A thermoplastic film is provided which is especially suited for use in stretch/cling applications such as, for example, the bundling, packaging and unitizing of foods and other goods. The film comprises a cling layer comprising (i) a polymer of at least ethylene and acrylate or vinyl acetate, blended with (ii) a compatible, non-migratory tackifier. The film may further comprise a non-cling layer comprising a thermoplastic material essentially free of tackifier, with or without an anticling (slip and/or antiblock) additive. Preferred thermoplastic materials include linear low density polyethylene and polypropylene.

FIELD OF THE INVENTION 
The present invention relates generally to thermoplastic films and, more 
particularly, to thermoplastic films having properties making them 
especially well suited for use as stretch/cling wraps in various bundling, 
packaging and palletizing operations. 
BACKGROUND OF THE INVENTION 
Stretch/cling films have found utility in a wide variety of fields 
including the bundling and packaging of food and other goods. One 
application of particular, but not limiting, interest to the present 
invention is in the bundling of goods for shipping and storage such as, 
for example, the bundling of large rolls of carpet, fabric or the like for 
shipping from the manufacturer to a retail outlet. An important subset of 
these bundling applications is in the containment and unitizing of pallet 
loads. 
The load of a pallet may be unitized or "bundled" by stretch-wrapping a 
film several times around the articles to be palletized. There exist a 
variety of stretch-wrapping techniques, two of which are commonly 
employed. In one technique, the loaded pallet is placed on a rotating 
turntable and the end of a continuous roll of film attached to the load. 
As the turntable rotates, the film is continuously wrapped around the 
pallet and load. Tension is applied to the film roll to cause the film to 
stretch as it is applied. 
Because the film is in a stretched condition, it is placed under 
considerable tension and will have a tendency to return to its original, 
unstretched state. This tension can cause the film to unravel from the 
wrapped pallet, thereby jeopardizing the integrity of the unitized load. 
It is desirable, therefore, that the film have cling properties to prevent 
unraveling of the film from the pallet. 
To impart cling properties to, or improve the cling properties of, a 
particular film, a number of well-known tackifying additives have been 
utilized. Common tackifying additives include polybutenes, terpene resins, 
alkali metal and glycerol stearates and oleates and hydrogenated rosins 
and rosin esters. The cling properties of a film can also be modified by 
the well-known physical process referred to as corona discharge. 
The use of tackifying additives ordinarily is not desirable. While 
tackification is known in the art to enhance cling in an olefin cling film 
relative to an untackified film, this property improvement is not 
typically seen in the stretched film, and cling can become unsatisfactory 
when the film is stretched. Furthermore, lack of compatibility between 
film and tackifier resin may cause blending difficulties during film 
manufacture, adversely affect optical properties of the film and enhance 
surface migration of the additive. Such migration can damage the wrapped 
goods and has been known to cause the collapse and/or telescoping of 
rolls. 
While "inner" surface cling in such film wraps is desirable, outer surface 
cling may be detrimental to the integrity of the load. Cling between 
adjacent wrapped pallets may cause tearing or puncturing of or other 
damage to the wrap as the pallets are transported. For this reason, it is 
desirable for the film to have slip or at least non-cling properties on 
its "outer" side to prevent this interpallet cling. Slip is defined in 
terms of coefficient of friction. In other words, it is desirable that the 
"outer" side of the film have a low coefficient of friction in contact 
with another object, particularly another like film. As with cling, slip 
can be imparted to the film or improved through the use of various 
well-known slip and/or antiblock additives including silicas, silicates, 
diatomaceous earths, talcs and various lubricants. Under highly stretched 
conditions, however, the coefficient of friction in the films tends to 
increase and even the slip additives may not provide the desired slip 
properties. 
The tension in the stretched film may also cause the film to be more 
susceptible to punctures and tears. It is, therefore, also desirable for 
the film, as a whole, to have good stretch, tensile, puncture resistance 
and tear resistance properties. 
Additionally, thermal stability of the various film components is important 
for the recycling of edge trim and film scrap generated in the various 
film production processes. 
