In-line method for laminating silicone-coated polyester film to paper, and laminate produced thereby

A multi-layered sheet product is provided which is useful as a release backing for pressure sensitive adhesive labels or as a liner for foodstuff containers and trays. The sheet product has a polymeric layer and a cellulosic layer laminated together and having an adhesive layer therebetween. A substantially uniform silicone coating is provided on a surface of the polymeric layer opposite the surface adhered to the cellulosic layer. The polymeric layer surface having the silicone coating thereon constitutes a smooth surface which, when the product is used as a release backing, minimizes distortion of the adhesive surface of an adhesive label upon separation of the label from the sheet product, an important feature for use with transparent labels. When used as a release liner for foodstuff containers and trays, the polymeric layer prevents absorption by the cellulosic layer of water from the foodstuff. Use of an oriented polyester as the polymeric layer, provides excellent tear resistance, dimensional stability and stiffness in an extremely thin laminated sheet product.

FIELD OF THE INVENTION 
The present invention relates to a method of making multi-layered sheet 
products which are useful as release backings for pressure sensitive 
adhesive labels, and as liners for containers and trays used in the food 
and industrial compound industries. The present invention also relates to 
multi-layered sheet products produced by such methods. 
BACKGROUND OF THE INVENTION 
Pressure sensitive adhesive labels are generally provided with a releasable 
backing known as a backing layer, release layer or release liner. The 
backing protects the adhesive surface of the label from contamination by 
dust, debris, moisture and other contaminants until the label is ready for 
use. It is important that the backing is easily releasable from the label 
so that the label does not tear when separated from the backing. Easy 
release is also needed so that the adhesive layer of the label remains 
intact during separation, enabling maximum adhesion of the label when 
applied to a subsequent surface. 
Silicone coatings on paper products are well known as suitable materials 
for release liners, release backings and other low surface energy 
surfaces. Unfortunately, such materials are not suitable as moisture and 
water barrier materials, and are relatively expensive due to the thickness 
required for such materials to be commercially durable. Furthermore, 
silicone-coated paper products have a rough topography due to the fibrous 
and porous nature of the paper. The topography of the paper tends to be 
transferred to and adversely affects the smoothness of the label adhered 
to it. This is particularly troublesome when paper release backings are 
used for transparent labels having adhesive layers which tend to pick up 
the topography of the backing. When the rough topography of the backing is 
transferred to the adhesive layer of a transparent label, clarity of the 
adhesive layer and thus the label is diminished. A need therefor exists 
for an extremely smooth backing material which will not cause the transfer 
of a rough topography to the adhesive layer of a transparent label. 
Other problems with the use of silicone-coated paper backing and liner 
materials is the tendency of such materials to rip or tear during a 
diecutting operation. A need exists for a backing and liner material which 
can be neatly cut by a diecutting press so as to achieve a finished form 
having smooth edges. 
Release-coated surfaces are also desirable for containers, trays and 
support sheets which contact foodstuffs, and for drums, tubes and 
containers for tacky or sticky industrial compounds. Complete release of 
foodstuffs and industrial compounds from such surfaces is essential to 
minimizing waste of such products. Complete release of foodstuffs from 
container surfaces also preserves the appearance of the foodstuff and thus 
provides an aesthetically pleasing presentation of the product. For 
example, it would be desirable to provide a release-coated surface on a 
pizza box or pizza tray insert so that melted cheese overflowing from a 
slice of pizza will not stick to the box or tray. When melted cheese from 
a slice of pizza flows onto the surface of existing cardboard pizza boxes, 
the cheese sticks to the box and pulls more toppings off the slice as it 
is lifted from the box. A need therefore exists for food containers, 
support sheets and trays provided with release coatings which prevent 
sticking of foodstuffs to the surfaces thereof. 
Likewise, a need exists for an industrial composition or compound container 
such as a drum or tube having a release coating thereon which prevents 
sticky or tacky industrial compounds from sticking to the container. 
Coated paper liners are also known for food containers and industrial 
compound containers, and are desirable in that they offer good 
printability and stiffness. Unfortunately, coated paper liners require 
sufficient thickness to provide satisfactory tear resistance and they 
suffer from the undesirable properties of moisture scavenging and curling. 
Moisture scavenging results in the absorption of water content from 
foodstuffs and industrial compounds in contact with the liner, thereby 
adversely affecting the quality of the contained foodstuff or industrial 
compound and the structural stability of the container. 
Certain polymeric compositions provide good moisture barrier properties and 
tear resistance, but offer poor printability and stiffness. Polymeric 
liners may also be dimensionally unstable for many applications. U.S. Pat. 
No. 5,244,702 discloses a paper-plastic laminate sheeting which can be 
used for manufacturing grocery bags and envelopes. The patent does not 
suggest, however, that the laminate could be used as a release backing. 
The plastic layer may comprise a film of polypropylene, polyethylene, 
nylon or polyester. To avoid diminishing the reinforcing characteristics 
of the film, the patent teaches using a water-based adhesive, and not a 
hot melt adhesive, for laminating the film to a paper layer. To render the 
inner surface of the film more receptive to the water-based adhesive, the 
patent teaches first subjecting the film surface to an ionizing treatment 
to increase the surface energy of the film surface. 
It has been found that ionization treatments, unless conducted at extremely 
low power, can deleteriously affect and even destroy silicone coatings on 
a thin polymeric film. Destruction of silicone coatings on thin polymeric 
films may occur even when the opposite surface of the film is the only 
surface exposed to the ionization treatment. 
The present invention provides a backing and liner material having a 
silicone release surface. The multi-layered products of the present 
invention exhibit excellent release, printability, stiffness, tear 
resistance, and dimensional stability together with moisture barrier 
properties. The present invention provides a method of producing such 
backing and liner materials in a thin structure and at a continuous high 
production rate without deleteriously affecting the silicone release 
surface. The printability and stiffness of a coated paper release 
structure and the tear resistance and moisture barrier properties of a 
polymeric liner are achieved while avoiding curling problems and swelling 
due to absorption of water into a paper layer. 
The highly smooth silicone-coated polymeric surface eliminates problematic 
transfer of a rough topography to label adhesives. The present backing and 
liner materials may be substantially thinner, e.g., thinner than about 60% 
as thick, yet at least as strong as silicone-coated paper materials. In 
addition, the materials of the present invention possess a smooth surface 
for diecutting which leads to precise cutting of forms with a minimal risk 
of material ripping or tearing. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a backing and liner material is 
provided which comprises a polymeric material layer having a substantially 
uniform silicone coating formed on one side thereof, an adhesive layer, 
and a cellulosic material layer, wherein the adhesive layer is disposed 
between the polymeric material layer and the cellulosic material layer to 
adhere them together. The resultant structure can be extremely thin, e.g., 
thinner than about 60% the thickness of comparable silicone-coated paper 
release materials, yet offer excellent release properties and durability. 
