
proportion by weight of about 0:1 to 10:1 in the masterbatch, provided the 
concentration of high density polyethylene never exceeds about 40 wt. % of 
the total masterbatch mixture unless the weight ratio of hydrocarbon resin 
to high density polyethylene in the masterbatch is at least about 0.5:1 or 
greater. The masterbatch is preferably melt blended and pelletized. The 
masterbatch is subsequently mixed with polyolefin to form a polyolefin 
blend which is then extruded to form a polyolefin article. 
In an embodiment of the present invention, the polyolefin blend extruded to 
form the polyolefin article comprises about 2 wt. % to 25 wt. % of the 
masterbatch, with about 4 wt. % to 10 wt. % of the masterbatch being 
preferred, and additionally is comprises about 0.3 wt % to 4.0 wt. % high 
density polyethylene and up to about 5 wt. % hydrocarbon resin. It is also 
preferred that the polyolefin blend comprises about 6% of the masterbatch. 
In another preferred embodiment of the present method, the high density 
polyethylene has a density greater than 0.935 g/cm.sup.3 and a melt index 
greater than 1.0 g/10 min. and the hydrocarbon resin is an aliphatic 
compatible resin with a number average molecular weight 10,000 or less 
with an odorless mineral spirit (OMS) cloud point of less than 0.degree. 
C. and a ring and ball softening point of 100.degree. C. or above. 
In a further embodiment of the present process, the masterbatch comprises a 
hydrocarbon resin and a high density polyethylene in a proportion by 
weight of hydrocarbon resin to high density polyethylene of about 0.5:1 to 
4:1. 
In still another preferred embodiment of the present method, the 
masterbatch comprises about 4 wt. % to 10 wt. % of the polyolefin blend, 
with about 6 wt. % being most preferred. 
In a further preferred method embodiment, the polyolefin blend comprises 
about 1.5 wt. % to 2.5 wt. % high density polyethylene and about 2 wt. % 
to 3.5 wt. % hydrocarbon resin. 
In a most preferred process embodiment, the polyolefin polymer comprises 
polypropylene, such as a polypropylene homopolymer, in the masterbatch and 
the final polyolefin blend. 
In a preferred embodiment of the process, the masterbatch comprises about 5 
to 50 wt % high density polyethylene, about 30 to 60 wt % hydrocarbon 
resin and about 10 to 45 wt % polypropylene and the polyolefin in the 
polyolefin blend comprises polypropylene. In another preferred embodiment, 
the masterbatch comprises about 15 wt % high density polyethylene, about 
50 wt % hydrocarbon resin and about 35 wt % polypropylene and the 
polyolefin in the polyolefin blend comprises polypropylene. In a most 
preferred embodiment, the masterbatch comprises about 40 wt % high density 
polyethylene, about 40 wt % hydrocarbon resin and about 20 wt % 
polypropylene and the polyolefin in the polyolefin blend comprises 
polypropylene. 
In a further preferred embodiment of the process, the masterbatch comprises 
about 15 to 50 wt % high density polyethylene and about 50 to 85 wt % 
polypropylene and the polyolefin in the polyolefin blend comprises 
polypropylene. In a preferred embodiment the masterbatch comprises about 
40 or 50 wt % high density polyethylene and about 50 or 60 wt % 
polypropylene. In a most preferred embodiment, the masterbatch comprises 
about 30 wt % high density polyethylene and about 70 wt % polypropylene 
and the polyolefin in the polyolefin blend comprises polypropylene. 
In another embodiment of the present invention, polyolefin articles are 
produced according to the above method. Polypropylene articles which are 
cooled very quickly, such as cast film, benefit from an additive which 
enhances stiffness by increasing the crystallization level in the film. 
Likewise other thin molded articles, where optical properties and 
stiffness are important attributes, benefit from an additive which 
favorably affects the crystallization process and also enhances product 
stiffness. Accordingly, polyolefin articles which benefit from the 
composition and methods of the present invention include, blow molded 
polypropylene products, thermoformable polypropylene sheet products and 
polypropylene fiber products. 
In another embodiment the extruded polyolefin article is a film which 
comprises a high density polyethylene and at least one member selected 
from the group consisting of polyolefin and hydrocarbon resin. For 
example, the film may comprise high density polyethylene, polyolefin and 
hydrocarbon resin or a high density polyethylene and polypropylene. 
The polyolefin in the film may comprise a polymer comprising mono-alpha 
olefin monomers containing about 2 to 8 carbon atoms. In a preferred 
embodiment, the polyolefin comprises polypropylene. 
DETAILED DESCRIPTION OF THE INVENTION 
In the first aspect of the present invention, there are provided 
masterbatches comprising a polyolefin and a high density polyethylene; a 
hydrocarbon resin and a high density polyethylene and a combination of a 
polyolefin, a high density polyethylene and a hydrocarbon resin, in which 
the components of the masterbatch are present in amounts effective to 
increase the stiffness of the final polyolefin containing article. 
Preferably, the masterbatch formulation is used in polypropylene 
applications, such as in cast polypropylene films, but is not exclusively 
limited to this area. The masterbatch must be mixable with the polyolefin 
prior to the processing step and be uniformly mixed into the final product 
(e.g. cast film) by being homogenized into the product during the 
processing (typically extrusion) step. 
Hydrocarbon resins suitable for use as additives in the masterbatch are 
aliphatic compatible products derived from rosin, terpene, or hydrocarbon 
feedstocks having a ring and ball (R&B) softening point of 70.degree. C. 
or above. These hydrocarbon resins have a number average molecular weight 
(Mn) as measured by vapor phase osmometry below the molecular weight of 
the polyolefin. Suitable hydrocarbon resins have a number average 
molecular weight less than 10,000, with hydrocarbon resins of Mn less than 
5,000 being preferred, for example hydrocarbon resins of at least about 
500 to 2000 Mn. Hydrocarbon resins include aliphatic compatible resins 
with an odorless mineral spirit (OMS) cloud point of less than 0.degree. 
C., but preferably less than -40.degree. C., and with a R&B softening 
point of 100.degree. C. or above, with fully hydrogenated terpene or 
hydrocarbon resins having a softening point of about 120.degree. C. or 
higher being preferred and those with a R&B softening point of between 
about 135.degree. C. and 160.degree. C. being most preferred. Examples of 
preferred hydrocarbon resins include REGALITE.RTM. R-125 Resin, 
REGALREZ.RTM. 1139 Resin which is a hydrogenated pure aromatic hydrocarbon 
resin, and REGALREZ.RTM. 1128 Resin, which are hydrogenated resins with a 
R&B softening point of above 120.degree. C., all of which are available 
from Hercules Incorporated. 
The most preferred hydrocarbon resin for use in this application are fully 
hydrogenated hydrocarbon resins with a R&B softening point greater than 
135.degree. C. For example, REGALREZ.RTM. 1139 hydrocarbon resin 
(available from Hercules Incorporated) is a low molecular weight 
hydrogenated hydrocarbon resin which exhibits a high Tg (around 90.degree. 
