Polyolefin-extrusion coating compositions having good coatability, good adhesion to the substrate, and good chill roll release

Disclosed is a novel polyethylene composition that is a blend of a polyethylene component having defined properties, a specific quantity of a defined tackifying resin and a very specific minute quantity of a unique amide of a fatty acid. The novel composition can be used in a process for extrusion coating at high speeds and relatively low extrusion coating temperatures with good adhesion to the substrate and dramatically improved chill roll release.

FIELD OF THE INVENTION 
This invention relates to polyethylene compositions useful for low 
temperature extrusion coating. The present invention also relates to 
extrusion coating processes that are conducted at relatively low 
temperatures and fast line speeds that provide good adhesion to the 
substrate and good chill roll release. 
BACKGROUND OF THE INVENTION 
Extruding a coating of a polyolefin or blends of polyolefins onto a 
substrate, such as paper or aluminum foil, to form an extrusion coated 
substrate, is well known in the art. Extruding multiple layers of polymers 
including polyolefins as well as other materials in a process known as 
co-extrusion is also well known. Various polyethylenes and blends of 
polyethylenes have been used widely as extrusion coating compositions. 
Such materials have also been used in coextrusion processes as the layer 
against the substrate so as to adhere the coating to the substrate. 
Unfortunately, the use of polyethylene-based coatings has several 
drawbacks. For example, such materials frequently lack the desired level 
of adhesion to typical extrusion coated substrates, especially when 
extrusion coating is carried out at low temperatures and/or at extremely 
high coating speeds. In addition, polyethylene-based coatings typically 
require extrusion coating temperatures that generate excessive odor and 
are not compatible, in co-extrusions, with some heat sensitive polymers. 
Low temperature extrusion coating processes are useful when applying 
coextrusions with other polymers which are temperature sensitive. Low 
temperature extrusion coating processes are also useful when employing 
substrates which are temperature sensitive. Low temperature extrusion 
coating processes are also useful when applying polymeric coatings which 
contain additives which are temperature sensitive. Standard extrusion 
coating materials, particularly, polyethylene employed at low extrusion 
temperatures, are not capable of adhering to the substrate with the 
desired degree of adhesion. 
High extrusion coating speeds are desirable so as to enable economically 
attractive operation of extrusion coating equipment. High extrusion 
coating speeds are also desirable so as to permit the preparation of very 
thin extrusion coatings. 
Attempts to improve the adhesion to the substrate and coating speeds for 
extrusion and coextrusion are disclosed in U.S. Pat. No. 5,112,424, 
copending application Ser. No. 578,036 filed Sep. 5, 1990, now abandoned, 
and copending application Ser. No. 681,801 filed April 5, 1991, now 
abandoned These compositions and processes improve the adhesion of 
particular polyethylene compositions to the substrate by the addition of 
particular tackifying resins. To accomplish this good adhesion to the 
paper substrates, a high loading of up to 15 weight percent of tackifier 
is sometimes required. The tackifier, while promoting adhesion to the 
substrate, also increases the adhesion to the chill roll surface in 
extrusion coating operations, particularly when using a high gloss chill 
roll surface. The adhesion to the chill roll provides poor chill roll 
release. Sometimes the adhesion forces between the tackified composition 
and the chill roll exceed the adhesion forces between the tackified 
composition and substrate, and the polyethylene is pulled away from the 
substrate as the coated structure is pulled from the chill roll surface. 
Sometimes the adhesion force between the tackified polyethylene 
composition and substrate are so high that a destructive bond at the 
interface is formed while adhesion forces between the tackified 
polyethylene composition and chill roll are also high resulting in the 
substrate, when made of paper, being ruptured internally as the coated 
structure is pulled from the chill roll. In either case, poor bond between 
the coating and substrate or substrate rupture is undesirable. 
U.S. Pat. No. 4,526,919 discloses the use of fatty acid amides containing 
16 to 40 carbon atoms as chill roll release agents in polypropylene 
extrusion coating. 