The preferred polymeric material for the polymeric layer is an oriented 
polyester material, particularly oriented polyethylene terephthalate. The 
surface of the polymeric layer having the silicone coating thereon is 
extremely smooth and provides a release surface of very low surface 
energy. As a result of its highly smooth surface, the structure of the 
invention is ideal for a transparent adhesive label backing because the 
smooth surface minimizes distortion of the pressure sensitive adhesive 
layer on the label when the label is separated from the backing. As a 
result, there is no transfer of rough topography from the backing to the 
label adhesive layer because the topography of the backing material is 
extremely smooth. The low degree of distortion enables the adhesive layer 
of the label to have excellent clarity, a particularly advantageous 
feature for transparent labels. 
The multi-layered structure of the present materials combines all the 
advantages of coated paper backings and polymeric liners, and provides 
such advantages in a thin structure which can be thinner than about 60% 
the thickness of silicone-coated paper backing materials. The structures 
of the invention exhibit excellent release, printability, stiffness, tear 
resistance, and dimensional stability together with moisture barrier 
properties. 
In addition, the methods of the present invention enable fast production 
rates on a continuous, in-line basis. The silicone-coated polymeric 
material layer is continuously adhered to the paper layer without 
substantially disrupting or destroying the silicone coating or 
deleteriously curling or swelling the paper layer. In preferred 
embodiments, a hot melt adhesive is continuously applied to the polymeric 
material to provide an adhesive layer, and then the paper layer is 
laminated to the polymer layer in the nip of counterrotating rollers. At 
least one of the rollers is preferably a chilling roll which solidifies 
the adhesive and keeps the paper and the silicone-coated polymeric layer 
sufficiently cool so as to avoid substantial distortion or destruction 
thereof. In embodiments of the invention, the polymeric material is 
subjected to low levels of corona discharge to facilitate bonding of the 
adhesive to the polymer without substantially adversely affecting the 
release properties of the silicone coating. 
In preferred embodiments of the invention, a multi-layered structure is 
provided comprising an oriented polyethylene terephthalate polymeric layer 
having an outer surface coated with a polymerized silicone composition and 
adhered to a paper layer by a polyolefinic hot melt adhesive. Some 
preferred structures according to the invention may have a polymeric layer 
thickness ranging from about 0.25 to about 1.5 mils, laminated to a paper 
layer comprising tissue paper or kraft paper having a thickness of up to 
about 12 point paper stock, depending upon the desired application of the 
product. Thicker polymeric and cellulosic layers are also within the realm 
of the present invention. 
The present invention provides an adhesive label in combination with a 
releasable backing, and more particularly provides transparent pressure 
sensitive adhesive labels. In addition, the present invention provides 
containers, trays and supports with release liners therefor which come in 
contact with foodstuffs or tacky industrial compositions such as resins.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides multi-layered sheet and web materials 
comprising a silicone-coated polymeric layer adhesively laminated to a 
cellulosic layer. In addition, the invention provides a method of 
manufacturing such materials at high speed using conventional laminating 
equipment. The materials of the invention may be used as a release backing 
for adhesive labels or as a liner for containers, trays and support 
surfaces for foodstuffs and industrial compositions or compounds. The 
materials are particularly well suited for use as release backings for 
transparent pressure sensitive adhesive labels and as liners for 
containers or surfaces which contact sticky or tacky foodstuffs or 
industrial compositions or compounds. In embodiments of the invention, the 
thickness of silicone-coated paper products may be reduced by at least 
about 40% without loss of strength by laminating a thinner layer of paper 
to a silicone-coated thin polymer layer. For example, a 2.5 mil thick 
silicone paper backing may be replaced by a laminated structure according 
to the invention having a thickness of about 1.5 mils or less. 
The structure of the present invention provides a release backing for an 
adhesive label wherein the silicone-coated surface of the polymeric layer 
is sufficiently smooth to minimize surface distortion of the label 
adhesive as the label is separated from the silicone coating. The need for 
such a smooth surface is particularly important when the label is 
substantially transparent. If the silicone-coated surface of the polymeric 
layer is not smooth, the adhesive layer of the label tends to become 
surface distorted when the label is peeled from the release backing, 
adversely affecting the clarity of the adhesive label. Distortion of the 
label adhesive is especially disadvantageous when the label is 
substantially or fully transparent. Furthermore, the adhesive layer of the 
label tends to map or pick-up the surface contour or topography of the 
backing, which can also adversely affect clarity of a transparent label 
and the smoothness of the label when the silicone-coated release surface 
of the backing is not sufficiently smooth. 
The multi-layered sheet materials of the present invention may be produced 
by: (a) providing a polymeric material layer having a first surface and an 
opposite second surface, (b) forming a substantially uniform and smooth 
silicone coating on the first surface, (c) providing a cellulosic material 
layer adjacent the polymeric material layer, (d) providing an adhesive 
layer between the second surface and the cellulosic material layer, and 
(e) causing the second surface and the cellulosic material layer to 
contact and adhere to one another via the adhesive layer therebetween to 
form a multi-layered product. In embodiments of the invention, the 
silicone coating may be applied and then the silicone-coated polymer may 
be laminated to the paper all in-line, without rolling up the polymeric 
layer. In other embodiments, prefabricated silicone-coated films may be 
employed. The prefabricated silicone-coated polymeric film may be supplied 
in rolled-up form and then unrolled prior to lamination to the cellulosic 
layer. 
The polymeric layer of the present invention can be manufactured from 
various polyester resins. Polyethylene terephthalate, polytetramethylene 
terephthalate, polyethylene 2,6-naphthalate, and 
polyethylene-1,4-cyclohexylene dimethylene terephthalate are examples of 
homopolymers which may be employed in the practice of the present 
invention. Polyester copolymers may also be used. Possible copolyesters 
include polyethylene terephthalate/isophthalate, polyethylene 
terephthalate/adipate, polyethylene terephthalate/sebacate, and 
polyethylene terephthalate/sulphoisophthalate. Polyethylene terephthalate 
homopolyester is preferred. 
Polyester films are preferred for the polymeric material layers of the 
invention because of their smoothness, strength, tear resistance and 
moisture barrier characteristics. According to a preferred embodiment of 
the invention, polyethylene terephthalate (PET) is a preferred film 
material, particular oriented PET which has been stretched uniaxially or 
biaxially. 