A wide variety of thermoplastic polymers such as, for example, polyvinyl 
chloride, polyethylene, polypropylene and various polymers of ethylene and 
other comonomers, most notably vinyl acetate, have been used as 
stretch/cling films. These materials standing alone, however, suffer from 
a number of shortcomings. Most cannot be stretched to a great extent 
without adversely affecting their slip, tensile, tear resistance and 
puncture resistance properties. For the particular case of ethylene-vinyl 
acetate polymers, thermal stability becomes a problem on the reprocessing 
of trim and scrap. 
More recently, the use of multilayer films has gained popularity. With a 
multilayer film, one can obtain a stretch/cling wrap having cling 
properties on one side and slip properties on the other side. For example, 
U.S. Pat. No. 4,518,654 discloses a multilayer film having an A/B 
construction wherein the A side has cling characteristics and the B side 
has slip characteristics. In the aforementioned patent, the A side is said 
to comprise a polyethylene or an ethylene-monoolefin polymer, preferably 
linear low density polyethylene (LLDPE). To provide the LLDPE with the 
desired cling properties, a tackifying agent such as polyisobutylene 
(PIB), which migrates to the film surface or "blooms," is added to the 
polymer. The B side is said to comprise a low density polyethylene (LDPE) 
with an anticling additive added to impart the desired slip properties to 
the LDPE. This patent is hereby incorporated by reference herein for all 
purposes as if fully set forth. 
Other multilayer films comprising layers of the various aforementioned 
stretch/cling materials are disclosed in U.S. Pat. Nos. 3,508,944, 
3,748,962, 3,817,821, 4,022,646, 4,082,877, 4,147,827, 4,189,420, 
4,194,039, 4,303,710, 4,399,180, 4,364,981, 4,418,114, 4,425,268, 
4,436,788, 4,504,434, 4,588,650 and 4,671,987; U.K. Patent Application No. 
2,123,747; French Patent No. 2,031,801; and European Patent Application 
No. 0,198,091, all of which are also incorporated by reference herein for 
all purposes. These multilayer films are generally produced by one of a 
number of well-known coextrusion processes also disclosed in the 
aforementioned incorporated references. 
Many of the multilayer films, however, still suffer from shortcomings 
possessed by their individual layers. For instance, most do not possess 
desired cling properties, and have reduced cling when in a highly 
stretched state. Others do not possess a desirable combination of stretch, 
tensile, tear resistance, puncture resistance, optical and thermal 
stability properties. 
In European Patent Application No. 0,317,166 and previously mentioned U.S. 
Ser. No. 123,002, filed Nov. 19, 1987, both of which are hereby 
incorporated herein by reference, there is described a stretch/cling film 
having a cling layer of ethylene-acrylate copolymer. The film preferably 
avoids the use of a tackifying additive. 
Hot melt adhesives, containing a blend of (a) high density polyethylene or 
isotactic polypropylene, (b) a copolymer of ethylene and an alkyl ester of 
acrylic or methacrylic acid or vinyl acetate, (c) an ionomer resin and (d) 
a tackifier such as a terpene resin or a glyceryl ester of a rosin acid, 
are described in U.S. Pat. Nos. 4,337,298 and 4,367,113 to Karim et al. 
SUMMARY OF INVENTION 
The present invention resides in part in the discovery of a tackified 
thermoplastic film having excellent cling properties which are, quite 
surprisingly, improved not only in an unstretched condition, but also in a 
stretched state. Broadly, the present invention provides a stretch/wrap 
thermoplastic film comprising a cling layer and a second polymer layer 
adjacent the cling layer. The cling layer consists essentially of (i) a 
polymer of two or more monomers, wherein a first monomer comprises 
ethylene and a second monomer comprises an acrylate or vinyl acetate, and 
(ii) a compatible tackifier blended therewith, wherein the blend has a 
glass transition temperature of about 0.degree. C. or less. Miscibility of 
tackifier and polymer in the present invention surprisingly results in 
enhancement of cling properties in the highly stretched condition, rather 
than a substantial reduction in cling properties heretofore observed upon 
stretching the tackified stretch/cling films of the prior art. In 
addition, by careful selection of the tackifier, optical properties of the 
cling layer blend are not adversely affected. 
The present invention further provides a multilayer stretch/cling film 
having excellent cling properties on one side and excellent slip 
properties on an opposite side, wherein the cling properties are enhanced 
in a stretched state as well as an unstretched state. 
