Method and apparatus for forming an isotropic self-adhering elastomeric ribbon

Apparatus and method for extruding and cooling self-adhering elastomeric materials to obtain substantial uniform consistency. This is accomplished by bisurfacially exposing the material to cooling while supporting the material as a foraminous means.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to apparatus and method for forming 
extruded ribbons of self-adhering elastomeric material. 
2. Description of the Related Art 
Extruded ribbons of self-adhering elastomeric materials recently have come 
into commercial usage, in applications where the self-adhesive character 
of such materials is advantageously employed, e.g., in products such as 
disposable diapers, and in shoe covers where the ribbons are used, wherein 
these ribbons are utilized as elastic gathers around leg openings, as foot 
opening gathering means and anti-skid strips on the soles thereof. 
The elastomeric materials from which such ribbons are extruded may be 
self-adherent per se or may be rendered self-adherent by, for example, the 
addition of tackifiers to the elastomeric material prior to hot-melt 
formation and extrusion thereof in ribbon form. Illustrative self-adhering 
elastomeric materials include those described in U.S. Pat. No. 4,418,123 
to Bunnelle, et al., incorporated herein by reference. Commercially 
available materials of such type include FULLASTIC.RTM. adhesive elastic 
as available from H. B. Fuller Company. 
A problem which has arisen in the production of extruded ribbons of such 
self-adherent elastomeric materials has been the nonuniformity of physical 
properties arising from the method of cooling the extrudate ribbons. Such 
cooling typically has been carried out by passing the hot-melt extrudate 
of the elastomeric material onto the outer cylindrical surface of a 
rotating chill roll. The chill roll may be internally cooled or 
alternatively may be mounted in partially submerged position in a water 
bath, to effect dissipation of heat from the ribbon on the chill roll 
outer cylindrical surface. The cooling of the extrudate ribbon by means of 
such chill roll systems yields nonuiform properties, e.g., tack and 
dynamic adhesion, across the thickness of the ribbon, due to the 
preferential cooling of one side thereof. The prior art has proposed 
various approaches to cooling of extrudate and hot-melt materials, but the 
same are characterizable by deficiencies in application to self-adhering 
elastomeric ribbon materials. 
U.S. Pat. No. 3,175,026 to A. L. James discloses a system for extrusion of 
thermoplastic film materials such as polyethylene, in substantially fluid 
condition onto a cooled arcuate surface and then into a nip formed with an 
adjacent arcuate surface to form sheets of uniform gauge. The sheet thus 
is cooled to solidified condition while advancing in surface contact over 
the arcuate surfaces, both of which are smooth and glossy, one being 
relatively deformable. The arcuate surfaces, both of which may be cooled, 
advance at a faster rate of speed than the rate of extrusion to pull the 
sheet of fluid thermoplastic material from the extrusion source. 
A specifically disclosed embodiment in the patent comprises a cooled 
metallic cylinder cooperating with a draw roll and rotated therewith or 
independently driven at the same peripheral speed in opposite directions. 
The film of thermoplastic material solidified on the cooling cylinder is 
withdrawn therefrom by means of guide rolls to a final winding station 
where the film material is wound into a roll. The patent also discloses an 
embodiment which utilizes in place of the draw roll an endless backup belt 
mounted on a series of drive rollers and positioned in contact with the 
cooling cylinder to support the thermoplastic film about a portion of the 
periphery thereof (column 5, lines 35-37). The patent discloses the use of 
a hollow internally cooled drum to constantly cool the surface of the belt 
to prevent overheating thereof. 
The method and apparatus of the James patent utilizes arcuate conveying 
surfaces of different materials and different sizes (the draw roll or 
endless belt providing a smaller extent of thermoplastic film-contacting 
surfaces than the cooling cylinder) so that primary cooling and 
solidification is effected on the cooling cylinder. The thermoplastic 
sheet material in the James system thus is subjected to intrinsically 
dissimilar rates and ranges of cooling on its respective opposite 
surfaces, consistent with the teaching in the patent at column 4, lines 
38-41 that "it has been found desirable to extrude the curtain onto the 
cooled arcuate metallic surface of the drum 8 and then to the nip in 
actual practice to quickly cool the film." Accordingly, even if the system 
were modified to obtain the same heat transfer rates on both surfaces of 
the film in the nip between the cylinder and draw roll or belt, the 
thermoplastic material would already have been subjected to a preliminary 
cooling on one surface prior to concurrent cooling of both surfaces. 