If polyester is used as the polymeric layer, the polyester film may also 
include other polymers but preferably the film has a polyester content 
greater than about 85% by weight. For example, a blend of polyester and 
polyolefin, such as polyethylene terephthalate/polyethylene, or a blend of 
polyester and polyamide, such as polyethylene terephthalate and nylon may 
be employed. 
The silicone coating on the polymeric layer provides a low surface energy 
surface which enables the laminated materials of the invention to be 
well-suited for release backing and release liner applications. While many 
methods are provided for forming a low surface energy silicone coating on 
a polymeric layer, preferred methods for preparing silicone-coated 
polyesters are described in commonly assigned U.S. patent application Ser. 
No. 07/773,323, filed Oct. 11, 1991, now abandoned, U.S. application Ser. 
No. 08/476,001, filed Jun. 7, 1995, and U.S. application Ser. No. 
08/601,587, filed Feb. 14, 1996, now U.S. Pat. No. 5,728,339, and European 
Patent no. 536,766, granted Sep. 11, 1996, all in the name of Grover L. 
Farrar for "In-Line Silicone-coated Polyester Film And A Process For 
Coating The Film," the entireties of which are herein incorporated by 
reference. 
As a preferred polymer, the manufacture of a silicone-coated oriented 
polyester film for the polymeric layer will be described. It is to be 
understood that similar processes can be used to make coated polymeric 
layers comprising different polymers. 
The polyester film of the present invention can be manufactured by an 
extrusion process. Polyester resin is first heated to a molten state and 
then extruded through a wide slot die in the form of an amorphous sheet. 
The sheet-like extrudate is rapidly cooled or quenched to form a cast 
sheet of polyester by extruding the amorphous sheet around a polished, 
revolving chilled casting drum. The cast polyester sheet can then be 
stretched in one or more directions, while being heated to a temperature 
in the range of from about 80.degree. C. to about 160.degree. C., 
preferably from about 90.degree. C. to about 100.degree. C. The degree of 
stretching may range from about three to five times the original cast 
sheet unit dimension. Preferably, the polyester film is biaxially oriented 
(stretched in both the machine direction and the transverse direction) 
rather than uniaxially oriented. 
Prior to coating the polyester film surface with the silicone coating, the 
film may be surface-treated in a conventional manner by exposure to an 
electric corona discharge. Electric corona discharge is a conventional 
surface treatment which is commonly performed on polyester films to 
enhance the film's wetting property. Electric corona discharge methods and 
apparatus are described in U.S. Pat. Nos. 3,057,792 and 4,239,973. In 
embodiments of the invention, power levels which may be used prior to 
coating the polyester film with silicone may range up to about 5 watts per 
square foot per minute, for example from about 1.5 to about 4 watts per 
square foot per minute. 
For uniaxially oriented film, the corona treatment followed by the silicone 
coating application may occur during the in-line manufacturing process, 
either before stretch orientation or after stretch orientation. If the 
corona treatment followed by the coating occurs before stretch 
orientation, heating the film before stretch orientation will usually 
drive off the water in the coating. If the corona treatment and coating 
for a uniaxially oriented film occurs after a machine direction stretch 
during an in-line manufacturing process, the film should be completely 
dried before winding the film. Heat-setting the film to lock-in the 
physical properties is generally sufficient to dry the film before 
winding. For uniaxially oriented film, the preferred procedure is to 
corona treat and coat the film before stretch orientation. 
For biaxially oriented film, the corona treatment followed by the coating 
may occur during the in-line manufacturing process either before stretch 
orientation, between the machine draw and the transverse draw, or after 
biaxial orientation. Again, if the corona treatment and coating step occur 
after stretch orientation is complete, it is preferred that the film be 
completely dry before winding. Moreover, the biaxially oriented film 
should be heat-set to lock-in the physical properties of the film, and 
heat-setting is generally sufficient to dry the film before winding. If 
the corona treatment or coating occurs before orientation, or between 
draws during orientation, the latter orientation steps are generally 
sufficient to drive off the water from the coating. Preferably, for 
biaxially oriented film, the corona treatment and subsequent coating occur 
between draws during the stretch orientation stage. 
The polymeric layer, preferably a polyester sheet, is coated on the 
electric corona discharge treated surface with a silicone coating. The 
coating composition may conveniently be applied as an aqueous emulsion 
using any of the well known coating techniques. For example, the film may 
be coated by roller coating, spray coating, gravure coating, reverse 
gravure coating, or slot coating. The heat applied to the film during the 
subsequent preheating, stretching and heat-setting stages is generally 
sufficient to evaporate the water and cure and bind the coating to the 
polyester film. 
The oriented polyester film, whether uniaxially oriented or biaxially 
oriented, is generally heat-set at a temperature ranging from about 
190.degree. C. to about 240.degree. C., preferably from about 215.degree. 
C. to about 235.degree. C. The coated oriented polyester film is then 
wound into a roll for further processing or shipping. 
The silicone coating is generally prepared by hydrolyzing a glycidoxy 
silane in deionized water and blending with an aqueous silicone resin 
emulsion and its corresponding crosslinker. Generally, the aqueous 
silicone resin compositions are platinum catalyzed. However, condensation 
type siloxanes may be employed and the emulsion may be catalyzed with a 
tin catalyst. The crosslinker employed should be that recommended by the 
particular silicone resin composition manufacturer for that specific 
aqueous silicone resin composition. 
Examples of aqueous based silicone resin compositions which may be employed 
are: 
1) Dow Corning (Midland, Mich.) Syl-off X2-7720, or 7900, or 7910, aqueous 
silicone resin composition comprising methyl vinyl polysiloxane and methyl 
hydrogen polysiloxane with either the X2-7721 or 7922 crosslinking system 
comprising platinum polysiloxane; 
2) G. E. Silicones (Schenectady, N.Y.) SM3200 aqueous silicon resin 
composition comprising methyl vinyl polysiloxane and methyl hydrogen 
polysiloxane with the 3010 crosslinking system comprising platinum 
polysiloxane. 
3) Wacker Silicone (Adrian, Mich.) aqueous based 410E silicone resin 
composition comprising methyl vinyl polysiloxane and platinum with the V20 
crosslinking system comprising methyl hydrogen polysiloxane; 
4) PCL (Rhone-Poulenc Inc., Rock Hill, S.C.) PC-105 aqueous based silicone 
resin composition comprising methyl vinyl polysiloxane and methyl hydrogen 
polysiloxane with the catalyst component of PC-95 comprising platinum 
polysiloxane; 
5) PCL PC-107 (Rhone-Poulenc Inc.) aqueous based silicone resin composition 
(similar to PC 105) with the above-identified PC-95 crosslinker; and 
6) PCL PC-188 (Rhone-Poulenc Inc.) aqueous based silicone resin composition 
(similar to PC 105) with the above-identified PC-95 crosslinker. 