Still further, the present invention provides a multilayer stretch/cling 
film which, as a whole, possesses desirable stretch, tensile strength, 
puncture resistance, tear resistance, optical and thermal stability 
properties. 
The present invention also provides a method for producing a thermoplastic 
film having a cling layer opposite a second layer. The method comprises 
the step of coextruding into a film a polymer-tackifier blend having cling 
properties as a cling layer, with a second layer. The blend consists 
essentially of (i) a polymer of two or more monomers, wherein a first 
monomer comprises ethylene and a second monomer comprises an acrylate or 
vinyl acetate, and (ii) a compatible tackifier blended therewith, wherein 
the blend has a glass transition temperature of about 0.degree. C. or 
less. 
Finally, the present invention provides a process for using such 
stretch/cling film to bundle, package or unitize an article or a plurality 
of articles, and an article or plurality of articles so bundled, packaged 
or unitized. 
In accordance with the present invention, there is provided a thermoplastic 
film which comprises, in its overall concept, a cling layer comprising a 
polymer of two or more monomers and a compatible tackifier intimately 
blended therewith. A first monomer comprises ethylene and a second monomer 
comprises an acrylate or vinyl acetate. Such polymer shall generally be 
referred to as an ethyleneacrylate (or EA) polymer. 
The blend preferably has sufficient cling for utility as the cling layer in 
a stretch/cling film. More particularly, the EA polymer preferably 
comprises an acrylate or vinyl acetate content of between about 20% to 
about 40%, more preferably above about 24%, most preferably above about 
28%, by weight based upon the weight of the EA polymer. The tackifying 
additive preferably comprises from about 1% to about 30%, more preferably 
from about 5% to about 15%, by weight of the cling layer. The tackifier is 
preferably non-migratory, i.e. it is essentially retained in the cling 
layer, and when the second layer is a non-cling and/or core layer(s), such 
layer(s) is preferably essentially free of the tackifier. 
The thermoplastic film may further comprise a second cling layer opposite 
the first cling layer, but preferably comprises a non-cling layer, more 
preferably a slip layer, opposite the cling layer, the non-cling or slip 
layer comprising any suitable thermoplastic material such as, for example, 
polyethylene (including high density, low density and linear low density 
polyethylenes), polypropylene, etc. Particularly preferred is 
polypropylene. The non-cling side should, of course, be essentially free 
of the tackifier from the cling layer so that the non-cling layer retains 
its non-cling characteristics. In addition, the non-cling side may include 
one or more well-known anticling (slip and/or antiblock) additives, but 
the non-cling layer is preferably essentially free of such anticling 
additives. 
The thermoplastic film of the invention may be so constructed that a layer 
adjacent the first cling layer is a structural layer, and the second skin 
layer is positioned adjacent the structural layer. That is, the structural 
layer separates the first cling layer and the second layer. The second 
layer of the thermoplastic film may comprise a cling layer or a non-cling 
layer. In either case, the second layer may be a polyolefin. Preferably, 
when the second layer is a cling layer, it also comprises a blend of a 
polymer of 2 or more monomers and a compatible tackifier, wherein a first 
monomer comprises ethylene and a second monomer comprises an acrylate or 
vinyl acetate (EA). Where the third layer is a non-cling layer, it may 
include one or more of the well-known anticling (slip and/or antiblock) 
additives. 
The structural layer of the thermoplastic films having more than 2 layers 
comprises about 5 to 95%, preferably at least about 50%, more preferably 
at least about 70-80% of the weight of the film. The structural layer may 
comprise a polyolefin of suitable makeup for the purpose to which the film 
is to be applied, such as, for example, linear low density polyethylene 
which is common for strength and optical properties in unitizing 
applications of stretch/cling films. 
The thermoplastic film of the present invention may be produced utilizing 
any one of a number of well-known extrusion or coextrusion (in the case of 
multilayer films) equipment and processing conditions. In a multilayer 
film, the cling layer will preferably comprise from about 5% to about 95%, 
and the non-cling layer(s) will preferably comprise from about 95% to 
about 5%, of the total combined thickness of the film layers. 