It would be very desirable to be able to reduce the adhesion between the 
tackified polyethylene composition and chill roll without detracting from 
the adhesion forces required to bond the polyethylene to the substrate at 
low temperature extrusion coating. It would also be very desirable to be 
able to reduce this adhesion to the chill roll while maintaining the 
polyethylene's good surface qualities such as flame acceptance, corona 
priming, and heat seal ability. 
SUMMARY OF THE INVENTION 
The extrusion coating composition of the present invention comprises: 
(a) a polyethylene component having a melt index in the range of about 2 up 
to 100 dg per minute at 190.degree. C. and having a sufficiently broad 
molecular weight distribution so that the resulting composition is capable 
of being extrusion coated at a temperature in the range of 175.degree. C. 
up to 290.degree. C., 
(b) about 2 to 20 weight percent of a tackifying resin having a ring and 
ball softening point (RBSP) in the range of about 100.degree. up to 
140.degree. C., and 
(c) about 0.03 to 0.07 weight percent of the fatty acid amide, erucamide. 
The process according to the present invention for the low temperature 
extrusion coating of a substrate with a polyethylene film having a 
thickness of at least about 0.0075 mm comprises; applying the composition 
above to at least one surface of a substrate by extrusion coating at a 
temperature in the range of about 175.degree. to 290.degree. C.

DETAILED DESCRIPTION OF THE INVENTION 
The applicants have unexpectedly discovered that a unique fatty acid amide 
that, when added at a critical level to a unique polyethylene system 
containing a tackifying resin (tackifier) provides excellent chill roll 
release without detracting from the adhesion of the polyethylene system to 
the substrate. Chill roll release is freely obtained with the use of the 
critical amount of erucamide and the integrity of the surface and 
structure of the extrusion coated article is maintained. 
All of the tackifier-containing compositions described herein tend to 
exhibit chill roll sticking at all extrusion coating melt temperatures. 
Chill roll sticking worsens as more tackifier is added. Normally, for 
hard-finished paper substrates such as clay-coated board and 
machine-glazed paper, high amounts of tackifier are needed to effect good 
adhesion between the substrate and polyethylene (about 10% tackifier). At 
this high loading of tackifier, chill roll sticking is aggravated, and the 
paper substrates tend to delaminate or rupture internally as the 
polyethylene coating is peeled from the chill roll during the extrusion 
coating process. 
Unexpectedly, a small, yet critical quantity, of erucamide, between 300 and 
700 parts per million (ppm), was found to provide the best chill roll 
release, better than the lesser amount of 250 ppm and the greater amount 
of 1,000 ppm, in the presence of tackifier. Surprisingly, other fatty acid 
amides, and calcium stearate, were totally ineffective as a chill roll 
release agent for polyethylene in the presence of a tackifier. Also, 
surprising was the fact that erucamide fails to provide good chill roll 
release to a pure polyethylene system, i.e. without a tackifier. The 
tackifier's presence is required for the erucamide to effect good chill 
roll release for polyethylene, providing a synergistic interaction between 
tackifier and erucamide. 
The erucamide is a 22-carbon unsaturated, primary amide and can be 
purchased from Humko Chemical under the name of KEMAMIDE E. During the 
extrusion coating process the erucamide, in combination with polyethylene 
and tackifier, permits free release of the polyethylene coating from the 
chill roll at the specified quantities. The amount of erucamide used in 
the composition of the present invention varies from about 0.03 to 0.07 
weight percent, more preferably about 0.04 to 0.06 weight percent with 
about 0.05 weight percent erucamide being most preferred. 
The process according to the present invention for the low-temperature 
extrusion coating of a substrate with a polyethylene film having a 
thickness of at least about 0.0075 mm comprises; applying the inventive 
composition to at least one surface of said substrate by extrusion coating 
at a temperature in the range of 175.degree. to 290.degree. C. The process 
according to the present invention is preferably conducted at a 
temperature of about 200.degree. to 260.degree. C., with a temperature of 
about 240.degree. to 250.degree. C. being most preferred. 