The amount of deionized water blended with the aqueous silicone resin 
composition is dependent upon the coating method and desired amount of 
solids, by weight, to be coated on the polyester film. 
The glycidoxy silane may be a glycidoxypropyltrimethoxysilane or generally 
any glycidoxysilane represented by the formula X--Y--Si--R1, R2, R3, 
wherein X is a glycidoxy group, Y is an alkylene group, such as methylene, 
ethylene, propylene, etc., and R1, R2, and R3 are hydrolyzable groups, 
such as methoxy, ethoxy, acetoxy, and the like. These silanes possess 
water solubility or water dispersibility. 
The solids level of the coating may be from about 3% to about 30% by weight 
solids. Preferably, the percent solids, by weight, is from about 5% to 
about 15%. While it may be possible that a solids concentration below 3% 
by weight for the coating may be effective, it is believed that such a 
level would be minimally effective. Additionally, while a solids level 
greater than 30% by weight may be effective, it is believed that at such a 
level, a haze may result in the film, or the coating is more expensive but 
no more effective than a film having a solids level in the preferred 
range, for example. 
As previously mentioned, the coating comprises the aqueous thermosetting 
silicone resin composition, including any necessary crosslinkers, etc., 
and the glycidoxy silane. The minimum amount of glycidoxy silane believed 
to be effective for an aqueous silicone resin composition in the present 
invention is about 1.0% by weight of the silicone solids. At the preferred 
coating solids level of about 5% to about 15% by weight, the glycidoxy 
silane concentration in solution is from about 0.5% to about 1.5%, by 
weight. On a dry weight basis, the glycidoxy silane is preferably from 
about 3% to about 30% of the silicone solids. Using much more than about 
30% by weight of the glycidoxy silane on a dry weight basis is expensive 
and may not yield proportionally better results. 
The coating weight of the coating may be from about 0.02 lb./ream to about 
0.10 lb./ream. Coating thicknesses of from about 750 angstroms to about 
1500 angstroms are preferred. Generally, a thickness less than the above 
amount is not effective as a release coating, while a thickness more than 
the above amount is not cost effective. 
The thickness of the polymeric layer depends upon the desired application 
of the finished multi-layered product. When used as a release backing for 
an adhesive label, it is preferred that the polymeric layer, which 
includes the silicone coating, has a thickness of from about 0.25 mil to 
about 1.5 mils, with thicknesses in the range of from about 0.5 mil to 
about 1.0 mils being more preferred for some applications. When used as a 
liner for containers and surfaces which contact foodstuffs or industrial 
compounds, slightly thicker polymeric layer thicknesses may be preferred, 
depending upon many factors including the thickness of the cellulosic 
layer, the desired flexibility of the product, and the weight and form of 
the foodstuff or compound which will contact the liner. For example, a 
liner for a 55 gallon drum of granular-containing industrial resin would 
generally require a thicker polymeric layer thickness than a liner for a 
one pint box of light syrup. 
The surface of the polymeric layer opposite the silicone-coated surface, 
herein referred to as the bottom surface, is adhered to the cellulosic 
material layer by a laminating adhesive. To increase the adhesion of the 
polymeric layer to the adhesive, and thus to the cellulosic layer, the 
laminating surface of the polymeric layer may be surface treated when 
certain laminating adhesives are used. Chemical treatments, flame 
treatments, corona discharge treatments, and combinations of such 
treatments may be used to prepare the laminating surface. However, the 
surface treatments should not deleteriously affect the silicone coating on 
the opposite surface of the polymeric layer. 
For example, corona treatment may be appropriate to improve wet-out of a 
water-based adhesive on the polymeric layer laminating surface. A 
preferred surface treatment is a corona discharge treatment of the 
laminating surface at a power and rate which are sufficiently low so as to 
avoid substantial adverse affects upon the releaseability of the silicone 
coating on the opposite side of the polymer layer. Exemplary low power 
corona discharge treatments which may be employed are treatments of less 
than 0.5 watt per square foot per minute, preferably about 0.2 watt per 
square foot per minute, or less, and most preferably about 0.1 watt per 
square foot, or less. Even at such low power, such as 0.1 watt per square 
foot, corona treatment provides a treated surface with improved wet-out 
and bondability characteristics which are particularly important when a 
water-based adhesive is used for laminating. Higher power surface 
treatments are generally avoided as they may undesirably affect the 
smoothness and release characteristics of the opposite silicone-coated 
surface, even if applied only to the film surface opposite the 
silicone-coated surface. It has been found that corona treatments of the 
bottom surface of a 142 gauge silicone-coated PET film with as little 
power as 0.5 watt per square foot per minute may substantially destroy the 
silicone coating on the opposite surface of the film. Thicker polymeric 
layer thicknesses offer more protection to the silicone coating and can 
thus be treated with higher power corona treatments. Preferably, if a 
corona treatment of the polymeric layer is employed, the treatment is of a 
power and rate which improves wet-out characteristics of the laminating 
film surface without substantially adversely affecting the opposite 
silicone-coated surface of the layer. 
When hot melt resin adhesives are employed, it has been found that no 
corona treatment of the film surface is necessary as adhesive wet-out and 
bondability to the polymeric layer is generally excellent even without 
corona treatment. 
When the polymeric layer is provided as a web or film of already 
silicone-coated polymeric material, and the laminating surface is to be 
corona treated, it is preferred to corona discharge treat the laminating 
surface of the layer after it is unrolled from the web. If surface treated 
prior to being rolled up, the treated laminating surface may stick to the 
silicone-coated top surface it is rolled onto and thus cause an undesired 
transfer of the silicone coating to the bottom surface. 
The cellulosic material layer preferably comprises a paper material. In 
embodiments of the invention, the cellulosic material may be a tissue 
paper layer, a kraft paper layer, a paper board stock including paper 
boards of up to and exceeding 12 point board stock, fiberboard drum 
sidewall material layers, and rayon material layers. In addition, the 
cellulosic material may comprise a cardboard material, corrugated 
cardboard, or other sheet-like pulpous or fibrous materials, including 
cotton-containing sheets and the like. Herein the term "cellulosic 
material" includes cotton-containing sheet-like structures, and the terms 
"sheet" and "sheet-like" describe both rectangular single pieces of 
cellulosic material and webs of such materials. Preferably, the surface of 
the cellulosic material layer is left untreated, or treated to increase 
adhesion of the layer to the laminating adhesive. 