Thermoplastic films produced in accordance with the present invention have 
excellent cling properties on the cling layer and non-cling properties, 
preferably slip properties, on the non-cling layer. Particularly, the use 
of compatible, non-migrating tackifying additives can be utilized to 
impart enhanced cling properties even in a highly stretched condition 
while not adversely effecting slip properties of the non-cling layer. The 
present thermoplastic films, as a whole, additionally have desirable 
stretch, tensile, puncture resistance and tear resistance properties. 
Further, the thermoplastic compounds used for the cling and non-cling 
layers have excellent thermal stability, and edge trim scrap can be 
processed without significant loss of film performance. This combination 
of properties makes the thermoplastic films of the present invention 
especially well suited for use as stretch/cling wraps. 
These and other features and advantages of the present invention will be 
more readily understood by those skilled in the art from reading the 
following detailed description. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides a thermoplastic film having a tackified 
cling layer wherein the cling is enhanced in both a highly stretched 
condition and an unstretched condition. That is, the cling layer of the 
film is "clingy" both before and after stretching, and can even become 
"clingier" when it is stretched. In addition, there is provided a 
thermoplastic film having excellent cling, slip, stretch, tensile, tear 
resistance, puncture resistance and thermal stability properties, making 
such film especially well suited for use as a stretch/cling wrap. 
The thermoplastic film, in its overall concept, comprises a cling layer 
which comprises a polymer of two or more monomers and a compatible 
tackifier, wherein a first monomer comprises ethylene and a second monomer 
comprises an acrylate or vinyl acetate. Acrylate, in the singular, refers 
to both a single acrylate and combinations of different acrylates. These 
polymers will generally be referred to as ethylene-acrylate (or EA) 
polymers. 
In the preferred embodiment, the EA polymer comprises an acrylate/acetate 
content of between about 20% to about 40%, more preferably above about 
24%, most preferably above about 28%, by weight based upon the weight of 
the EA polymer. The EA polymer may have a wide range of melt indexes (MI), 
generally between about 0.1 to about 30, more preferably between about 1 
to about 10 dg/min (ASTM D-1238, Condition E). 
Preferred acrylates useful in the present invention are those of the 
general formula: 
##STR1## 
wherein R is selected from hydrogen or a hydrocarbon group having from 1 
to 22 carbon atoms, preferably an alkyl, aryl, aromatic, or olefin of the 
like hydrocarbon group, and wherein R' is selected from the same or 
different of these hydrocarbon groups. 
Preferred acrylates comprise those wherein R is selected from hydrogen or 
an alkyl group and wherein R' is the same or different such alkyl group. 
Specific examples of preferred acrylates include methyl acrylate, ethyl 
acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, decyl 
acrylate, octadecyl acrylate, methyl methacrylate, ethyl methacrylate, 
n-butyl methacrylate and the like. Of these, methyl acrylate is 
particularly preferred, especially wherein the EA polymer has a methyl 
acrylate content of between about 24% to about 28% by weight of the EA 
polymer. 
As previously indicated, the EA polymer can comprise more than two monomers 
with at least a first monomer comprising ethylene and a second monomer 
comprising one or more of the above-defined acrylates. For the case of 
teror additional monomers, suitable examples include, but are not limited 
to, other free radically polymerizable monomers PG,11 such as, for 
example, acrylic acids (i.e. acrylic, methacrylic and ethacrylic acid), 
other acrylates, other vinyl esters, carbon monoxide and the like. These 
additional monomers will generally be present in small amounts, usually 
less than a total of about 10% by weight based upon the weight of the EA 
polymer. 
In a preferred embodiment, the EA polymer has a narrow molecular weight 
distribution and a reduced incidence of long chain branching which have 
been found to enhance the cling properties of the cling layer containing 
the EA polymer. The narrow molecular weight distribution of the EA polymer 
is reflected by relatively low ratios of weight average molecular weight 
to number average molecular weight (M.sub.w /M.sub.n) and z average 
molecular weight to number average molecular weight (M.sub.z /M.sub.w). 