U.S. Pat. No. 2,590,186 to E. H. Land discloses a method of forming a solid 
film on the surface of a sheet-like material from a viscous liquid mass of 
the film-forming material. Sheet-like materials are fed along conveying 
paths with viscous liquid being fed to the sheets to provide a body of 
liquid therebetween. At least one of the sheets is absorbent of the 
solvent for the film-forming material, so that a substantial amount of 
drying of the formed film takes place rapidly due to such solvent 
absorption. When drying has reached a point where the film is a 
substantially continuous solid, at least one of the sheets is separated 
from the forming film and continued drying takes place due to evaporation 
of remaining solvent from the exposed surface of the film. The patent 
discloses in column 4, lines 55-67 to pass the supporting sheets having 
the film-forming material therebetween, through an oven at elevated 
temperature, or alternatively to expose them to dry hot air, infrared 
lamps, etc., to enhance the removal of solvent from the film-forming 
composition. 
U.S. Pat. No. 3,852,387 to N. M. Bortnick, et al. discloses using paired 
endless belts for forming extruded polymer melts into thermoplastic 
sheets. A strand of extruded polymer melt is taken up between the moving 
belts at a temperature that allows the melt to adhere to the belts while 
being formed into a web by compression, spreading and flattening 
therebetween. The endless belts preferably utilize smooth, polished 
metallic surfaces to produce flat, optical quality thermoplastic sheet. 
A plurality of compressed air knives are spaced intermediate the runs of 
the belts to enhance cooling of the thermoplastic material, if ambient 
cooling proves inadequate, to a temperature allowing parting of the 
product sheet without adherence to either belt. 
SUMMARY OF THE INVENTION 
In one aspect, the present invention relates to apparatus for forming a 
self-adhering elastomeric ribbon, comprising means for extruding a 
hot-melt self-adhering elastomeric material in ribbon form, and foraminous 
means for conveying the extrudate ribbon away from the extruding means, 
with the extrudate ribbon bisurfacially exposed for cooling thereof. 
A further aspect relates to such foraminous means as bisurfacially 
supporting the extrudate ribbon while conveying same away from the 
extruding means. 
In another aspect, the invention relates to apparatus of the 
above-described type, further comprising means for bisurfacially cooling 
the extrudate ribbon while it is being conveyed by the foraminous means. 
In another aspect, the invention relates to apparatus of the aforementioned 
type, wherein the means for bisurfacially cooling the extrudate ribbon 
comprises means for directing a coolant fluid against both surfaces of the 
extrudate ribbon. 
Another aspect of the present invention relates to a method for forming a 
self-adhering elastomeric ribbon comprising extruding a hot-melt 
self-adhering elastomeric material in ribbon form, and conveying the 
extrudate ribbon away from the extruding step, with the extrudate ribbon 
bisurfacially exposed for cooling thereof. 
Still another aspect of the invention relates to a method of the above 
type, further including bisurfacially supporting the extrudate ribbon 
while conveying same away from the extruding step. 
In yet another aspect, the invention relates to a method of the 
aforementioned type, further comprising bisurfacially cooling the 
extrudate ribbon while it is being conveyed away from the extruding step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As indicated hereinabove, a specific problem associated with the prior art 
practice of cooling extruded self-adherent elastomeric materials on a 
chill roll is that the resulting extrudate article has nonuniform 
properties due to the uneven rate and extend of cooling. When ribbon-form 
extrudates are quenched, there is a two-sided effect on tack, tensile 
strength, stress relaxation, and dynamic adhesion. The two-sided tack 
effect is particularly detrimental to the desired uniform self-adhering 
character of the elastomeric ribbon. The chill roll cooling yields 
significantly less tack on the surface of the ribbon which contacts the 
chill roll than the side away from the chill roll. 