In the process according to the present invention the composition that is 
extrusion coated onto a substrate also contacts a chill roll and has a 
sound level at the chill roll release point that is significantly reduced 
when compared to an identical process and composition except without the 
presence of the erucamide. This reduction of the sound level at the chill 
roll release point is at least 5 decibels less, preferably at least 10 
decibels less, with a reduction in sound level of at least 15 decibels 
less being most preferred. 
Polyethylene compositions useful in the practice of the present invention 
are materials having a melt index at 190.degree. C. falling in the range 
of about 2 up to 100 decigrams per minute. Preferred polyethylene 
components are materials having a melt index falling in the range of about 
20 up to 80 decigrams per minute; with materials having melt index falling 
in the range of about 30 up to 80 being most preferred. 
Polyethylene materials useful in the practice of the present invention are 
typically low density materials. Polyethylenes having densities in the 
range of about 0.913 to 0.926 are presently preferred materials. 
It is desirable that the polyethylene materials employed in the practice of 
the present invention have a sufficiently broad molecular weight 
distribution so that the resulting composition is capable of being 
extrusion coated at temperatures in the range of about 175.degree. to 
290.degree. C. Those of skill in the art recognize that materials of very 
narrow molecular weight distribution will not be suitable for the desired 
extrusion coating application, while materials having intermediate, up to 
very broad molecular weight distributions, will be more suitable for the 
desired extrusion coating application. Typically, materials employed in 
the practice of the present invention will have a polydispersity index, 
i.e., ratio of weight average molecular weight (Mw) to number average 
molecular weight (Mn), of at least about 7, preferably about 10 to 20 with 
a polydispersity index of about 12 being most preferred. 
It is also desirable that the polyethylene materials employed in the 
practice of the present invention have a minimum melting point onset 
temperature of at least about 95.degree. C., as measured by differential 
scanning calorimetry (DSC). Materials having such melting properties 
provide excellent handling characteristics for extrusion coating 
applications. 
A DSC curve for an exemplary composition containing polyethylene and 
tackifier is illustrated in U.S. Pat. No. 5,112,424 the disclosure of 
which is incorporated herein by reference in its entirety. The composition 
employed to obtain this DSC curve is a material having a melt index of 
about 32 dg/min and a density of about 0.92 g/cc. This material was 
prepared by blending 90 weight % of a low density polyethylene having a 
melt index of about 20 dg/min with 10 weight % of NIREZ 1135 tackifying 
resin. The sample has an onset melting point (determined by extrapolation) 
of 96.1.degree. C., with a peak melting point of about 105.degree. C. 
Polyethylene materials useful in the practice of the present invention can 
be prepared by polymerizing relatively high purity ethylene in a stirred 
reactor at pressures above about 1,000 atmospheres and temperatures above 
about 200.degree. C., using a peroxide-type of catalyst, such as, for 
example, di-tertiarybutyl peroxide. Lower purity ethylene containing inert 
materials such as methane, ethane, carbon dioxide, and the like, may be 
introduced into the ethylene feed to control the purity thereof. 
Publications to which the reader is directed for further general details 
on the preparation of suitable low density polyethylenes are the test 
Polythene by Renfrew and Morgan, at pp. 11-17 and the article in Petroleum 
Refiner (1956) by Thomasson, McKetta and Ponder, found at p. 191. 
The tackifying resins useful in the compositions of this invention have 
Ring and Ball softening points (RBSP) of about 100.degree. to 140.degree. 
C., more preferably about 125.degree. to 140.degree. C., with a RBSP of 
about 135.degree. C. being most preferred. 