C.) and is highly compatible with aliphatic polymers. Other similar 
hydrocarbon resins exhibiting low molecular weight, aliphatic 
compatibility, and high softening point can also be used with similar 
effectiveness such as those hydrocarbon resins described in U.S. Pat. No. 
5,213,744, the disclosure of which is hereby incorporated by reference in 
its entirety. 
When utilized in a masterbatch, the hydrocarbon resin is believed to act as 
a "diluent" which compatibilizes the mixture of the two dissimilar 
polymers. The hydrocarbon resin also acts to reduce the melt viscosity of 
a polymer masterbatch, which improves the ability to thoroughly disperse 
the ingredients of the masterbatch into the final blend. When added to 
polypropylene, the hydrocarbon resin associates with the amorphous phase 
of the polyolefin and raises the Tg of the polyolefin amorphous phase and 
ultimately its modulus. 
High density polyethylene polymers suitable as additives for the 
masterbatch are those having a density greater than about 0.935 
g/cm.sup.3. Preferably the density should be greater than about 0.950 
g/cm.sup.3, with the most preferred HDPE having a density of about 0.960 
g/cm.sup.3 or greater. The % crystallinity of the HDPE increases with 
increasing density, and thus density is a coarse measure of the ability of 
the HDPE to initiate crystallization. 
The effectiveness of HDPE is dependent on achieving a thorough and finely 
dispersed distribution of HDPE throughout the final polyolefin blend. As a 
result, the effectiveness of the HDPE is dependent on the degree of 
dispersion of the HDPE in the masterbatch, combined with the effectiveness 
of the masterbatch in dispersing the HDPE throughout the polyolefin blend. 
In order to be effectively dispersed in the masterbatch formulation, the 
molecular weight (MW) of the HDPE should be suitably low. Melt index (MI) 
(ASTM D-1238, 190.degree. C. and 2.16 Kg. load) is a good indicator of 
relative molecular weight and flow. HDPE grades effective in this 
application should have a MI greater than about 1.0 g/10 min., and 
preferably above about 5.0 g/10 min. Most preferred are grades of HDPE 
with a MI greater than about 10 g/10 min. For example, an effective grade 
of HDPE is a grade having a MI value between about 10-30 g/10 min. 
(190.degree. C., 2.16 Kg.) and a density of 0.950 g/cm.sup.3 or greater. 
HDPE having a lower MW and higher flow is desirable because both factors 
make it easier to disperse HDPE throughout the polyolefin in finer and 
more numerous domains. However if the MI is too high, the melt fluidity 
can be excessive and hinder effective dispersion of the HDPE into the 
polyolefin. HDPE with the highest density displays the fastest and most 
complete crystallization behavior. HDPE which exhibits a strong affinity 
to crystallize is desirable. A highly effective HDPE for use in this 
invention is ALATHON H6611 polymer (from Lyondell Petrochemical Company) 
which has an MI of 11.0 g/10 min. and a density of 0.965 g/cm.sup.3. 
Although not being restricted to a particular mechanism, it is believed 
that the function of the HDPE in the masterbatch formulation is to modify 
the crystallization behavior of the polyolefin, preferably 
homo-polypropylene. The HDPE does not function as a bulk alloying 
ingredient, which is its function in conventional applications but rather 
behaves like a nucleator; an agent which can accelerate the 
crystallization rate or change the crystallization behavior of a material, 
even when used at very low levels. 
Desirable masterbatch compositions contain additive concentrations which 
incorporate sufficient quantities of high density polyethylene polymer in 
conjunction with a hydrocarbon resin and/or a polyolefin to achieve 
desired blend compositions with enhanced properties. In the masterbatch 
formulation both the high softening point hydrocarbon resin and the HDPE 
are considered active ingredients or additives. The concentration of 
active ingredients in the masterbatch can range from 5 wt. % to 100 wt. %. 
The preferred range of active ingredients is from 50 wt. % to 100 wt. 
Accordingly in one embodiment, the additives are present in the 
masterbatch at a level of about 15 wt. % to 80 wt. % while the polyolefin 
is about 20 wt. % to 85 wt. %. In a preferred embodiment, the additives 
are present at about 15 wt. % to 100 wt % while polyolefin levels of the 
masterbatch are about 0 wt. % to 85 wt. %. In another embodiment, 
additives in the masterbatch are present at about 80 wt. %, while the 
masterbatch levels of the polyolefin is about 20 wt. %. 
The acceptable proportion by weight of hydrocarbon resin and HDPE which 
will give the required property modification, range from a hydrocarbon 
resin/HDPE weight ratio of 0/1 (no resin added, 100% HDPE as the active 
agent) to a weight ratio of 10/1. The preferred range of compositions is 
between a hydrocarbon resin/HDPE weight ratio of about 0.5/1 to 4/1. In 
the masterbatch formulation the concentration of HDPE should never exceed 
40 wt. % of the total mixture unless the weight ratio of hydrocarbon 
resin/HDPE is 0.5/1 or greater. 
In the masterbatch formulation, various polyolefins can be utilized, for 
example a polymer comprised of mono-alpha olefin monomers containing about 
2 to 8 carbon atoms, with propylene polymers being preferred. The 
polyolefin may be an ethylene polymer with a density less than about 0.930 
g/cm.sup.3. In a preferred embodiment, the polyolefin is selected from the 
group consisting of polypropylene and polymers of polypropylene with up to 
about 20 wt. % of monomers selected from the group consisting of ethylene 
and C.sub.4 to C.sub.8 mono .alpha. olefin. Accordingly, the polyolefin 
polymer may comprise a homopolymer of a C.sub.2 to C.sub.8 olefin or a 
copolymer of two or more C.sub.3 to C.sub.8 olefins, including but not 
limited to, propylene, butene-1, hexene and 4-methyl pentene-1. The 
present invention can also employ a random copolymer of ethylene and 
propylene such as an isotactic propylene-ethylene copolymer with a density 
of from 0.86 to 0.92 g/cm.sup.3 as measured at 23.degree. C. according to 
ASTM D1505 and a melt flow index of from 2 to 15 g/10 min as determined 
according to ASTM D1238 (conditions at 230.degree. C. and 2.16 kg.). The 
propylene copolymers may be synthesized by employing conventional 
polymerization methods employing catalysts such as AlCl.sub.3 and 
TiCl.sub.4. Polyolefins that fit within the above definition are described 
in U.S. Pat. No. 5,213,744, which is hereby incorporated by reference in 
its entirety. The polyolefin portion of the masterbatch is selected to be 
similar to the polymer to which the melt blend will be added, or if 
significantly different, to be present at amounts in the masterbatch so 
that it is present at levels below 5 wt. % in the polymer article. 