The present invention provides for conveying the extrudate ribbon of 
hot-melt self-adhering elastomeric material away from the extruding means, 
the ribbon being bisurfacially exposed for cooling. Such cooling may be 
selected by simple exposure of the extrudate ribbon to the ambient 
conditions, if same are sufficient to effect such cooling of the ribbon. 
Alternatively, it may be useful in the broad practice of the present 
invention to utilize specific means for bisurfacially cooling the 
extrudate ribbon. It is advantageous in many instances to carry out the 
present invention by bisurfacially supporting and conveying the extrudate 
ribbon away from the extruding step. 
As used herein, the term "bisurfacially" in reference to supporting, 
conveying, and/or cooling the extrudate ribbon means that the extrudate 
ribbon is supported, conveyed and/or cooled simultaneously on both main 
surfaces of the ribbon, i.e., the top and bottom surfaces of the ribbon, 
when the ribbon is disposed on a horizontal surface. By such bisurfacial 
cooling, optionally suitably carried out with bisurfacial supporting and 
conveying of the extrudate ribbon, the extrudate ribbon of self-adhering 
elastomeric material is effectively cooled to yield a product elastomeric 
ribbon which is isotropic, i.e., substantially uniform in its physical 
properties throughout its entire volume, as compared to a corresponding 
elastomeric ribbon which is monosurfacially cooled. 
The elastomeric materials which may be useful in the broad practice of the 
present invention include hot-melt elastomeric materials such as natural 
or synthetic rubbers, blends of natural and synthetic rubbers, synthetic 
elastomeric resins, combinations of natural rubber and synthetic resins, 
as well as any other composition generally useful in the manufacture of 
elastomeric self-adherent ribbons by hot-melt extrusion. As indicated 
previously herein, the self-adhering elastomeric ribbon may be 
self-adhering per se, or may be an elastomeric material of any of the 
above-mentioned types to which is added, prior to or during extrusion, a 
tackifier of conventional type. A preferred class of materials include 
elastomeric hot-melt adhesive (self-adhering elastic) materials of the 
type disclosed and claimed in U.S. Pat. No. 4,418,123 to Bunnelle, et al., 
incorporated herein by reference. Particularly suitable materials are 
thermoplastic synthetic resin and rubber block copolymer compositions, as 
utilized in the FULLASTIC.RTM. extruded self-adhering elastic. 
Referring to the schematically illustrated process system according to one 
embodiment of the invention as shown in FIG. 1, the hot-meltable 
self-adhering elastomeric material 101, in particulate form or in the form 
of a (heat) flowable resin, is fed from hopper 102 into extruder 103, 
which may be a screw-type extruder of conventional type wherein the 
extrusion screw is coupled by drive shaft 104 to drive motor 105. From the 
extruder 103, wherein the elastomeric material is processed as a hot melt 
under conditions of elevated temperature and pressure, the material passes 
via transfer conduit 106 into manifold 107 for introduction into the 
slotted die 108 featuring die orifice 109, from which the hot-melt 
elastomeric material is discharged in the form of an extrudate ribbon 110. 
The extrudate ribbon 110 then passes to an assembly for bisurfacially 
supporting the extrudate ribbon and conveying same away from the extrusion 
apparatus comprising die 108, manifold 107 and extruder 103. More 
specifically, the extrudate ribbon 110 is engaged simultaneously between 
opposedly facing foraminous belts 11 and 12 on their opposed faces 13 and 
14, respectively. The foraminous belts 11 and 12 are each mounted on 
rolls, foraminous belt 12 being mounted on rolls 15 and 17, in turn 
mounted on shafts 19 and 21, respectively. Foraminous belt 11, which is of 
endless form, is translated so that face 14 thereof is translated 
downwardly in the position shown. In like manner, foraminous belt 11 is 
mounted on rolls 16 and 18, in turn mounted on shafts 20 and 22, 
respectively, whereby the face 13 of belt 11 is downwardly translated in 
the position shown. The rolls associated with each foraminous belt include 
a drive roll, e.g., the rolls 15 and 16 mounted on shafts 19 and 20 may be 
coupled to suitable drive means (not shown) whereby the respective rolls 
are driven in counter-directional rotation to one another, in the 
direction of the arrows shown on such rolls in the drawing. In such 
manner, the opposed faces 13, 14 of the opposedly facing foraminous belts 
11, 12, respectively, are unidirectionally translated for conveying of the 
extrudate ribbon 110 away from the extruding means. 