The laminating adhesive preferably comprises at least one adhesive selected 
from hot melt adhesives such as extruded polyolefins, solvent adhesives, 
emulsion adhesives, and wet lamination adhesives. The adhesive composition 
is primarily chosen to be compatible with the plastic film, as the paper 
layer is generally amenable to adhesion by various types of adhesive 
compositions. According to a preferred method and structure of the 
invention, the laminating adhesive is an extruded hot-melt polyolefin, 
more preferably an extruded low density polyethylene (LDPE). According to 
one preferred embodiment of the invention, a low density polyethylene is 
melted at a temperature of between about 585.degree. and about 610.degree. 
F. and extruded to laminate a silicone-coated PET layer to kraft paper. 
The amount of laminating adhesive used should be just sufficient to weld 
the polymeric and cellulosic layers together, without significantly 
increasing the thickness of the overall structure. Laydown amounts of LDPE 
laminating adhesive in the range of from about 7 to about 14 pounds per 
3000 square foot ream are preferred. The hot melt adhesive is preferably 
extruded between the polymeric and cellulosic layers adjacent a 
compression nip which laminates the layers together. When wet lamination 
adhesives are used, particularly water-based adhesives, it is preferable 
to laydown the adhesive immediately adjacent a compression nip or first on 
the polymeric layer. Otherwise, liquid or water from such adhesives may 
undesirably absorb into the cellulosic layer. Generally, the adhesive is 
applied to provide a continuous layer of adhesive so as to avoid adverse 
affects upon the topography of labels. However, in other embodiments of 
the invention, the adhesive may be applied intermittently or spotwise 
between the polymer layer and cellulosic layer. For example, in the 
production of trays or pizza boxes, a continuous adhesive layer may not be 
required. 
The adhesive may be applied to the film well before the film reaches the 
compression nip, but applying the adhesive at a substantial distance from 
the compression nip is avoided when a hot melt is used to prevent 
premature cooling of the adhesive prior to lamination. Water-based and 
solvent-based adhesives are preferably applied to the polymeric film and 
not to the paper layer, to minimize absorption of water or solvent into 
the paper layer and thus to minimize curling and swelling of the laminated 
product. If a water-based or solvent-based adhesive is used, it can 
applied to the film a substantial distance from the compression nip so 
long as the adhesive adequately wets out on the film and the wet-out 
characteristics are not deleteriously affected during the time it takes 
for the adhesive-coated film to reach the laminating compression nip. 
Preferably, the adhesive is applied just prior to the film entering the 
nip. In a preferred embodiment, the adhesive is applied to the film as the 
film passes around a compression roller which forms the laminating 
compression nip. While the application of a continuous layer of hot melt 
adhesive is preferred, e.g., a polyethylene hot melt, the adhesive may 
also be applied in a continuous or discontinuous layer by spraying, 
brushcoating, or rolling. An offset gravure system can be used to apply a 
uniform pattern of adhesive dots to the film. Alternatively, the adhesive 
may be applied to the paper prior to the paper entering the laminating 
compression nip. 
Drying conditions for the laminating adhesive should be selected to 
minimize curling of the finished product. Exemplary drying temperatures 
may range from about 225.degree. F. to about 300.degree. F. for drying a 
water-based adhesive. When a water-based or a solvent-based adhesive is 
used, the adhesive is preferably applied immediately before laminating, 
and drying occurs immediately after laminating. When hot-melt adhesives 
are used for laminating, the adhesives are preferably chilled immediately 
after lamination to minimize or prevent heat distortion of the polymeric 
layer and silicone coating due to the high temperature of the hot-melt 
adhesive. 
According to a preferred embodiment of the invention, one of the two 
laminating rollers is chilled to prevent excessive softening of the 
plastic film or disruption or distortion of the silicone coating. A 
chilled roller is particularly preferred when the hot melt adhesive is 
applied at a temperature which approaches or exceeds the softening 
temperature, or glass transition temperature (Tg), of the film material. 
The melting point of the hot melt adhesive is preferably below the glass 
transition temperature of the polymeric layer so as to avoid substantial 
distortion or softening of the polymeric layer. Chilling roll temperatures 
may range, for example, from about 50.degree. F. to about 85.degree. F. 
A preferred adhesive for use with a polyethylene terephthalate film is a 
molten composition consisting essentially of low density polyethylene. 
Pigments and other additives may be added to the adhesive composition if 
desired, but hot melt adhesives have been found to yield a high strength 
bond without the use of water or a solvent. The absence of water or 
solvent when a hot melt adhesive is employed, results in little or no 
absorption of the adhesive or adhesive carrier into the paper layer and no 
swelling or curling problems with the resultant product. A molten resin 
adhesive can be extruded across the width of the film and/or paper as they 
enter, or preferably just prior to entering, the compression nip between 
the laminating rollers. 
In practice, the laminating system may be driven by a motor to operate at a 
speed of between about 150 and about 500 feet per minute, or even at a 
greater rate. The operating speed is limited by the strength of the paper 
web. For a relatively thin paper of low strength, the speed must not be 
such as to rupture the paper web. Hence, while the oriented film can 
tolerate high speeds, the speed cannot exceed that which can be tolerated 
by the paper web. 
The products of the present invention, made in accordance with the methods 
set forth above, include release backings and liners for containers and 
surfaces which contact sticky or tacky foodstuffs or industrial 
compositions or compounds. In addition, the present invention also 
provides labels, containers, and surfaces which include a release backing 
or liner. According to an embodiment of the invention, a combination label 
and release backing is provided wherein the label has an adhesive surface 
on one side thereof in contact with the backing. The adhesive surface on 
the label may be a conventional pressure sensitive adhesive. The backing 
comprises a polymeric material layer which includes a first surface having 
a substantially uniform, smooth silicone coating formed thereon. The 
backing also comprises an adhesive layer and a cellulosic material layer, 
wherein the adhesive layer is disposed between the polymeric material 
layer and the cellulosic material layer to adhere them together. The 
smooth silicone coating of the polymeric layer contacts the adhesive 
surface of said label. 
According to another embodiment of the invention, a label and backing 
combination is provided as described above wherein the label is 
substantially transparent. In more preferred embodiments, the combination 
includes a silicone-coated oriented PET layer as the polymeric layer, 
and/or the cellulosic layer comprises a thin kraft paper. 