With respect to masterbatch formulations used for film applications, 
various grades of polypropylene polymer are preferred, for example a high 
molecular weight stereoregular semi-crystalline polypropylene. If stiffer 
cast polypropylene film is desired, the use of polypropylene homopolymer 
is most preferred. Polypropylene melt flow rates (230.degree. C., 2.16 Kg. 
load) of from about 0.5-50 g/10 min. can be utilized in the present 
invention, with between 2-10 g/10 min. being preferred and a MFR of 
between about 2.0-5.0 g/10 min being the most preferred. 
The melt flow rate (MFR) of the masterbatch and the MFR of the polyolefin 
blend polymer help to determine the efficiency with which the masterbatch 
is distributed into the polyolefin. If the polyolefin blend polymer 
exhibits a low MFR, the masterbatch will be best distributed if it also 
exhibits a MFR typically between about 2.times. and 20.times. the value of 
the polyolefin polymer. If the blend polymer has a higher MFR, then a 
masterbatch formulation with a MFR higher than the previous case is 
desirable, again nominally 2.times. to 20.times. the MFR of the polyolefin 
polymer into which the masterbatch will be combined. 
The masterbatch formulations of this invention can be used to produce 
ranges of polyolefin blend compositions containing high density 
polyethylenes alone or in combination with a hydrocarbon resin which 
exhibit enhanced mechanical and optical properties. These polyolefin 
compositions can be particularly useful in cast film applications. 
The polyolefin blend should incorporate the necessary additives at 
masterbatch add levels between about 2 wt. % to 25 wt. %, with about 4 wt. 
% to 10 wt. % being preferred and between about 4 wt. % to 8 wt. % being 
most preferred. 
The polyolefin blend polymer in the final polymer formulation comprises any 
grade of polymer or blend of polymers as described above for the 
masterbatch, which can be altered to the described degree by the modifiers 
(e.g., hydrocarbon resin and HDPE) present in the masterbatches. For 
example, the polyolefins employed in the final blend used to make the 
extruded product, for example a film, may be selected from one of the 
above mentioned polyolefins recited as being suitable in the masterbatch. 
Although the polyolefin used in the masterbatch and the polyclefin used in 
the blend may indeed differ, it is preferred that they be similar. In a 
most preferred embodiment, the present invention is directed to a final 
polymer formulation comprising polypropylene polymer modified by the 
addition of masterbatches containing low levels of HDPE alone or in 
conjunction with a hydrocarbon resin. The resulting polyolefin blend 
exhibits improved properties compared to the properties of the polyolefin 
polymer alone. In a most preferred embodiment, the formulations are 
comprised of a polypropylene modified by melt blending with low levels of 
hydrocarbon resin and HDPE. The final blend exhibits any or all of the 
following properties, A) Modulus values which are 15% to 70% greater than 
the value of the unmodified polypropylene polymer, B) Superior 
crystallization behavior, and C) Haze values comparable to or better than 
the unmodified polypropylene. 
Polypropylene homopolymer is most effectively modified by the additives 
described above and is preferred in cast film application of this 
invention. In cast films, polypropylene homopolymer having a MFR of 2-10 
g/10 min. (230.degree. C., 2.16 Kg.) is preferred. A typical MFR for 
polypropylene homopolymer used in cast film applications, for which this 
invention is particularly directed, is nominally 7 g/10 min. 
At hydrocarbon resin add levels of 5 wt. % or more, the hydrocarbon resin 
would have adverse effects on ductility and impact properties. Because of 
this latter constraint, it is preferred that the hydrocarbon resin be 
incorporated into the final polyolefin (e.g. polypropylene) formulation at 
hydrocarbon levels of from about 0 wt. % to about 5 wt. %, but preferably 
at levels of about 2 wt. % to about 3.5 wt. % of the final propylene 
blend. 
While it is known that high softening point hydrocarbon resins added to 
polyolefins, preferably polypropylene, can increase the modulus of the 
polyolefin, the present inventor has discovered that combining low levels 
of HDPE with low levels of hydrocarbon resin is an even more effective way 
to stiffen polyolefins such as polypropylene. While investigating this 
issue, it was surprisingly learned that the addition of low levels of HDPE 
alone to polyolefins can also substantially stiffen the polyolefin. It is 
indeed surprising that the above-recited low levels of HDPE added to 
polyolefin realizes a significant improvement in the mechanical properties 
of the polyolefin as demonstrated in the examples below where the addition 
of between 0.7 wt. % to 3 wt. % HDPE (more preferably 1.5 wt. % to 2.5 wt. 
% HDPE) to polypropylene increased the tensile modulus of the material by 
20 to 50%. Low HDPE add levels are therefore preferred because at higher 
HDPE levels the enhancement in polyolefin properties is lost and/or other 
negative attributes caused by the presence of HDPE are observed. 
In the instant invention the HDPE can be incorporated into the modified 
polypropylene formulation at a level ranging from about 0.3 wt. % to about 
4.0 wt. %, with HDPE addition of about 0.7 wt. % to about 3.0 wt. % being 
preferred and an HDPE addition of from about 1.5 wt. % to about 2.5 wt. % 
being most preferred. At lower HDPE levels (e.g. below 0.3 wt. %) it is 
difficult to reproducibly affect the mechanical properties of the 
polypropylene formulation even when good dispersion exists. At higher 
levels (e.g., above 4 wt. %) the domain size of the HDPE increases with 
increasing add levels, causing an increase in haze and a decrease in 
ductility. 
Accordingly, a most preferred embodiment is directed to the incorporation 
into a polypropylene polymer of about 2.0 wt. % to about 3.5 wt. % of high 
softening point hydrocarbon resin along with the required low level of 
HDPE, which is preferably added at about 0.7 wt. % to about 3.0 wt. % 
level. Additionally, the properties of polypropylene polymers can also be 
substantially enhanced by mixing low levels of HDPE into the 
polypropylene, typically at levels between about 0.7 wt. % to 3.0 wt. %, 
exclusive of the use of the hydrocarbon resin.

The present invention will be further illustrated by way of the following 
Examples. 
EXAMPLES 1-3 
In Comparative Examples 1 and 1B, a 50/50 mixture comprising REGALREZ.RTM. 
1139 hydrocarbon resin, manufactured by Hercules Incorporated, and HIMONT 
PD-403 polypropylene homopolymer (obtained from Himont Incorporated) was 
compounded using a BRABENDER D-6 model twin-screw extruder which contain 
two counter rotating intermeshing twin screws which are run at 
approximately 100 RPM. The temperature of the extruder at feed is 
approximately 150.degree. C. and the temperature of the extruder at the 
nozzle is approximately 220.degree. C. The extruder is run under starve 
feeding conditions in order to maximize residence time in the extruder. 
Under these conditions, the sample was mixed in the extruder for 
approximately 2 to 5 minutes in order to completely melt and homogenize 
both components before subsequently being pelletized. 