The foraminous belts may be of any suitable material of construction, such 
as ferrous alloys or other metals, ceramics, composites, plastics, etc., 
with materials such as stainless steel being suitable. 
The foraminous belts suitably may be coated on their outer surfaces 
(opposed faces) 13 and 14 with a release agent to oppose adhesion of the 
extrudate ribbon thereto or otherwise may be provided with a surface or 
surface coating which is adhesion-free in respect of the extrudate ribbon. 
Thus, for example, a non-stick coating surface may be provided on the 
foraminous belt, or the belt may be coated with a silicone material or 
other satisfactory release agent. 
The term "foraminous belt" as used herein and in the claims is intended to 
be broadly construed to include any and all suitable foraminous means 
which may be usefully employed for conveying the extrudate ribbon away 
from the extruding means, with the extrudate ribbon bisurfacially exposed 
for cooling. Thus, the foraminous means may be constituted by a 
reticulated foraminous web, grid, mesh, wire carrier or other structural 
element which is foraminous in character to bisurfacially expose the 
extrudate ribbon for cooling. It is a critical feature of the present 
invention that the extrudate ribbon is bisurfacially exposed for cooling 
by the foraminous means, to allow direct heat exchange with the main 
surfaces of the extrudate ribbon while it is being supported and conveyed 
by the foraminous means. Accordingly, it is preferred in practice that the 
open area of the foraminous means be as high as possible consistent with 
its function of supporting and conveying the extrudate ribbon. 
Depending on the material characteristics of the extrudate ribbon and the 
open area provided by the foraminous supporting and conveying means, it 
may be satisfactory in some instances to cool the extrudate ribbon at its 
bisurfacially exposed faces by simple exposure to ambient conditions. In 
most instances, however, it is generally more advantageous to utilize 
specifically provided cooling means for bisurfacially cooling the 
extrudate ribbon while it is being supported and conveyed by the 
aforementioned foraminous means, in order to insure close control and 
uniformity of the cooling step. Thus, the means for bisurfacially cooling 
the extrudate ribbon while it is being supported and conveyed by the 
aforementioned foraminous means may suitably comprise means for directing 
a coolant fluid, such as air, nitrogen or other fluid, at suitable 
temperature, against both surfaces of the extrudate ribbon. As used herein 
in respect to the cooling step, the term "bisurfacially cooling" means 
that the extrudate ribbon is cooled substantially equivalently at both 
main surfaces thereof, to a generally equivalent extend and at a generally 
equivalent heat transfer rate. 
In FIG. 1, the means 23, 24 for bisurfacially cooling the extrudate ribbon 
110 comprise a plurality of discharge nozzles 25, 26 and 27 associated 
with the foraminous belt 12 which are manifolded together by a conduit 31 
joined by a coolant fluid supply line 33 to a source of coolant fluid (not 
shown), and with discharge nozzles 28, 29 and 30 in like manner being 
manifolded together by conduit 32 joined by coolant fluid supply line 34 
to a suitable source of coolant fluid (not shown). The nozzles discharge 
coolant fluid against both surfaces of the extrudate ribbon, with the 
coolant flow streams discharged from the nozzles passing through the open 
areas in the foraminous belts to directly contact the respective main 
surfaces of the extrudate ribbon. In lieu of discharge nozzles, the 
cooling means may be constituted by air shrouds or vortex-producing means 
which direct a coolant fluid through the foraminous belts and against the 
main surfaces of the extrudate ribbon, or alternatively other suitable 
cooling means of conventional type as known in the art may be employed. 