According to yet another embodiment of the invention, a combination 
container or surface having a release liner thereon is provided. The 
container or surface is particularly well-suited for applications where 
the liner comes in contact with sticky or tacky foodstuffs or industrial 
compounds or compositions such as resins. The release liner used in such a 
combination may be identical to the label release backings of the 
invention described above, but may alternatively have a greater thickness 
of one or more of the layers. Also, the release surface of such liners 
does not need to be as smooth as the surface of a release backing for a 
transparent label, but should nonetheless be smooth enough to prevent any 
substantial sticking of a foodstuff or industrial compound thereto. The 
use of such release liners minimizes waste of foodstuffs or industrial 
compounds which come in contact therewith, and are particularly 
well-suited for use as fiber drum liners and as pizza boxes or pizza box 
liners or tray inserts. 
According to yet another embodiment of the invention, the cellulosic 
material layer to be laminated comprises a fiberboard drum sidewall 
material which is used to make fiberboard drums. Although a release liner 
according to the invention can be inserted into a fiberboard, the drum 
itself may be made by forming a laminated structure according to the 
invention, e.g., rolling the structure into a drum. The resultant 
fiberboard drum has a release liner surface provided by the 
silicone-coated polymeric layer which had been previously laminated to the 
fiberboard material. Much thicker cellulosic layers are used according to 
this embodiment of the invention and include cellulosic layers having 
thicknesses of from about 10 to about 1000 mils, with thicknesses of 
between about 100 and about 500 mils being more preferred for many 
fiberboard drum applications. 
Referring to the FIGURE, a side view of an exemplary device and process are 
depicted for carrying out a preferred embodiment of the invention and for 
forming a laminated structure according to the invention. According to the 
embodiment shown, a polymeric layer in the form of a film, sheet, or web 
10 is laminated to a cellulosic layer supplied in the form of a sheet or 
web 12. For testing purposes, web widths of about 30 inches may be used at 
run speeds of up to about 600 feet per minute. On full-size manufacturing 
lines, webs having standard widths of about 80 inches or 120 inches may be 
employed and run at line speeds of about 1000 or 2000 feet per minute, 
respectively. For the purpose of clarity, the relative thicknesses of 
layers 10 and 12 shown in the FIGURE have been greatly exaggerated. 
The polymeric layer 10 may be fed from a supply (not shown) such as a roll, 
or preferably produced by in-line silicone coating of a freshly drawn 
polymeric film. The polymeric layer 10 has a release surface 14 comprising 
a silicone coating prepared by hydrolyzing a glycidoxy silane in deionized 
water and blending with an aqueous silicone resin emulsion and its 
corresponding crosslinker. Opposite the surface of the polymeric layer 
having the silicone coating 14 thereon, the polymeric layer has a 
laminating surface 16, which may be treated by a corona discharge device 
18 prior to lamination. Commonly available and many existing laminating 
systems have a corona treatment device 20 for treating the film surface 
opposite the laminating surface. The device 20 may be turned off to avoid 
destruction of the silicone coating 14. When water-based laminating 
adhesives are used, corona discharge treatments may be used to improve 
wet-out characteristics of the adhesive onto the polymeric laminating 
surface, so long as the treatment does not substantially destroy the 
silicone coating opposite the laminating surface. 
The polymeric layer 10 and the cellulosic layer 12 may be fed to a 
laminating compression nip 22 formed by two compression rollers 24 and 26. 
Compression roller 26 is provided with cooling means such that the roller 
is a chill roller in addition to being a compression roller. As the 
polymeric layer 10 passes around compression roller 24, but before it 
reaches the compression nip 22, a hot melt adhesive 28 is applied to the 
surface of the polymeric layer from an adhesive applicator die 30. An air 
gap 32 is provided between the distal tip 33 of the adhesive die nozzle 
and the laminating surface 16 of the polymeric layer where the adhesive 
first contacts the laminating surface. 
As the polymeric layer and cellulosic layer with the adhesive therebetween 
pass through the compression nip 22, the layers are adhered and laminated 
to each other to form a laminated structure 34. At the point of lamination 
and/or immediately thereafter, structure 34 is passed around chill roller 
26 to cool the hot melt adhesive 28 and minimize or prevent heat 
distortion of the silicone-coated polymeric layer 10. Chill roll placement 
"immediately" after the compression nip includes locations adjacent but 
spaced from the nip, for example, with one or more separate chill rolls. 
However, the path length of the multi-layered structure should not be too 
long as to allow heat distortion of the polymeric layer by the hot 
adhesive prior to being chilled. Preferably, the chill roll is maintained 
at ambient temperature or at about 72.degree. F. The clockwise direction 
of rotation of the roller 26 is shown by arrow 36. Roller 24 rotates in an 
opposite counterclockwise direction. 
When hot melt adhesives are used having melting ranges which are lower than 
the Tg of the polymeric film, immediate chilling of the laminated 
structure may not be needed. 
An uptake roll (not shown) for the laminated structure 34 is provided, the 
rotational speed of which dictates the laminating speed and the speed of 
supply of the two layers. The adhesive applicator die may be controlled 
based on the desired coating weight and the lamination speed. The die is 
controlled to apply an appropriate adhesive amount of adhesive for 
laminating and bonding. 
The present invention is further illustrated by the following non-limiting 
examples wherein all parts, percentages and ratios are by weight, and all 
temperatures are in .degree.F. unless otherwise indicated: 
EXAMPLES 1 AND 2, CONTROLS 1-4, AND COMISON 1 
Experiments were conducted to determine the force required to release 
labels and tapes from the silicone-coated surfaces of various 
non-laminated controls, inventive laminates, and a comparison laminate. 
Process conditions for each sample were varied to analyze the effects of 
the various conditions on releasability. 
Each of Controls 1-4, Examples 1 and 2, and Comparison 1, was processed on 
a 30 inch wide pilot line wherein the respective silicone-coated PET film 
roll is unwound and subjected to a set of processing conditions. The 
conditions which were varied included line speed, minimum path length, 
corona treatment, pre-heating, laminate paper weight, and idler roller 
lock-up. 
For each control, example and comparison, the silicone-coated PET film was 
supplied as a pre-manufactured roll. The rolled film was formed by an 
in-line process wherein the PET film had been drawn, uniaxially stretched 
in the machine direction to about 3.7 times its pre-stretched length, 
coated with a glycidoxy silane silicone coating composition, and then 
stretched in the transverse direction to about 3.7 times its pre-stretched 
width. The PET films used in Controls 1-4, Examples 1 and 2, and 
Comparison 1 each had a silicone coating thickness of from about 750 
angstroms to about 1500 angstroms. 
For inventive Examples 1 and 2, and Comparison 1, the silicone-coated PET 
film was laminated in-line to a bleach Kraft paper by an apparatus and 
method as shown in the drawing FIGURE. Lamination involved extruding a hot 
melt resin adhesive comprising a low density polyethylene available as 
NOVAPOL LC-0717-A, from Novapol LD division of Novacor Chemicals, Inc., 
Calgary, Alberta, Canada. NOVAPOL LC-0717-A has a melt index of about 7.5 
and a density of about 0.917 g/cc. 