In Example 2 a mixture of Regalrez.RTM. 1139 hydrocarbon resin (50%) 
combined with PD 403 Polypropylene from Exxon Chemical (35%) and ALATHON 
M6210 HDPE from Lyondell (15%) was dry blended and subsequently melt 
homogenized and pelletized using a twin-screw extruder in the same fashion 
as in Example 1. 
In Example 3 a 70/30 mixture of PD 403 Polypropylene and ALATHON M-6210 
HDPE was likewise compounded as in Examples 1 and 2. In Example 1B, a 
masterbatch was made according to the process of Example 1 except that the 
polypropylene used was ESCORENE 4292 Polypropylene which was a 2.0 MFR 
grade of polypropylene manufactured by Exxon Chemical. 
Each product described in Examples 1-3 was ultimately extruded as a strand 
into a 2 foot long water bath to solidify the melt before pelletization. 
It was noted that the high level of REGALREZ.RTM. 1139 hydrocarbon resin 
in Example 1 slowed down the crystallization/solidification process such 
that the strand was not rigid enough to chop cleanly until 40 seconds time 
elapsed after exiting the chill bath. In Example 2 the presence of the 
HDPE accelerated the solidification process such that the strand was rigid 
and could be cleanly chopped 20 seconds after exiting the cooling bath. In 
Example 3, containing no hydrocarbon resin, the strand was rigid enough to 
pelletize immediately after exiting the cooling bath. 
______________________________________ 
Required 
Required 
Solidifi- 
Strand cation 
Length Time 
RR 1139 Strand (Cooling 
(Pelletizer- 
Ex- Resin HDPE Velocity 
Bath- Cooling 
ample Content Content (ft/sec.) 
Pelletizer) 
Bath) 
______________________________________ 
1,1B 50% -- 15 10 ft. 40 sec. 
(comp.) 
2 " 15% M6210 " 5 ft. 20 sec. 
3 " 30% M6210 " 0 ft. 0 sec. 
______________________________________ 
The slow solidification of Comparative Examples 1 and 1B made it difficult 
to efficiently convert this mixture into pellet form. The faster 
solidification caused by the addition of the ALATHON M-6210 HDPE in 
Example 2 made the process more efficient. 
EXAMPLES 4-7 
In Example 4, a cast film sample was prepared by extruding ESCORENE 4193 
cast film grade polypropylene available from Exxon Chemical Corporation 
having a MFR of 7.5 g./10 min. through a 6" wide film die using a 3/4" 
Brabender single screw extruder. The molten polymer was cast onto a metal 
chill roll cooled with 40.degree. C. water and drawn down to a 1.5 mil 
thickness by adjusting the surface velocity of the casting rolls relative 
to the extrusion rate of the polymer. 
In Example 5 a 94/6 mixture of ESCORENE 4193 PP combined with 6% of the 
REGALREZ.RTM. 1139 concentrate of Example 1 was extruded into 1.5 mil cast 
film under identical conditions used to prepare the films of Example 4. In 
this and subsequent Examples blending of the additives from the 
concentrate into the polypropylene matrix is accomplished during the film 
extrusion step. 
In Example 6, similar films were produced where a compound containing 6% of 
the [REGALREZ 1139+HDPE] concentrate of Example 2 was extruded into film 
under the same conditions as Examples 4 and 5. 
In Example 7, cast films were prepared under conditions identical to the 
previous Examples where a 94/6 mixture of Escorene 4193 with the 
concentrate of Example 3 being used. The tensile properties of each of the 
film samples of Examples 4-7 were measured as listed in the table below. 
______________________________________ 
Yield Tensile 
% Stress Modulus 
Ad- RR- % Haze (Kpsi) (Kpsi) 
ditive 1139 HDPE (%) MD / TD MD / TD 
______________________________________ 
Example 4 
-- -- -- 5.7 3.04 / 3.13 
102 / 114 
(comp.) 
Example 5 
6% .multidot. 1 
3 -- 5.7 3.40 / 3.07 
129 / 121 
(comp.) 
Example 6 
6% .multidot. 2 
3 0.9 8.2 3.63 / 3.49 
135 / 135 
Example 7 
6% .multidot. 3 
-- 1.8 -- HDPE Gels 
HDPE Gels 
______________________________________ 
The films of Example 5 containing REGALREZ 1139 hydrocarbon resin exhibited 
higher stiffness (tensile modulus) and higher MD yield stress than the 
films prepared in Example 4 containing no hydrocarbon resin additive. 
Comparable films of Example 6 containing a low level of ALATHON M-6210 
HDPE in addition to the REGALREZ 1139 exhibited even higher yield stress 
and modulus values than the films of Example 5 containing no HDPE. The 
films made according to Example 7 were very poor in quality because of 
poor dispersion of the HDPE from the Example 3 masterbatch throughout the 
Polypropylene matrix. The films were of poor quality and exhibited poor 
ductility in the transverse direction. 
In Example 6, the presence of low levels of HDPE increased effectiveness of 
REGALREZ 1139 hydrocarbon resin in increasing the stiffness of the cast 
film. By itself, HDPE had no desirable effect because it could not be 
homogeneously dispersed into the polypropylene during the film casting 
step. 
EXAMPLES 8-13 
In Example 8 (comparative), cast films were made from Escorene 4292 
polypropylene available from Exxon Corporation having a nominal MFR of 2.0 
g./10 min. The films were made similar to the procedure in Example 4, 
using a casting roll was cooled with 40.degree. C. water, with the 
exception that the casting roll speed and extrusion rate was adjusted to 
produce films 3 mils thick. 
In Example 9 (comparative), cast film samples were made according to the 
procedure used in Example 8 except that the polymer feed was a 94/6 
mixture of ESCORENE 4292 polypropylene combined with the masterbatch of 
Example 1, such that the final film contained 3% REGALREZ 1139 hydrocarbon 
resin. 
In Example 10, films were made in the same fashion as the previous Examples 
with the exception that the polymer feed was a 94/6 mixture of ESCORENE 
4292 polypropylene and the masterbatch described by Example 2, where the 
final film contained 3% REGALREZ 1139 and 0.9% ALATHON M6210 HDPE. 
The tensile properties of these films were measured in both machine and 
transverse direction as listed in the table below. By comparing the 
values, it can be seen that presence of HDPE in Example 10 increased both 
the tensile modulus and yield strength of the cast films as compared to 
both the unmodified polypropylene film (Example 8) and the film containing 
REGALREZ 1139 but no HDPE (Example 9). 
In Example 11 (comparative), cast polypropylene film was made in the same 
fashion as Example 8 except that the casting roll speed was increased to 
reduce the film thickness to 1.5 mil. 
In Example 12 (comparative), cast film 1.5 mil thick was made similar to 
Example 11 except that the polymer composition was identical to that in 
Example 9, the film containing 3% REGALREZ 1139. 