Suitable preferred tackifying resins are the rosin ester resins and the 
terpene polymers such as the polymeric, resinous materials including the 
dimers as well as high polymers obtained by polymerization and/or 
copolymerization of terpene hydrocarbons such as the alicyclic, 
monocyclic, and bicyclic monoterpenes and their mixtures, including 
allo-ocimene, carene, isomerized pinene, pinene (e.g. NIREZ (available 
from Reichhold Chemical), a polymer of .beta.-pinenes), dipentene, 
terpinene, terpinolene, limonene, terpentine, a terpene cut or fraction, 
and various other terpenes. Particularly useful resin esters are the amber 
colored pentaerythritol ester of rosin having an acid number of about 7 to 
16 and a Ring and Ball softening point of about 100.degree. C. to 
110.degree. C., such as the Zonester family of products available from 
Arizona Chemical. One such resin is the pentaerythritol ester of tall oil 
rosin having a Ring and Ball softening point of 100.degree. C. and an acid 
number of about 11. 
The quantity of tackifying resin employed in the invention compositions can 
vary widely, typically falling within the range of about 2 up to 20 weight 
percent, based on the weight of the total composition. The coating 
thickness also influences the required amount of tackifying resin, i.e. 
the thicker the coating the lower the amount of tackifying resin is 
needed. Preferred quantities of tackifying resin fall within the range of 
about 7 up to 15 weight percent with an amount of about 8 to 10 weight 
percent being most preferred at a coating thickness of about 0,001 inches 
(0.025 mm). These quantities are preferred because at these levels of 
tackifier, maximum adhesion per quantity of tackifier added is achieved. 
Thus, at lower levels of tackifier, reduced adhesion is observed while 
little added benefit is obtained. With higher levels of tackifier, chill 
roll release problems are further aggravated. 
As noted above, the invention compositions can optionally further contain 
in the range of about 25 up to 200 parts per million of a transition metal 
pro-oxidant. Transition metal compounds contemplated for use in the 
practice of the present invention are salts formed by combining transition 
metals such as cobalt, manganese, and copper with organic, acids of 
sufficiently high molecular weight to give salts soluble in the polymer 
blends employed. 
As employed herein, the term "transition metal" is intended to include 
elements having greater than 8, and less than 18, electrons in the outer 
shell of the ionic species. Transition metals are thus usually capable of 
electron transitions between their outer shells. Thus, the variable 
valency states which result render these elements capable of inducing 
oxidation reactions. In practice, those transition elements which are 
highly toxic and/or radioactive are extremely rare and costly, and thus 
are not normally encountered in industrial use as oxidation catalysts. 
More typically encountered transition metals whose salts and complexes are 
useful for such applications include cerium, zinc, copper, silver, nickel, 
cobalt, iron, manganese, chromium, and vanadium. These elements can be 
used in the form of such salts as posses an adequate level of solubility 
in the polymer melt, typically including such forms as stearates, oleates, 
behenates, miristates, erucates, lineoleates, naphthanates, or complexes 
such as acetonyl acetates, 8-hydroxyquinolinates, metal amine salt 
complexes, and the like, as well as mixtures of any two or more thereof. 
Preferred quantities of pro-oxidant, when employed, fall in the range of 
about 100 up to 150 parts per million, based on the total weight of 
polymer compositions. 
In accordance with an alternative embodiment of the present invention, 
there may further be included in the invention compositions up to about 10 
weight percent of a biodegradable organic polymer. Compounds contemplated 
by the term "biodegradable organic polymer" include polymeric materials 
which are themselves intrinsically sensitive to direct enzyme chain 
scission in the presence of micro-organisms which occur profusely in the 
environment. Exemplary materials contemplated by the above definition 
include polymeric carbohydrates such as corn starch. 
When employed, quantities in the range of about 1 up to 10 weight percent 
of biodegradable organic polymer are typically employed. Preferably, in 
the range of about 4 up to 6 weight percent of biodegradable organic 
polymer will be employed. 
The compositions of this invention may be prepared in various ways such as 
dry blending and then passing through a compounding extruder, compounding 
on a milling roll or in a Banbury mixer or by fusion. Any method whereby 
the components can be blended together will produce the desired blend. For 
example, pellets of each polymer can be blended mechanically and the blend 
then fed to an extruder where it is fused and extruded. 
Additives, stabilizers, fillers and the like can be added to the 
compositions of the present invention. Such materials can be present in 
the components forming the polymer blend, or may be added when the 
polymers are blended to form the extrusion coating composition. 