The ratio M.sub.w /M.sub.n is preferably less than about 3.5, more 
preferably less than about 3, and especially less than about 2.5. The 
ratio M.sub.z /M.sub.w is preferably less than about 3, more preferably 
less than about 2.6, and especially less than about 2.1. A reduction in 
long chain branching is generally reflected in a low melt index swell 
ratio, i.e., the ratio of the diameter of the melt indexer extrudate (ASTM 
D-1238, Condition E) to the diameter of the melt indexer orifice. The melt 
index swell ratio is preferably less than about 1.6, and more preferably 
less than about 1.5. 
Films employing the preferred EA polymer as a cling layer have been found 
to have enhanced cling, and in particular, the cling of such films is not 
as adversely affected by stretching as similar films prepared from EA 
polymers having broader molecular weight distribution and/or more long 
chain branching. The film containing the EA polymer cling layer preferably 
has cling of the EA "inside" layer surface against the "outside" opposite 
layer surface (I/O cling) at 0% stretch of at least about 100 grams per 
inch (g), more preferably at least about 200 g, and especially at least 
about 250 g; and a 200% stretch I/O cling of at least about 90 g, and more 
preferably at least about 100 g as determined by the procedure described 
in the Examples hereinbelow. In addition, films prepared with the 
preferred EA polymer cling layer have enhanced optical properties such as, 
for example, less haze and more gloss, but retain comparable physical 
properties and processability. 
The EA polymer may be produced by any one of a number of well-known 
processes such as, for example, those described in U.S. Pat. No. 
3,350,372, which is incorporated by reference for all purposes as if fully 
set forth. Generally ethylene, acrylate and, if desired, another 
monomer(s) are metered into, for example, a high pressure autoclave 
reactor along with any one of a number of well-known free radical 
polymerization initiators (catalysts) suitable for producing EA polymers. 
Particularly preferred catalysts include organic peroxides such as, for 
example, lauroyl peroxide, di-tert butyl peroxide, tert butyl peroxide, 
tert butyl perpivilate and various azo compounds. Typically, the catalyst 
will be dissolved in a suitable organic liquid such as benzene, mineral 
oil, ISO C hydrocarbon solvent or the like. Ordinarily the catalyst is 
used at a level of between about 50 to about 20,000 ppm, more preferably 
between about 100 to about 250 ppm based upon the weight of the monomers. 
The tackifier can be added to the EA polymer during or after the 
copolymerization reaction, or otherwise mixed in any manner obtaining an 
intimate blend therewith, to improve the cling properties of the film. A 
wide variety of tackifiers are known in the art including, for example, 
polyisobutylenes, atactic polypropylenes, terpene resins, aliphatic and 
aromatic hydrocarbon resins and the like. In aforementioned application 
U.S. Ser. No. 123,002, it was noted that the EA polymers can produce films 
of sufficient cling so as to not require the use of a tackifier, and that 
the use of such tackifiers was not desirable and preferably avoided. 
However, it has been discovered that the use of a compatible tackifier in 
accordance with the present invention can enhance the cling properties of 
EA polymers in a stretched condition so that cling can be, quite 
surprisingly, even more enhanced after stretching than before stretching. 
Moreover, the use of a compatible tackifier according to the present 
invention substantially avoids the disadvantages heretofore associated 
with the tackified cling polymers of the prior art, namely migration of 
the tackifier to the cling surface or into an opposed non-cling layer and 
problems caused by such tackifier migration. 
The tackifier may be selected from a number of well known tackifiers such 
as, for example, rosin and its derivatives, and various hydrocarbon resins 
such as polyterpenes, polydienes, poly(vinyl aromatics) and the like, 
provided that the tackifier is compatible with the EA polymer, i.e. 
miscible therewith on a molecular scale under conditions of fabrication 
and use. In addition, the tackifier should be selected and used in such a 
proportion so as to obtain a cling layer of suitable characteristics. If 
an insufficient or excessive proportion of the tackifier is used, the 
cling properties of the cling layer may not be suitably enhanced. Also, if 
too much tackifier is employed, the physical properties of the cling layer 
can be adversely affected. Generally, the upper limit on the quantity of 
tackifier which can be employed depends in large part on the glass 
transition temperature of the tackifier and its compatibility with the 
cling layer EA polymer. The glass transition temperature of the cling 
layer blend should not exceed about 0.degree. C., and is preferably in the 
range of from about -20.degree. C. to about 0.degree. C. to avoid 
excessive brittleness. The proportion of tackifier used desirably should 
not exceed any upper compatibility limit, if any, or result in a glass 
transition temperature of the blend which is too high so that the cling 
layer is undesirably brittle. The tackifier preferably comprises from 
about 1% to about 20%, preferably from about 5% to about 15%, by weight of 
the cling layer. 