Likewise in Example 13, similar 1.5 mil film was made using the polymer 
blend used in Example 10 where the final film contained 3% REGALREZ 1139 
and 0.9% ALATHON M6210 HDPE. 
Tensile properties of the films produced are listed in the table below. 
Comparing Examples 8 to 13, the tensile modulus of the thin films was not 
increased to the same degree as the modulus of the thicker films by the 
addition of either REGALREZ 1139 resin or resin combined with ALATHON 
M6210 HDPE. Example 12 compared to Example 13 demonstrates no additional 
effect on tensile modulus from addition of HDPE along with REGALREZ 1139 
resin. 
______________________________________ 
Tensile 
Yield 
Film % Modulus 
Stress 
Ad- Thick- RR- % (Kpsi) (Kpsi) 
ditive ness 1139 HDPE MD / TD 
MD / TD 
______________________________________ 
Example 8 
-- 3.2 mils 
-- -- 112 / 112 
3.02 / 2.88 
(comp.) 
Example 9 
6% .multidot. 1 
3.3 mils 
3 -- 117 / 120 
2.89 / 2.79 
(comp.) 
Example 10 
6% .multidot. 2 
3.0 mils 
3 0.9 141 / 128 
3.39 / 3.11 
Example 11 
-- 1.5 mil -- -- 98 / 99 
2.75 / 2.67 
(comp.) 
Example 12 
6% .multidot. 1 
1.6 mil 3 -- 103 / 107 
2.73 / 2.66 
(comp.) 
Example 13 
6% .multidot. 2 
1.7 mil 3 0.9 108 / 110 
2.67 / 2.64 
______________________________________ 
Comparing Examples 8-13, it is seen that for each polymer composition 
reducing the film thickness decreased the tensile modulus of the ultimate 
film. As the film thickness is reduced, the polymer melt is cooled faster 
and crystallization is forced to occur at lower temperatures. This effect 
impedes the ability of the polymer to crystallize which leads to lower 
modulus values in the thin cast films. 
It was noted that the higher modulus values observed for films containing 
both REGALREZ 1139 hydrocarbon resin and ALATHON M6210 HDPE could only be 
developed under limited conditions of film thickness combined with casting 
roll temperature. Reducing film thickness or lowering the casting roll 
temperature both have the effect of impeding the ability of the polymer to 
crystallize from the melt, and both conditions greatly reduced 
effectiveness of low levels of ALATHON M6210 HDPE for modifying the 
mechanical properties of cast polypropylene film. The synergistic effect 
from adding HDPE along with hydrocarbon resin to cast polypropylene film 
formulations appears related to the effect of the HDPE on the 
crystallization of the polypropylene during the film casting step. This 
effect is not achieved by generic addition of low levels of HDPE into the 
formulation. The desired effect is affected by the type of HDPE added, the 
degree of dispersion of the HDPE into the polymer melt, and the 
crystallization conditions during the film casting step. It is highly 
desirable to use a [Hydrocarbon resin+HDPE] masterbatch formulation which 
is much less sensitive to film casting conditions than the formulation of 
Example 2. 
EXAMPLES 14-17 
In Example 14, a blend consisting of [50% REGALREZ 1139 hydrocarbon 
resin+15% ALATHON H6611 HDPE (Lyondell)+35% ESCORENE 4292 PP] was melt 
compounded and extruded into pellet form in the same fashion as the 
concentrate products of Examples 1 and 2. 
In Example 15, a similar concentrate blend was made except that ALATHON 
H5121 was the HDPE type added at a 15% level. 
Example 16, was a similar masterbatch containing 12.50i ALATHON H5234 HDPE 
while in Example 17 the masterbatch contained 12.5% Alathon H5618 HDPE. 
Blends represented by Examples 14 to 17 exhibited faster solidification of 
the extruded strand than the blend without HDPE, represented by Example 1, 
and both could be pelletized more efficiently. These types of HDPE are 
injection molding grades of polymer, and differ from the M6210 grade of 
Example 2 as described below. 
______________________________________ 
HDPE 
REGALREZ Melt Ind 
HDPE 
1139 (ASTM D- 
Density 
Example 
Content HDPE Content 1238) (g/cm.sup.3) 
______________________________________ 
2 50% 15% Alathon M6210 
1.0 0.962 
14 " 15% Alathon H6611 
11.0 0.966 
15 " 15% Alathon H5112 
12.0 0.951 
16 " 12.5% Alathon H5234 
34.0 0.952 
17 " 12.5% Alathon H5618 
18.0 0.956 
______________________________________ 
M6210 grade is a higher MW extrusion grade HDPE. The higher MW can 
negatively affect the ability of the polymer to be uniformly dispersed in 
a blend and it can slow the crystallization of the dispersed HDPE in such 
a blend under fast cooling conditions as when thin cast films are made. 
EXAMPLES 18-25 
In Example 18 (comparative), a 2 mil thick cast film was prepared from 
ESCORENE 4292 polypropylene in the same manner as the films of Examples 4 
to 7 by casting the melt onto casting rolls cooled by 50.degree. C. water. 
In Example 19 (comparative), a film was prepared in a similar manner as 
Example 18 from a blend of ESCORENE 4292 PP with 7% of the 50% REGALREZ 
1139 hydrocarbon resin concentrate described in Example 1B. 
In Example 20, a cast PP film was prepared according to Example 18 from 
ESCORENE 4292 PP with 7% of the masterbatch of Example 14, containing 50% 
REGALREZ 1139+15% ALATHON H661 HDPE. 
In Example 21, a similar film was prepared from a blend of ESCORENE 4292 PP 
with 7% of the masterbatch of Example 15 containing 50% REGALREZ 1139+15% 
ALATHON H5112 HDPE. Tensile properties of these cast films were measured 
as listed in the table below. It can be noted that the films containing 
REGALREZ 1139 hydrocarbon resin exhibited significantly higher tensile 
modulus while the films made from the masterbatches containing ALATHON 
H6611 or H5112 HDPE in addition to REGALREZ 1139 hydrocarbon resin 
exhibited even higher modulus values along with higher tensile yield 
stress values. 
In Examples 22 to 25 cast films were prepared in an identical fashion as 
the films of Examples 18 to 21 except that the water to the casting roll 
was 40.degree. C. instead of 50.degree. C. The tensile properties of these 
films were measured and compared to the values of the previous Examples in 
the table below. The lower casting roll temperature causes the treated 
melt to crystallize at a lower temperature and reduces the ultimate level 
of crystallinity. This effect in turn leads to lower tensile modulus and 
yield stress values as measured in Examples 22 to 25. In Example 24, 
containing ALATHON H 6611 HDPE in addition to 3.56 REGALREZ 1139, the cast 
film retained the highest modulus and yield stress values while the film 
of Example 25, containing ALATHON H5112 HDPE, exhibited somewhat lower 
values. The film of Comparative Example 23 containing 3.5% REGALREZ 1139 
with no added HDPE, exhibited a smaller increase in tensile modulus and 
yield stress relative to film made from 100% ESCORENE 4292 PP (Comparative 
Example 22) than the films additionally containing HDPE. In these previous 
Examples the addition of REGALREZ 1139 stiffened up the cast polypropylene 
firms, while the films additionally containing 1.05% HDPE were even 
stiffer. The influence of the HDPE is likely a synergistic effect on the 
crystallization of the polypropylene during the film casting step. Alathon 
H6611 which is a highly crystalline HDPE (0.966 density) was particularly 
effective in this application. 