In Example 2 shown in Tables I and II below, a 40 pound per ream natural 
Kraft paper was used as the cellulosic layer and the PET film was supplied 
from a secondary unwind position. The paper was supplied as a roll from 
the primary unwind position such that the minimum path length of the paper 
was about 15 feet less than the minimum path length of the PET film. In 
each of Example 1 and Comparison 1, the paper roll occupied the secondary 
unwind position while the PET film roll occupied the primary unwind 
position. 
Controls 1-4 were non-laminated silicone-coated polyethylene terephthalate 
films processed according to the conditions shown in Tables I and II 
below. The silicone-coated PET film of Control 1 was fed through the 
testing apparatus at a line speed of 500 feet per minute. After line 
feeding was complete, the release surface of the film was tested to obtain 
a base line release force reading. 
During the travel of Control 2 through the apparatus, the surface of the 
PET film opposite the silicone-coated surface was corona discharge treated 
at a rate of 0.5 watt per square foot per minute. The PET film of 
Comparison 1 was subjected to the same corona treatment as the PET film of 
Control 2, but in Comparison 1, the PET film was subsequently laminated to 
a bleached Kraft paper having a weight of 40 pounds per ream. For 
Comparison 1, the corona treated surface was the laminating surface. 
Control 3 in Tables I and II was passed through a 275.degree. F. primer 
heater zone at a rate of 20 feet per minute to heat and soften the film. A 
line speed of 20 feet per minute was used to ensure thorough heating of 
the film. 
The feed path for the Control 4 sample led the film around an intentionally 
locked-up idler roller such that the silicone-coated surface of the PET 
film rubbed on the roller. In this respect, Control 4 mimics conditions in 
a full production paper mill. If the present invention is adapted to such 
a system, the silicone-coated surface may pass over locked idlers which 
may have an affect on release from the coated surface. 
The release forces shown in Tables I and II were determined using adhesive 
labels or tapes made by applying an acrylic-based adhesive to the release 
surface of the silicone-coated PET film and thereafter applying paper 
strips, 2 inches wide by 12 inches long, as label material which picks up 
the adhesive. The force required to pull the paper strip from the release 
surface was measured using a TLMI release tester operating at a high-speed 
pull rate of 400 inches per minute. Such high-speed release conditions 
approximate labeling conditions in a mass production assembly line 
facility. The results shown are forces per two-inch width. The release 
forces shown in Table I below are those required to peel the test labels 
from the sample backing strips and were measured immediately (initial) 
under room temperature conditions and immediately under Kiel conditions 
(140.degree. C.). 
In Table I below, a release of greater than 500 grams per two inches 
indicates that the release of the test label was so tight that the 
measured value was off the scale and the load cell shorted out. 
TABLE I 
__________________________________________________________________________ 
INITIAL LABEL RELEASE VALUES (grams per 2 inch width) 
RELEASE 
KIEL 
MANUFACTURING CONDITIONS RELEASE 
CONDITIONS 
line corona 
primer 
bleach 
idler 
ROOM TEMP 
(140.degree. C.) 
speed secondary 
treat 
dryer 
Kraft roll stnd. stnd. 
Experiment 
(fpm) 
laminated 
unwind 
.5 watt 
275.degree. F. 
Paper (wt.) 
locked 
mean 
dev. 
mean 
dev. 
__________________________________________________________________________ 
Control 1 
500 
no 54.1 
1.1 
57 5.7 
Control 2 
500 
no X &gt;500 
N/A 
&gt;500 
N/A 
Control 3 
20 
no X 55.1 
3.4 
71.9 
6.7 
Control 4 
500 
no X 58.3 
2.5 
59.9 
1.2 
Example 1 
500 
yes #20 90.9 
3.2 
91 7.5 
Example 2 
500 
yes X #40 174.5 
23.5 
157.1 
4.8 
Comparison 
500 
yes X #20 &gt;500 
N/A 
&gt;500 
N/A 
__________________________________________________________________________ 
Next, more samples of Controls 1-4, Examples 1 and 2, and Comparison 1 were 
tested after one week aging under room temperature conditions, and after 
one week aging under Kiel conditions. The results of the release force 
tests after the one-week aging are shown in Table II below. In Table II, 
WELD means that after the test label was applied to the release surface of 
the sample, it was not separable from the release surface. Also, a release 
of greater than 500 grams per two inches indicates that the release of the 
test tape was so tight that the measured value was off the scale and the 
load cell shorted out. As in Table I, release values in Table II were 
measured per two inch width with a TLMI release tester operating at a pull 
rate of 400 inches per minute. 
TABLE II 
__________________________________________________________________________ 
LABEL RELEASE VALUES AFTER ONE-WEEK AGING (grams per 2 inch width) 
RELEASE 
KIEL 
MANUFACTURING CONDITIONS RELEASE 
CONDITIONS 
line corona 
primer 
bleach 
idler 
ROOM TEMP 
(140.degree. C.) 
speed secondary 
treat 
dryer 
Kraft roll stnd. stnd. 
Experiment 
(fpm) 
laminated 
unwind 
.5 watt 
275.degree. F. 
Paper (wt.) 
locked 
mean 
dev. 
mean 
dev. 
__________________________________________________________________________ 
Control 1 
500 
no 53.1 
1.1 
51.7 
1.0 
Control 2 
500 
no X WELD 
N/A 
WELD 
N/A 
Control 3 
20 
no X 53.7 
2.1 
54 1.7 
Control 4 
500 
no X 55.3 
1.5 
53.5 
1.3 
Example 1 
500 
yes #20 87.2 
6.1 
87.9 
4.3 
Example 2 
500 
yes X #40 141.9 
5.3 
139.8 
9.5 
Comparison 
500 
yes X #20 &gt;500 
N/A 
WELD 
N/A 
__________________________________________________________________________ 
For the two inch wide tape used to achieve the release force results in 
Tables I and II, release values of under 200 grams per two inch width are 
acceptable for release backing applications. Good release is found with 
release values of less than 160 grams per two inch width. Release values 
of less than 120 grams per two inches are preferred and values of less 
than 100 grams per two inches are even more preferred. These values are 
applicable to initial and one week aged samples at room temperature and 
under Kiel conditions. 
As can be seen from Tables I and II, the inventive laminates of Examples 1 
and 2 exhibited acceptable and preferred release force values indicating 
that the exemplary embodiments tested would make excellent release 
backings and liners, particularly for pressure sensitive adhesive labels. 