A wide variety of additional extrudable compositions are useful in 
coextruding with the present invention as long as the composition of the 
present invention is coextruded as the outer layer in contact with the 
chill roll. Examples of coextrusion compositions include: 
polyethylenes having a melt index different than the melt index of said 
first polyethylene component, 
polyethylenes having a density different than the density of said first 
polyethylene component, 
polyethylenes modified with polymer additives, 
polypropylene homopolymers, comonomers, copolymers, and terpolymers, 
optionally modified with polymer additives, 
polyethylene comonomers, copolymers and terpolymers, including extrudable 
ionomers, optionally modified with polymer additives, 
extrudable polymers of higher olefins having in the range of 4 up to 8 
carbon atoms, optionally modified with polymer additives, 
extrudable polyamides, optionally modified with polymer additives, or 
extrudable polyesters, optionally modified with polymer additives; 
as well as mixtures of any two or more thereof. 
Each of the above coextrusion polymeric compositions can be modified by 
addition of polymer additives, such as, for example, slip agents, 
antiblock agents, pigments (organic or inorganic), stabilizers (e.g., 
thermal, ultraviolet, flame retardants, antioxidants, and the like), 
starch based additives to impart biodegradability to the composition, 
fillers, and the like. Such additives can be physically blended with said 
polymers, chemically incorporated by copolymerization, grafting, or the 
like, and so forth. 
Polypropylene materials contemplated for use in the coextrusion practice of 
the present invention include polypropylene homopolymer as well as 
copolymers and terpolymers having incorporated therein such co-monomers as 
ethylene, maleic anhydride, 1-butene, 1-hexene, 4-methyl-1-pentene, 
hydroxyethyl methacrylate, acrylic acid, N-vinyl pyrrolidone, and the 
like, as well as mixtures of any two or more thereof. 
Propylene polymers contemplated for use in the coextrusion practice of the 
present invention also include a predominantly polypropylene-containing 
polymer backbone which has been further modified by such techniques as 
grafting with one or more of the co-monomers set forth above. 
Polyethylene materials contemplated for use in the coextrusion practice of 
the present invention include polyethylene homopolymer as well as 
copolymers and terpolymers having incorporated therein such co-monomers 
as: 
vinyl acetate, 
vinyl alcohol, 
carbon monoxide 
maleic anhydride, 
ethyl methyl acrylate, 
ethyl ethyl acrylate, 
ethyl methyl pentene, or 
ethyl acrylic acid, 
and the like, as well as mixtures of any two or more thereof. As in the 
case with propylene-containing polymers, ethylene polymers contemplated 
for use in the practice of the present invention include a predominantly 
ethylene-containing polymer backbone which has been further modified by 
such techniques as grafting with one or more of the co-monomers set forth 
above. 
Polymers of higher olefins contemplated for use in coextrusion practice of 
the present invention include poly(1-butene), poly(4-methyl-1-pentene), 
and the like. 
Polyesters contemplated for use in the coextrusion practice of the present 
invention include polyethylene terephthalate (PET), polybutylene 
terephthalate (PBT), polycyclohexanedimethanol terephthalate (PCT), and 
the like, as well as co-polyesters thereof. 
Extrusion coating and multi-layer extrusion coating processes are well 
known in the art and are well within the skill of the artisan. See, for 
example, U.S. Pat. No. 4,152,387, incorporated by reference in its 
entirety. Those of skill in the art can readily apply the compositions 
disclosed herein to such processes. 
The laminate structure produced in the coextrusion process can have the 
first polyethylene-containing component present as the substrate contact 
layer, as the exterior barrier layer, or, where two or more polymeric 
materials are coextruded with the polyethylene-containing composition, the 
polyethylene layer can be positioned as an adhesive tie-layer between the 
two or more additional extrudable compositions. 
Substrates contemplated for use in the practice of the present invention 
include papers, paperboards, fibers, polymeric materials, metal foils, and 
the like. Polymeric substrates include polyolefins or ethylene-vinyl 
alcohol copolymers or functionally-modified derivatives thereof, 
polyamides or functionally modified polyamides, and the like. 