__________________________________________________________________________ 
Modulus 
Yield Stress 
Cast 
Film 
% Haze 
(Kpsi) 
(Kpsi) 
Example 
Additive 
Temp. 
Gauge 
RR-1139 
% HDPE 
(%) 
MD/TD 
MD/TD 
__________________________________________________________________________ 
18 -- 50.degree. C. 
1.9 mil 
-- -- 7.8 
106/112 
2.95/3.00 
(comp.) 
19 7% . 1B 
" 2.0 3.5 -- 6.9 
127/125 
3.19/3.07 
(comp.) 
20 7% . 14 
" 1.9 3.5 1.05 5.9 
133/138 
3.42/3.48 
21 7% . 15 
" 1.9 3.5 1.05 5.5 
136/134 
3.46/3.38 
22 -- 40.degree. C. 
2.0 -- -- 4.3 
100/98 
2.76/2.64 
(comp.) 
23 7% . 1B 
" 1.9 3.5 -- 2.4 
113/115 
2.93/2.80 
(comp.) 
24 7% . 14 
" 2.0 3.5 1.05 2.5 
133/133 
3.34/3.21 
25 7% . 15 
" 2.0 3.5 1.05 2.6 
120/120 
3.10/3.05 
__________________________________________________________________________ 
EXAMPLES 26-33 
In Examples 26 to 29 cast PP films were made according to the procedure of 
Examples 18 to 21 except that Amoco 82-6721Y polypropylene was used and 
the casting roll water was 35.degree. C. 
In Examples 30 to 33 cast PP films were made according to the previous four 
examples except that the casting roll water was increased to 42.degree. C. 
The 82-6721Y polypropylene is a 7.5 g./10 min. MFR grade made by Amoco for 
cast PP film applications. Properties measured for these films are listed 
in the table below. 
__________________________________________________________________________ 
Film Modulus 
Yield Stress 
Cast 
Gauge 
% Haze/Gloss 
(Kpsi) 
(Kpsi) 
Example 
Additive 
Temp. 
(ml) 
RR-1139 
% HDPE 
(%) MD/TD 
MD/TD 
__________________________________________________________________________ 
26 -- 35.degree. C. 
1.9 -- -- 3.8/77 
112/111 
2.83/2.83 
(comp.) 
27 7% . 1B 
" 1.8 3.5 -- 3.0/80 
115/124 
2.92/2.97 
(comp.) 
28 7% . 14 
" 1.8 3.5 1.05 5.1/81 
144/143 
3.36/3.38 
29 7% . 15 
" 1.8 3.5 1.05 4.6/82 
137/138 
3.21/3.27 
30 -- 42.degree. C. 
2.0 -- -- 6.1/71 
113/111 
2.93/2.93 
(comp.) 
31 7% . 1B 
" 2.0 3.5 -- 5.7/70 
124/126 
3.06/3.11 
(comp.) 
32 7% . 14 
" 1.7 3.5 1.05 4.6/81 
151/148 
3.62/3.59 
33 7% . 15 
" 1.7 3.5 1.05 4.8/79 
139/140 
3.43/3.36 
__________________________________________________________________________ 
The cast PP films containing only REGALREZ 1139 additive exhibited 
marginally higher yield stress and modulus values, while the films 
additionally containing 1.05% HDPE exhibited significantly higher values. 
Again ALATHON H6611 grade HDPE with a 0.966 density was particularly 
effective in combination with REGALREZ 1139 hydrocarbon resin for 
stiffening the cast PP film. 
EXAMPLES 34-43 
In Example 34 (comparative), a cast PP film was produced from Amoco 
82-6721Y polypropylene in a manner similar to Example 26 except that the 
casting roll water was set at 28.degree. C. 
In Example 35 (comparative), a film was made as in Example 34 except that 
7% of the REGALREZ 1139 masterbatch of Example 1B was blended with the 
polypropylene. 
In Example 36, a film was made similar to the previous Example where the 
masterbatch added is described by Example 14, containing ALATHON H6611 
HDPE in addition to the REGALREZ 1139. 
In Example 37, a film was made similar to the previous Examples where the 
masterbatch added is described by Example 16, containing 12.50% ALATHON 
H5234 HDPE in addition to the REGALREZ 1139. 
In Example 38, a film was made similar to the previous Examples where the 
masterbatch added is described by Example 17, containing 12.5% ALATHON 
H5618 HDPE in addition to the REGALREZ 1139. 
In Examples 39 to 43 cast PP films were prepared in the same fashion as the 
films of Examples 34 to 38 except that the temperature of the cooling 
water to the casting roll was increased to 50.degree. C. The tensile 
properties of the films prepared in these Examples are listed in the table 
below. 
__________________________________________________________________________ 
Film Modulus 
Yield Stress 
Cast 
Gauge 
% Haze/Gloss 
(Kpsi) 
(Kpsi) 
Example 
Additive 
Temp. 
(ml) 
RR-1139 
% HDPE 
(%) MD/TD 
MD/TD 
__________________________________________________________________________ 
34 -- 28.degree. C. 
1.3 -- -- 1.2/85 
102/105 
2.69/2.58 
(comp.) 
35 7% . 1B 
" 1.7 3.5 -- 0.9/90 
124/121 
3.08/3.01 
(comp.) 
36 7% . 14 
" 1.7 3.5 1.05 4.4/81 
134/130 
3.29/3.20 
37 7% . 17 
" 1.5 3.5 1.05 3.4/79 
132/137 
3.30/3.27 
38 7% . 18 
" 1.5 3.5 1.05 3.2/82 
126/132 
3.14/3.06 
39 -- 50.degree. C. 
1.5 -- -- 10.5/44 
124/125 
3.17/3.16 
(comp.) 
40 7% . 1B 
" 1.9 3.5 -- 13.0/60 
135/137 
3.34/3.26 
(comp.) 