Further, it may be desirable in some instances of the present invention to 
provide for enhancement of the bisurfacial cooling of the extrudate ribbon 
by provision of internal cooling in the rolls on which the foraminous 
supporting and conveying means are disposed, e.g., the drive rolls 15 and 
16, whereby the extrudate ribbon 110 as it enters the nip formed by rolls 
15 and 16 and their associated foraminous belts 12 and 11, respectively, 
may be subjected to initial bisurfacially cooling at high rate, followed 
by reduced bisurfacially cooling downstream from such nip along the 
foraminous belts. Thus, it is within the purview of the present invention 
to provide for stepwise or continuous gradient cooling of the extrudate 
ribbon in bisurfacial fashion while it is being supported and conveyed by 
the foraminous means. 
Subsequent to completion of the bisurfacial cooling of the extrudate 
ribbon, the product self-adhering elastomeric ribbon 35 is discharged from 
the process system in the direction shown by arrow 36, for downstream 
processing and/or end-use. 
FIG. 2 shows a schematic diagram of a process system for carrying out the 
present invention, according to another embodiment thereof. Corresponding 
system elements are numbered correspondingly with respect to FIG. 1, but 
with prime designations suffixed to the corresponding reference numerals. 
Thus, hot-meltable self-adhering elastic material flows through transfer 
conduit 106' into manifold 107' and then to die 108' containing orifice 
109' for discharge in the form of an extrudate ribbon 110'. The extrudate 
ribbon then is received by the top surface 50 of the foraminous belt 51 
for supporting and conveying the ribbon away from the extruding means. The 
foraminous belt 51 is of endless form, being mounted on rolls 52 and 54, 
mounted in turn on shafts 53 and 55, respectively. One of these shafts is 
suitably joined to a drive means, such as an electric motor (not shown) 
which rotates same in a clockwise direction to translate the ribbon 
through the cooling operation and away from the extruding means, as 
indicated. Thus, the top surface of ribbon 110' receives cooling fluid 
from the nozzles 58, 59 and 60 each of which is manifolded together by 
conduit 61 joined in turn to coolant source line 62, joined to a suitable 
source of coolant fluid (not shown). In like manner, coolant nozzles 63, 
64 and 65 are manifolded together by conduit 66 which in turn is joined to 
coolant line 67 joined to a source of coolant fluid (not shown), whereby 
coolant streams are directed at the bottom surface of the ribbon reposing 
on the foraminous belt 51. In such manner, the extrudate ribbon is 
bisurfacially exposed on the foraminous belt for cooling of both sides 
thereof. The product extrudate ribbon 35', bisurfacially cooled on its top 
surface 56 and its bottom surface 57 then is withdrawn from the foraminous 
belt by means of take-off roll 68 mounted on shaft 69, by means of which 
the ribbon is discharged from the process in the direction shown by arrow 
36' for further processing and/or end use. 
FIG. 3 is a plan view of a portion of the FIG. 2 system, taken along line 
3--3 thereof, showing the extrudate ribbon 110' being disposed on the top 
surface 50 of foraminous belt 51. The manifold conduit 61 as shown 
supplies coolant fluid to the nozzle 58, the latter extending transversely 
across the extrudate ribbon top surface 56, so that gas discharged from 
the nozzle 58 cools such top surface as the ribbon is translated in the 
direction shown by arrow 70. 
The embodiment shown in FIGS. 2 and 3, thus utilizes a single foraminous 
belt for conveying the extrudate ribbon away from the extruding means, 
with the extrudate ribbon bisurfacially exposed for cooling thereof. In 
systems of the type shown in FIGS. 2 and 3, wherein the extrudate ribbon 
is monosurfacially supported and conveyed with the extrudate ribbon 
bisurfacially exposed for cooling, it may be necessary to vary the coolant 
flow rate or other cooling parameters on either side of the ribbon to 
account or otherwise adjust for the heat transfer resistance imposed by 
the foraminous belt, i.e., it may be necessary to direct a higher flow 
rate of coolant fluid at the bottom surface to provide cooling thereof 
equivalent to cooling effected by coolant flow against the top surface, 
which is not supported by any foraminous belt. Such adjustments can 
readily be made without undue experimentation to realize bisurfacial 
cooling at the same rate of heat transfer and to the same extent of 
cooling on both sides of the extrudate ribbon. 