The invention compositions, upon application to substrate by extrusion 
coating techniques, form a destructive bond, i.e., the substrate-coating 
bond is sufficiently strong that efforts to separate the coating from the 
substrate cause destruction of either the coating or the substrate. 
This invention can be further illustrated by the following examples of 
preferred embodiments thereof, although it will be understood that these 
examples are included merely for purposes of illustration and are not 
intended to limit the scope of the invention unless otherwise specifically 
indicated. 
EXAMPLES 
The following examples show the criticality of a unique fatty acid amide, 
erucamide, in effecting good chill roll release for a tackifier-modified 
polyethylene in the extrusion coating process. The erucamide is compared 
to other additives: stearyl erucamide, behenamide, oleamide, stearamide, 
and calcium stearate. 
The examples were extrusion coated under the following conditions: 
Chill Roll Surface Finish 4 to 6 rms (micro-inches) 
Extrudate Temperature Shown for Each Example 
Die Opening 0.020-inch 
Die Width 32-inch 
Extrusion Output Rate 16-lb/hr/inch of die width 
Die-to-Nip Distance 5-inch 
Laminator Speed Shown for Each Example 
All other conditions, unless noted, were essentially the same for all 
examples. 
In the extrusion coating process, as a polymeric coating is pulled from the 
metal chill roll, the sound intensity (chatter) generated at the release 
point is an indication of chill roll release. The lower the sound level, 
the better the chill roll release. A high sound level can also indicate 
substrate rupture and/or weak adhesion between polymer and substrate. 
During the extrusion coating of each example, sound level, monitored in 
decibels (dB), was measured at the chill roll release point using a Sound 
Level Meter, Model 1565-B, manufactured by General Radio, USA. In each 
case, the sound meter was set to "A" scale intensity to monitor the 
quality of chill roll release. 
EXAMPLE 1 
A 32-melt index polyethylene having a density of 0.916-g/cc and a 
polydispersity index of about 12, available from Eastman Chemical Co. 
(ECC) as TENITE 811A, containing 10 percent by weight of a tackifier, 
NIREZ 1135, was used to extrusion coat a paper substrate (40-lb bleached 
Kraft Paper) with the following observations: 
Extrudate Temperature 469.degree. F. (243.degree. C.) 
Sound Level 108-dB 
Adhesion to Substrate Good (Fiber Tear) 
Substrate Integrity Ruptured Internally 
Wrapped Chill Roll at 650-fpm (197-m/min) 
This example shows the problems caused by the presence of a tackifier in 
the extrusion coating of a polyethylene system. While adhesion to the 
substrate was excellent, the internal rupturing of the substrate made the 
product unfit for use. Chill roll sticking was noted by the high sound 
level of 108-dB. 
EXAMPLE 2 
A 2.5-melt index pure polyethylene having a density of 0.926-g/cc was 
modified with five (5) levels of Humko Chemical's erucamide (Humko is a 
division of Witco). Each modification was extrusion coated to-the same 
Kraft paper substrate at an extrudate temperature of 600.degree. F. 
(315.degree. C.). Coating speed was 400-fpm (121-m/min). The following 
were observed: 
______________________________________ 
Erucamide Level Sound Level 
______________________________________ 
0% 111-dB 
0.05% 110-dB 
0.075% 109-dB 
0.10% 108-dB 
0.125% 107-dB 
______________________________________ 
The addition of erucamide to a pure polyethylene system, i.e., one without 
a tackifier, provides some minor, but insignificant improvement in chill 
roll release. One would conclude from this example that erucamide, as a 
single additive, contributes little to the chill roll release of a pure, 
otherwise unmodified, polyethylene system. 
EXAMPLE 3 
The polyethylene, of Example 1, containing the tackifier was modified with 
five (5) levels of erucamide. Each modification was extrusion coated to a 
paper substrate at an extrudate temperature of 470.degree. F. (243.degree. 