41 7% . 14 
" 1.7 3.5 1.05 4.2/79 
179/169 
4.16/4.05 
42 7% . 17 
" 1.5 3.5 1.05 3.3/83 
158/158 
3.82/3.66 
43 7% . 18 
" 1.5 3.5 1.05 3.8/79 
175/165 
4.09/3.89 
__________________________________________________________________________ 
As noted in previous Examples, adding REGALREZ 1139 hydrocarbon resin to 
the polypropylene formulation increased the stiffness of the cast PP films 
prepared from the mixture, and incorporating low levels of HDPE 
synergistically increased the stiffness even further. Various grades of 
HDPE were used in Examples 34 to 43 to modify the mechanical properties of 
cast PP films with good effect under a range of film casting conditions. 
The HDPE materials were injection molding grades with lower molecular 
weight which allowed them to be more easily distributed into the 
polypropylene formulation, and allowed the material to crystallize more 
readily under fast cooling conditions. It is important that the HDPE 
incorporated in the hydrocarbon resin masterbatch can modify the 
properties of cast polypropylene film even when the film gauge is thin or 
the casting temperature is at the low end of typical film casting 
conditions. 
EXAMPLES 44-46 
In Example 44 a REGALREZ 1139 masterbatch formulation consisting of 40% 
REGALREZ 1139 hydrocarbon resin +20% ALATHON H6611 HDPE+40% ESCORENE 4292 
PP was melt blended and pelletized in the fashion described in Examples 14 
to 17. 
In Example 45 a similar masterbatch containing 40% REGALREZ 1139 
hydrocarbon resin+40% ALATHON H6611 HDPE+20% ESCORENE 4292 PP was 
prepared. 
In Example 46 a masterbatch was prepared similar to Examples 45 and 46 by 
combining 30% ALATHON H6611 HDPE with 70% ESCORENE 4292 PP. 
It was noted that masterbatch formulations containing high levels of 
hydrocarbon resin solidified slowly due to the slower crystallization rate 
of the blends containing the amorphous resin. It was likewise noted that 
adding HDPE to these hydrocarbon resin masterbatch formulations caused the 
molten blend to solidify and stiffen up faster, allowing the masterbatches 
containing HDPE to be pelletized more efficiently during compounding. This 
effect is related to the effect of the HDPE on the crystallization rate of 
the hydrocarbon resin masterbatch formulations. The crystallization 
properties of several REGALREZ 1139 and HDPE masterbatch formulations in 
polypropylene were measured by differential scanning calorimetry (DSC) 
where the polymer blends were cooled from the melt at 25.degree. C./minute 
down to ambient temperatures, the total heat of crystallization and peak 
crystallization temperature being measured by this method. The DSC 
crystallization properties of several REGALREZ 1139 masterbatch 
formulations with or without additional HDPE are listed in the table 
below. 
______________________________________ 
REGALREZ Heat of 
Peak 
1139 Crystal- 
Crystallization 
Content HDPE lization 
Temperature 
Example (%) Content (Joules/g) 
(.degree. C.) 
______________________________________ 
Alathon H6611 
-- 100% 192.8 105.5 
Alathon H5112 
-- 100% 141.5 106.8 
Escorene 4292 
-- -- 80.7 102.4 
PP 
1 (comp.) 50 -- 42.3 91.8 
14 50 15% 59.9 97.9 
15 50 15% 54.8 92.7 
-- 40 -- 49.6 95.3 
45 40 40% 92.6 112.6 
-- 40 60% 110.8 110.8 
______________________________________ 
Compared to polypropylene, HDPE exhibits a higher heat of crystallization 
and faster crystallization. The faster crystallization rate is indicated 
by the smaller degree of cooling below the peak melting point of the 
polymer required for crystallization to occur in HDPE as compoared to PP. 
In the REGALREZ 1139 masterbatches, those formulations containing HDPE in 
addition to REGALREZ 1139 hydrocarbon resin exhibited both a higher 
crystallization temperature and a higher heat of crystallization. Both 
effects contribute to the faster rate at which the HDPE modified 
hydrocarbon resin masterbatches crystallizes to the degree of stiffness 
needed to allow the material to be effectively pelletized. 
EXAMPLES 47-54 
In Example 47 (comparative), a cast film sample was prepared from Amoco 
10-6711 cast film grade polypropylene (7.5 g./10 min. MFR) according to 
the procedure used in Examples 4 to 7. In this Example the cooling water 
to he casting rolls during film preparation was held at 40.degree. C. 
In Example 48, a film was prepared in an identical manner to Example 47 
except that 6% of the masterbatch of Example 44 was added to the Amoco 
10-6711 PP. 
In Example 49, a cast film was prepared in a manner identical to the 
previous two Examples except that 6% of the masterbatch material of 
Example 45 was added to the polypropylene. 
In Example 50, cast film was produced in the same manner as the previous 
three examples except the 6% of the masterbatch of Example 46 was added. 
In Examples 51 to 54 cast Polypropylene films were produced in an identical 
manner to the films of Examples 47 to 50 except that ESCORENE 4292 was the 
polypropylene grade used. Composition and tensile properties for these 
film samples are listed in the table below. 
__________________________________________________________________________ 
Film Modulus 
Yield Stress 
PP Gauge 
RR-1139 Haze/Gloss 
(Kpsi) 
(Kpsi) 
Example 
Additive 
Temp. 
(ml) 
% % HDPE 
(%) MD/TD 
MD/TD 
__________________________________________________________________________ 
47 -- Amoco 
1.5 -- -- 4.3/76 
108/110 
2.82/2.83 
(comp.) 10- 
6711 
48 6% . 44 
Amoco 
1.5 2.4 1.2 5.4/78 
122/122 
3.18/3.21 
10- 
6711 
49 6% . 45 
Amoco 
1.5 2.4 2.4 4.4/78 
147/159 
3.84/4.05 
10- 
6711 
50 6% . 46 
Amoco 
1.5 -- 1.8 6.1/77 
110/115 
3.00/3.03 
10- 
6711 
51 -- Escore 
1.5 -- -- 3.6/73 
105/99 
2.87/2.79 
(comp.) ne 
4292 
52 6% 44 
Escore 
1.6 2.4 1.2 2.6/85 
129/136 
3.38/3.41 
ne 
4292 
53 6% . 45 
Escore 
1.5 2.4 2.4 2.7/83 
118/134 
3.27/3.39 
ne 
4292 
54 6% . 46 
Escore 
1.5 -- 1.8 3.0/76 
134/129 
3.65/3.49 
ne 
4292 
__________________________________________________________________________ 
In cast film grade Amoco 10-6711 polypropylene the masterbatch of Example 
45 which added an equal amount of REGALREZ 1139 hydrocarbon resin and 
ALATHON H6611 HDPE to the cast PP film composition was most effective in 
increasing the stiffness of the film. In the low MFR ESCORENE 4292 polymer 
the masterbatch of Example 46, containing H6611 HDPE but no hydrocarbon 
resin, was as effective as the [REGALREZ 1139+HDPE] masterbatches for 
increasing the modulus of the cast PP film. 