A preferred class of compatible tackifiers includes polar tackifiers having 
a glass transition temperature of from about -50.degree. C. to about 
50.degree. C., preferably from about -10.degree. C. to about 50.degree. C. 
Preferred polar tackifiers include rosin esters and hydrogenated rosin 
esters having an acid number from 0 to about 15 such as, for example, the 
methyl, glycerol, pentaerythritol and like esters of rosin and 
hydrogenated rosin available under the trade designations FORAL, PENTALYN, 
ZONESTER, SYLVATAC, STAYBELITE, PEXALYN and the like. These tackifiers 
typically have a Ring & Ball softening point from about 80.degree. C. to 
about 105.degree. C. FORAL 105 tackifier, a glycerol ester of hydrogenated 
rosin having an acid number of about 12 and a Ring & Ball softening point 
of about 104.degree. C., has been found to be particularly suitable. 
Another preferred class of compatible tackifiers includes amorphous 
polymerized hydrocarbon resins which are liquids or semisolids at 
25.degree. C., preferably having a softening point of from about 
10.degree. C. to about 25.degree. C. Preferred amorphous hydrocarbon 
tackifiers include polyterpenes available under the trade designations 
ZONAREX, ZONAREZ and PICCOLYTE; polymerized C.sub.5 diolefins available 
under the trade designations WINGTACK and ESCOREZ; poly(vinyl aromatics) 
available under the trade designations REGALREZ, NEVILLAC, PICCOLASTIC and 
KRISTALEX; and the like. 
Specific representative examples of hydrocarbon tackifiers compatible with 
EMA cling polymers containing 24 weight percent methyl acrylate include 
ZONAREZ A25, a polymer made by Arizona Chemical from terpene hydrocarbons 
having a softening point of about 25.degree. C.; REGALREZ 1018, a 
hydrogenated styrene-based polymer, made by Hercules, having a softening 
point of about 18.degree. C.; WINGTACK 10, a polymer made by Goodyear from 
terpenes, having a softening point of about 10.degree. C.; ESCOREZ 2520, a 
polymer made by Exxon Chemical from C.sub.5 diolefins and other reactive 
diolefins, having a softening point of about 20.degree. C.; and the like. 
The EA polymer/tackifier blend may, if desired, also include one or more 
other well-known additives such as, for example, antioxidants, ultraviolet 
absorbers, antistatic agents, release agents, pigments, colorants or the 
like; however, this should not be considered a limitation of the present 
invention. The cling layer blend should, however, be essentially free of 
incompatible additives and other ingredients in such quantities as would 
substantially impair the cling or other advantageous properties of the 
blend. 
The film of the present invention may further comprise a second cling layer 
opposite this first cling layer, but preferably further comprises a 
non-cling layer opposite the cling layer, with the non-cling layer 
preferably comprising any suitable polyolefin or combination of 
polyolefins such as polyethylene, polypropylene, copolymers of ethylene 
and propylene, and polymers obtained from ethylene and/or propylene 
copolymerized with minor amounts of other olefins, particularly C.sub.4 
-C.sub.12 olefins. Particularly preferred is polypropylene. Suitable 
polypropylene is normally solid and isotactic, i.e., greater than 90% hot 
heptane insolubles, having wide ranging melt flow rates (MFR) of from 
about 0.1 to about 300 dg/min. As is known, such polypropylene is normally 
crystalline with a density range of from about 0.89 to about 0.91 g/cc for 
isotactic polypropylene. Such polypropylene and methods for making the 
same are well-known in the art, and they are readily available 
commercially. Employing polypropylene in the non-cling layer has the added 
advantage of imparting abrasion resistance thereto. 
Also suitable is linear low density polyethylene (LLDPE), i.e., a copolymer 
of ethylene with up to about 20% by weight C.sub.3 -C.sub.10 olefin(s). 