C.) The following observations were noted: 
______________________________________ 
Erucamide Level 
Sound Level Comments 
______________________________________ 
0% 108-dB Stuck to Chill Roll 
at 650-fpm. Substrate 
ruptured internally. 
0.025% 112-dB Paper ruptured. 
No chill roll wrap. 
0.04% 97-dB Adhesion good. 
Substrate intact. 
0.05% 95-dB Adhesion good. 
Substrate intact. 
0.06% 97-dB Adhesion good. 
Substrate intact. 
0.075% 109-dB Adhesion unacceptable. 
Substrate intact. 
0.10% 107-dB Adhesion poor. 
Substrate intact. 
______________________________________ 
Unexpectedly, in the presence of the pinene tackifier, NIREZ 1135, the 
erucamide provides excellent chill roll release in the 0.04-0.06 weight 
percent range. Although NIREZ 1135 is the most preferred tackifier the 
erucamide would perform synergistically with the other aforementioned 
tackifiers having the required RBSP. 
EXAMPLE 4 
The 32-melt index polyethylene of Example 1, containing the tracker was 
modified with four (4) levels of a fatty acid amide, stearyl erucamide. 
Each modification was extrusion coated to the same Kraft paper substrate 
at an extrudate temperature of 470.degree. F. (243.degree. C.). The 
following observations were noted: 
______________________________________ 
Stearyl Erucamide 
Sound Level Comments 
______________________________________ 
0% 108-dB Stuck to Chill Roll 
at 650-fpm. Substrate 
ruptured internally. 
0.05% 115-dB Stuck to Chill Roll 
at 800-fpm. Substrate 
ruptured internally. 
0.10% 115-dB Stuck to Chill Roll 
at 800-fpm. Substrate 
ruptured internally. 
0.40% 104-dB No wrap of Chill 
Roll. Adhesion poor. 
Substrate intact. 
______________________________________ 
EXAMPLE 5 
Other fatty acid amides, specifically behenamide, oleamide, and stearamide 
were tested according to Example 4. Each of the fatty acid amides gave 
essentially identical results to those in Example 4. Under the same 
conditions shown above, they were no better than stearyl erucamide as 
chill roll release agents in the polyethylene system containing a 
tackifier. 
This example shows that (1) while the 0.4 weight percent loading of stearyl 
erucamide may have imparted good processability to the 
polypropylene-tackifier system cited in U.S. Pat. No. 4,526,919, it failed 
to permit good adhesion in a polyethylene-based system; (2) stearyl 
erucamide and other fatty acid amides are inferior to erucamide as chill 
roll release agents for tackifier-modified polyethylene systems; and (3) 
one must be critically selective of the fatty acid amide, and its 
concentration, when it is used as a chill roll release agent for a 
tackifier-modified polyethylene system in extrusion coating. 
EXAMPLE 6 
The 32-melt index polyethylene of Example 1 was modified with four (4) 
levels of a fatty acid salt, calcium stearate. Each modification was 
extrusion coated to the same Kraft paper substrate at an extrudate 
temperature of 470.degree. F. (243.degree. C.). The following observations 
were noted: 
______________________________________ 
Calcium Stearate 
Sound Level Comments 
______________________________________ 
0% 108-dB Stuck to Chill Roll 
at 650-fpm. Substrate 
ruptured internally. 
0.05% 113-dB Stuck to Chill Roll 
at 800-fpm. Substrate 
ruptured internally. 
0.10% 115-dB Stuck to Chill Roll 
at 800-fpm. Substrate 
ruptured internally. 
0.50% 112-dB No wrap of Chill 
Roll. Adhesion poor. 
Substrate intact. 
______________________________________ 
This example shows that (1) fatty acid salts most likely do not provide 
good chill roll release for a polyethylene-based system, and (2) calcium 
stearate is inferior to erucamide as a chill roll release agent. 
The graph in FIG. 1 shows the criticality and uniqueness of erucamide as a 
chill roll release agent for a polyethylene containing a tackifier used in 
extrusion coating.