The laminated structures offer excellent release values while at the same 
time providing printability, excellent tear resistance, stiffness and 
moisture barrier properties. It is believed that the stiffer 40 pound per 
ream paper used in Example 2 was the major cause for the higher release 
force as compared to the release force obtained in Example 1 where thinner 
20 pound per ream paper was employed. It is further believed that the 
secondary unwind position of the film had little or no affect on the 
release of Example 2. 
Control 2 and Comparison 1 were the only experiments shown in Tables I and 
II wherein the surface of the PET layer was corona discharge treated 
opposite the silicone-coated surface. As can be seen in Tables I and II, 
the release properties of Control 2 and Comparison 1 were unacceptable in 
that their release force is greater than 500 gms per two inch width or the 
silicone-coated surface welded to the test tape. The corona treatment 
affected the release properties of the silicone-coated surface such that 
the laminated backing structure was extremely difficult to separate or 
inseparable from the applied adhesive test label. The corona treatment, 
even at just 0.5 watt per square foot per minute, substantially 
deleteriously affected the silicone coating on the opposite surface of the 
PET film and thus adversely affected the release properties of the release 
surface. Hot melt adhesives adequately wet-out on the PET film thus 
obviating the need for a corona discharge treatment and eliminating the 
risk of silicone-coating destruction as demonstrated by Examples 1 and 2. 
As can be seen from the release of Control 3 in Tables I and II, the 
preheating at 275.degree. F. had very little effect on release. It was 
also observed that preheating decreased surface smoothness due to heat 
distortion and wrinkling of the polymeric film. 
The results of Control 4 in Tables I and II show that release from the 
silicone-coated surface was not substantially affected by passing the 
surface over a locked-up idler roller. No substantial destruction of the 
silicone coating occurred, as evidenced by the excellent release values. 
The silicone coating acts as a lubricant to enable smooth gliding of the 
coated polymeric film over the locked roller, without substantially 
rubbing off or otherwise destroying the coating. Thus, the results 
indicate that the processes of the present invention may be performed on 
conventional paper mills without substantially adversely affecting label 
release. 
EXAMPLES 3 AND 4, CONTROLS 5-8, AND COMISON 2 
Examples 3 and 4 involved testing the force required to release a one-inch 
wide adhesive test tape at a slow speed from the laminated structures of 
the present invention, and the effects various process conditions have on 
release of the test tape. The manufacturing conditions and results are 
reported in Table III below. The backing materials for Controls 5-8 were 
the same as the backing materials for Controls 1-4, respectively. The 
backing materials for Examples 3 and 4 were the same as the backing 
materials for Examples 1 and 2, respectively. The backing material for 
Comparison 2 was the same as the backing material for Comparison 1. 
However, for each of Controls 5-8, Examples 3 and 4, and Comparison 2, the 
release forces shown in Table III were determined with an Instron 
measuring device designated Model TM, serial no. 2335, using a 1 inch wide 
TESA 7475 adhesive release test tape. Also, a pull rate of 12 inches per 
minute instead of 400 inches per minute was employed. Such low speed 
release rates approximate a manual peel of a label from a release backing. 
The Instron measurements were made within about 20 minutes of production 
of the backing material (off-machine) and under initial Kiel conditions. 
TABLE III 
__________________________________________________________________________ 
INITIAL LABEL RELEASE VALUES (grams per one inch width) 
RELEASE 
RELEASE 
KIEL 
MANUFACTURING CONDITIONS OFF- CONDITIONS 
line corona 
primer 
bleach 
idler 
MACHINE 
(140.degree. C.) 
speed secondary 
treat 
dryer 
Kraft roll stnd. stnd. 
Experiment 
(fpm) 
laminated 
unwind 
.5 watt 
275.degree. F. 
Paper (wt.) 
locked 
mean 
dev. 
mean 
dev. 
__________________________________________________________________________ 
Control 5 
500 
no 11.8 
0.5 
94.1 
2.4 
Control 6 
500 
no X 84.4 
18.8 
490.1 
1.3 
Control 7 
20 
no X 14.0 
1.0 
95.7 
2,8 
Control 8 
500 
no X 14.7 
0.8 
43.7 
10.1 
Example 3 
500 
yes #20 15.0 
2.4 
44.4 
13.1 
Example 4 
500 
yes X #40 15.9 
0.8 
41.8 
12.3 
Comparison 
500 
yes X #20 34.0 
6.1 
443.4 
35.8 
__________________________________________________________________________ 
When release testing is conducted with a one inch wide TESA 7475 test tape, 
initial release values of less than 20 grams per inch are preferred for 
room temperature samples and values of less than 50 grams per inch are 
preferred for samples tested under Kiel conditions. More preferable 
release values under Kiel conditions are values less than 45 grams per 
inch. 
The results of Control 6 and Comparison 2 indicate that a pre-lamination 
corona treatment of as little as 0.5 watt per square foot per minute 
adversely affects the silicone coating opposite the treated 48 gauge PET 
surface, but release remains possible with the one-inch wide TESA test 
tape. 
It was observed that although a very minor amount of heat shrinkage 
occurred in the experimental samples tested under Kiel conditions and 
shown in Table III, only Control 7 which involved a preheat step exhibited 
a heat-distorted film surface. 
Control 6 in Table III was also tested after a 24 hour ambient aging of the 
sample. The mean release force after 24-hour aging was reduced to 44.9 
grams per inch from an initial value of 84.4 grams per inch for the same 
control. The standard deviation from the 24-hour aging mean value was 6.9. 
The foregoing results for Examples 1-4 demonstrate that the use of a hot 
melt adhesive in combination with a chill roll provides advantageous 
results when laminating a silicone-coated polymeric layer to a cellulosic 
layer. The combination provides an integrally laminated structure having a 
low surface energy release surface without the need for a corona discharge 
treatment to effect a uniform wet-out of the laminating adhesive. Without 
the need for a corona treatment of the laminating polymeric surface prior 
to lamination, destruction of the silicone coating opposite the laminating 
surface is avoided. 
As can be seen from the Tables above, Examples 1-4 showed excellent release 
values in a thin, inexpensive, in-line laminated structure. The release 
properties of the laminates of Examples 1-4 demonstrate that they are 
excellent for release liner, release backing, and other non-stick low 
surface energy applications. 
Water-based adhesives could also be used as a laminating adhesive but 
corona treatment to improve adhesive wet-out on the PET film laminating 
surface should be conducted at a low level, for example up to about 0.2 
watt per square foot per minute for a 48 gauge silicone-coated PET film, 
to improve wettability of the aqueous adhesive without deleteriously 
affecting the silicone coating opposite the corona-treated surface.