Especially preferred olefins include 1-butene, 1-hexene, 1-octene and 
4-methylpentene-1. Suitable LLDPEs include those having a density greater 
than about 0.900 g/cc, more preferably in the range of from about 0.900 to 
about 0.940 g/cc. The LLDPEs may also have a wide ranging MI, generally up 
to about 30 dg/min, preferably between about 0.5 to about 10 dg/min. Such 
LLDPEs and methods for making the same are well-known in the art, and they 
are readily available commercially. 
Additionally, the non-cling layer may include one or more anticling (slip 
and/or antiblock) additives which may be added during or after the 
production of the polyolefin, or otherwise mixed in any manner obtaining 
an intimate blend therewith, to improve the slip properties of this layer. 
Such additives are well-known in the art and include, for example, 
silicas, silicates, diatomaceous earths, talcs and various lubricants. 
These additives are preferably utilized in amounts ranging from about 100 
ppm to about 20,000 ppm, more preferably between about 500 ppm to about 
10,000 ppm by weight based upon the weight of the non-cling layer. 
The non-cling layer may, if desired, also include one or more other 
well-known additives such as, for example, antioxidants, ultraviolet 
absorbers, antistatic agents, release agents, pigments, colorants or the 
like; however, this again should not be considered as a limitation of the 
present invention. 
Additionally, normal trim and scrap from the film production process can be 
recycled into either the cling or non-cling layers, but preferentially to 
the non-cling layer of a two-layer film or the core structural layer of a 
three-layer film. 
The present invention may also include one or more intermediate layers 
between the cling and non-cling layers for any one of a number of 
well-known purposes such as, for example, to modify the overall physical 
properties balance of the film, to utilize the recycle trim and scrap or 
to provide a barrier layer to oxygen or other gases. As just indicated, 
this intermediate layer may include the recycle trim and scrap, or may 
comprise any other suitable polymer. The intermediate layer(s), however, 
is optional and should not be considered a limitation on the present 
invention. 
In preparing the thermoplastic stretch/cling films of the present 
invention, any one of a number of well-known extrusion or coextrusion (in 
the case of multilayer films) techniques as disclosed in the previously 
incorporated references may be utilized. As preferred examples, any of the 
blown or chill roll cast processes as disclosed and described in those 
references is suitable for use in producing thermoplastic stretch/cling 
films in accordance with the present invention. 
In a multilayer film, the cling layer preferably comprises between about 5% 
to about 95%, more preferably between about 5% to about 35%, most 
preferably between about 5% to about 15% of the combined thickness of the 
film layers. Conversely, the non-cling layer(s) (including any structural 
or other intermediate layer) preferably comprises between about 5% to 
about 95%, more preferably between about 65% to about 95%, most preferably 
between about 85% to about 95% of the combined thickness of the film 
layers. 
As previously mentioned, the thermoplastic films of the present invention 
have properties making them especially well suited for use as 
stretch/cling films, however this use should not be considered a 
limitation on the present invention. For example, these films can be made 
into other forms, such as a tape, by any one of a number of well-known 
cutting, slitting and/or rewinding operations. Physical properties 
including, but not limited to, tensile strength, tear strength and 
elongation can be adjusted over wide ranges by altering the resin types 
and specifications as appropriate to meet the requirements to a given 
wrapping, bundling or taping application. 
For bundling, packaging and unitizing applications, the thermoplastic film 
of the present invention is stretchwrapped by any one of a number of 
well-known procedures (such as those disclosed in the aforementioned 
incorporated references) around an article or a plurality of articles 
preferably so that the cling layer faces inside (towards the article) and 
the non-cling layer faces outside (away from the article), although this 
film orientation should not be considered as a limitation on the 
invention. Typical of articles suitable for bundling, packaging and 
unitizing with the present thermoplastic film include, but are not limited 
to, various foodstuffs (canned or fresh), rolls of carpet, liquid 
containers and various like goods normally containerized and/or palletized 
for shipping, storage and/or display. 
The foregoing more general discussion of this invention will be further 
exemplified by the following specific examples offered by way of 
illustration and not limitation of the above-described invention.

EXAMPLES 
In the following examples, property evaluations were made in accordance 
with the following tests: 
(1) Coefficient of Friction (COF)--ASTM D-1894. 