In these and all previous Examples the hydrocarbon resin and HDPE were 
blended into the polypropylene polymer during the extrusion of the polymer 
in the film casting process. To achieve the desired effect on mechanical 
properties, both hydrocarbon resin and HDPE must be properly dispersed in 
the masterbatch, and a satisfactory viscosity match between the 
masterbatch and polypropylene polymer exist to permit the masterbatch 
components to be satisfactorily dispersed into the polypropylene polymer 
during the film extrusion process. For this reason the molecular weight or 
MFR of the HDPE polymer is an important factor as is the MFR of the 
[Hydrocarbon resin+HDPE] masterbatch. Comparing the Examples in the 
previous table it is noted that adding the masterbatch containing H6111 
HDPE without REGALREZ 1139 hydrocarbon resin was more effective for 
increasing the stiffness of the lower MFR ESCORENE 4292 polymer (Example 
54) than the same masterbatch in the higher MFR Amoco polymer (Example 
50). In the higher MFR Amoco polymer the masterbatch compositions 
containing both REGALREZ 1139 hydrocarbon resin and HDPE were most 
effective for increasing stiffness (Examples 48 and 49), the masterbatch 
containing H6611 HDPE without REGALREZ 1139 hydrocarbon resin being only 
marginally effective (Example 50). In these Examples the hydrocarbon resin 
substantially increased the MFR of the masterbatch formulation. This 
effect is important because an important factor in the ultimate 
effectiveness of the masterbatch is the proper viscosity match between the 
masterbatch and the polypropylene polymer being modified which affects the 
ultimate distribution of the additives into the film. 
The enhanced stiffness of cast PP films modified with low levels of HDPE 
may result from the faster crystallizing HDPE in turn accelerating the 
crystallization rate of the PP in the modified formulation. When cast film 
is made the cooling rate is very rapid, and the polymer can be quenched to 
a temperature low enough to prevent further crystallization before the 
desired level of crystallinity is developed. Faster crystallization 
translates into a higher crystallinity level and higher modulus in the 
final cast PP film. The crystallization properties of polypropylene 
formulations modified with the [Hydrocarbon resin+HDPE] masterbatches of 
this invention can be measured by differential scanning calorimetry (DSC). 
Several modified PP formulations were analyzed by DSC where the materials 
were cooled from the melt to ambient temperatures at a 25.degree. C./min. 
rate while the heat of crystallization and peak crystallization 
temperature were measured. Crystallization properties of several PP 
formulations modified with ALATHON HG6611 HDPE with or without additional 
REGALREZ 1139 hydrocarbon resin are listed in the table below. 
______________________________________ 
Peak 
Crystal- 
REGALREZ Heat of 
lization 
Poly- 1139 Crystal- 
Temp- 
Ex- propylene Content HDPE lization 
erature 
ample Type (%) Content 
(Joules/g) 
(.degree. C.) 
______________________________________ 
47 Amoco 10-6711 
-- -- 88.4 107.6 
49 " 2.4 2.4% 90.0 112.1 
50 " -- 1.8% 91.6 111.4 
51 Escorene 4292 
-- -- 76.6 108.0 
53 " 2.4 2.4% 82.0 112.9 
54 " -- 1.8% 82.6 112.1 
______________________________________ 
Normally adding hydrocarbon resin to polypropylene reduces the peak 
crystallization temperature and reduces the heat of crystallization by the 
same percentage amount as the % of amorphous resin added. In the Examples 
listed in the previous table the hydrocarbon resin modified formulations 
containing ALATHON H661 HDPE exhibited both a higher heat of 
crystallization and higher peak crystallization temperature. Likewise 
polypropylene formulations modified with only H6611 HDPE exhibited the 
same effect. This effect can facilitate the development of higher levels 
of crystallinity in cast PP films where the ultimate crystallization level 
is strongly influenced by the rapid cooling occurring during the film 
casting process. 
EXAMPLES 55-58 
In Example 55, a cast Polypropylene film was prepared from HD642H 
polypropylene, a cast film grade of polymer manufactured by Borealis, 
(Copenhagen, Denmark). The film was cast according to the procedure of 
Example 4 where the polymer was extruded onto a chill roll having a 
50.degree. C. surface temperature, and the casting speeds were adjusted to 
produce cast film nominally 1.5 mils thick. In Example 56 a film was 
produced in a manner similar to Example 55 except that the polymer feed 
contained 7% of a REGALREZ 1139 hydrocarbon resin/polypropylene 
concentrate, made according to Example 1B except that the concentration of 
REGALREZ 1139 in the blend was reduced from 50% to 40%. In Example 57 a 
cast PP film was made identical to the previous two Examples except that 
7% of the masterbatch of Example 44 was blended with the Borealis polymer. 
In Example 58 a similar film was made where 7% of the masterbatch of 
Example 45 was blended with the Borealis polymer. 
The tensile properties and barrier properties were measured for these cast 
films. The composition of each film and its corresponding properties are 
listed in the table below for comparison. 
______________________________________ 
Example 
Example Example Example 
55 56 57 58 
______________________________________ 
BOREALIS HD642H PP 
100 97.2 95.8 94.4 
REGALREZ 1139 resin 
-- 2.8 2.8 2.8 
ALATHON H6611 
-- -- 1.4 2.8 
HDPE 
MB Type -- Ex. 1B Ex. 44 Ex. 45 
Tensile Modulus, 
109/108 126/126 146/150 
154/159 
kpsi, MD/TD 
Yield Stress, kpai, 
3.07/3.05 
3.24/3.21 
3.81/4.06 
3.92/4.07 
MD/TD 
Haze (%) 9.4 6.6 5.1 4.4 
45.degree. Gloss (%) 
58 66 70 73 
Moisture Vapor 
9.86 9.08 7.10 6.77 
Transmission 
(g-mil/sq. m-day), 
100.degree. F., 90% 
RH 
O.sub.2 Permeability 
8840 8630 6700 6730 
@ 23.degree. C. 
(cc-mil/sq. m-day- 
atm.) 
______________________________________ 
Examples 57 and 58 made with hydrocarbon resin masterbatch compounds 
additionally containing HDPE exhibited tensile modulus and yield strength 
substantially higher than for the polypropylene film containing no added 
hydrocarbon resin, and also substantially higher than the values for the 
film containing 2.8% REGALREZ 1139 but no HDPE. Likewise the films into 
which HDPE was incorporated along with REGALREZ 1139 by using 
masterbatches of Examples 44 and 45 exhibited substantially better 
moisture and oxygen barrier properties than comparative films containing 
no HDPE. The novel formulations of this invention provide a means to 
improve the barrier properties of polypropylene films. 
While the invention has been described in connection with certain preferred 
embodiments so that aspects thereof may be more fully understood and 
appreciated, it is not intended to limit the invention to these particular 
embodiments. On the contrary, it is intended to cover all alternatives, 
modifications and equivalents as may be included within the scope of the 
invention as defined by the appended claims.