(2) Cling--cling is reported as the force in grams required to partially 
peel apart two strips of film. A first film strip is attached to a 
30.degree. inclined plane with the outside surface (slip) facing upward. A 
second 1" X 8" strip is placed on top of the first strip with the inside 
surface (cling) facing downward. Pressure is applied to the second strip 
to cause the two strips to stick together. If an evaluation of cling under 
stretched conditions is desired, both film strips are prestretched and 
allowed to relax before testing. The end of the second strip at the base 
of the inclined plane is attached, by clip and string, to an apparatus 
which can exert a strain at a constant rate (Instron 1130). The two strips 
are then pulled apart at a crosshead speed of 10 cm/min until the 
aforementioned string is parallel with the base of the inclined plane. The 
force at this point is reported as cling. 
EXAMPLES 1-4 
An ethylene-methyl acrylate (EMA) copolymer, having a methyl acrylate 
content of 24 weight percent and a MI of 5 dg/min, was blended with FORAL 
105 tackifier in a proportion ranging from 0 to 15 weight percent. The 
EMA/FORAL blends were coextruded with a polypropylene (PP) having a melt 
flow rate (MFR) of about 12 dg/min (commercially available from Exxon 
Chemical Company, Houston, Tex., under the trade designation PP-3014). 
Slip (Kememide E, a commercial erucamide available from Humko Chemical 
Company, Memphis, Tenn.) and antiblock (AB) (Super Floss.TM. a commercial 
silica available from Johns Manville) were added to the PP. Other 
properties of the EMA, FORAL 105, EMA/FORAL blends and PP are listed below 
in Table I. 
The EMA copolymer and FORAL 105 tackifier were blended on a Banbury mixer 
and pelletized on a Davis Standard Thermatics at a melt temperature of 
about 350.degree. F. under a nitrogen blanket. The film was produced by 
coextruding the EMA copolymer/FORAL 105 tackifier blend and PP-3014 on a 
Killion cast film line with two 3/4" extruders, respectively, for the EMA 
blend and PP layers. The EMA blend was extruded at a melt temperature of 
about 410.degree. F., while the PP was extruded at a melt temperature of 
about 480.degree. F. The chill roll temperature was set to 80.degree. F. 
and the line speed averaged about 30 feet per minute. 
The resulting film had a gauge of 1 mil with the EMA blend layer comprising 
about 20% of the total film thickness. The O/O slip (the PP layer surface 
against the PP layer surface) was then measured as the coefficient of 
friction (COF) for 0%, 100% and 200% stretch, and I/O cling (EMA/PP) 
results are presented below in Table I. 
TABLE I 
______________________________________ 
CLING LAYER 
COMPOSITION 
(wt. %) CLING (g).sup.1 
FORAL 0% 100% 200% 
EXAMPLE EMA 105 Stretch 
Stretch 
Stretch 
______________________________________ 
1 100 0 150 80 60 
2 95 5 250 150 170 
3 90 10 288 246 268 
4 85 15 595 n/a 688 
______________________________________ 
.sup.1 EMA to PP layer surfaces 
n/a = data not available 
The foregoing results show that films in accordance with the present 
invention exhibited enhanced cling properties upon stretching, and 
otherwise had good physical properties, extrusion processability and 
utility appropriate for stretch/cling wrap applications. The results 
further suggest the ability to tailor film cling and slip properties and 
balance properties by altering variables including the EA polymer 
comonomer content, tackifier content, resin type(s) of the non-cling 
layer, slip additive content of the non-cling layer and antiblock additive 
content of the non-cling layer. 
The films of the invention may also be used in surface protection 
applications. Especially at high acrylate content, viz, above about 24% 
methyl acrylate in the EA polymer, the films are very effective in the 
temporary protection of surface during manufacturing, transportation, etc. 
The easily coextruded films of the invention are also often less expensive 
than known surface protection films of, e.g., LLDPE and acrylic layers. 
Advantageously, the films of the invention do not leave significant 
adhesive traces on the surface to be protected and have good UV stability. 
Many modifications and variations besides the embodiments specifically 
mentioned may be made in the compositions and methods described herein 
without substantially departing from the concept of the present invention. 
Accordingly, it should be clearly understood that the form of the 
invention described herein is exemplary only, and is not intended as a 
limitation of the scope thereof.