The self-adhering elastomeric ribbon product of the present invention may 
usefully be employed in elastic gathering strips to impart conformability 
to body portion openings in garments, such as for example dispossable 
diapers or undergarments, wherein close conformability to the actual size 
of the wearer's body is desired. 
The features and advantages of the present invention are shown by the 
following Example. 
EXAMPLE 
Four samples were made of self-adhering elastomeric ribbons to demonstrate 
the advantages of the present invention. All samples were made using as 
the hot-melt extruded elastomeric material, FULLASTIC.RTM. elastic, 
commercially available from H. B. Fuller Co. Samples 1-3 were extruded 
from a Brabender extruder using a 0.50 inch.times.0.020 inch flat die at 
190.degree. C. Sample 4 was extruded from a killion extruder using a 9/16 
inch.times.0.024 inch die at 190.degree. C. 
Sample 1 was cooled on a chill roll whose outer cylindrical surface was 
coated with a silicone coating to resist adhesion of the extrudate ribbon 
thereto, the chill roll having a diameter of two feet and a rotational 
speed of 10 rpm. The chill roll was cooled by partial immersion of the 
lower extremity thereof in a water bath maintained at room temperature 
(20.degree. C). This sample thus was monosurfacially cooled, with its top 
main surface having been translated through the cooling step in contact 
with the surface of the chill roll; the bottom main surface of the sample 
constituted the opposite surface of the ribbon, which did not contact the 
chill roll. 
Sample 2 was analogously cooled in the manner of Sample 1, but without 
water bath immersion of the chill roll. Thus, the top main surface of the 
sample was contacted during cooling with the dry surface of the chill 
roll, while the bottom main surface constituted the opposite surface which 
did not contact the chill roll. 
Sample 3 was bisurfacially cooled to simulate the present invention, 
without exposure to any water bath or chill roll cooling means. Instead, 
the respective top and bottom main surfaces of the extrudate ribbon were 
festooned onto separate sheets of release paper for cooling by exposure to 
ambient conditions. The release paper thus served as supporting and 
conveying means simulative of foraminous means, due to the extremely low 
heat transfer resistance of the release paper, i.e., simulative of 
exposure of the ribbon's main surfaces to ambient conditions. 
Sample 4 was monofacially cooled by exposure to a chill roll maintained at 
a temperature of 46.degree. F. The top main surface of the sample was 
cooled against the chill roll surface, while the bottom main surface of 
the sample was not in contact with the chill roll. 
The various test samples described above were subjected to determinations 
of their tensile strength, stress relaxation, dynamic adhesion and initial 
tack. The test procedures for these determinations were as follows. 
TENSILE STRENGTH 
Each sample was tested to determine the tensile strength in psi at 100% 
elongation under standard conditions. Each sample was conditioned for a 
minimum of 24 hours at standard conditions 73.5.+-.2.degree. F., 50%.+-.2% 
RH before testing. All testing was done at standard-condition atmosphere. 
The materials were cut into test ribbons approximately 4.0" long. Each 
ribbon was marked with two lines, 3.0" apart. The ribbon cross-sectional 
area was determined. The Instron testing device was calibrated and zeroed 
and set as below: 
Gage length: 3", 
Crosshead speed: 4"/min. (200 mm/min.), 
Test direction: up (down on older models), 
Flex correction: none, 
Optional chart speed: 2"/min. (50 mm/min.), 
Elongation (extension length): 3" (100%). 
The ribbon was placed into upper jaw with the marked line coincident with 
edge of clamping jaw edge. The bottom end of ribbon was placed into lower 
jaw and with the bottom line coincident with clamp edge. The cross head 
movement in test direction was actuated. Record this value and omit steps 
13 and 14 and the instantaneous tension pounds-force at 100% elongation 
(6" jaw separation). The stress was recorded. Compute in psi at 100% 
elongation by dividing tension at 100% elongation (pounds) by specimen 
cross-sectional area (sq. in.). 
CREEP RESISTANCE 
The creep resistance of the material was evaluated by determining the 
ability of a 0.5".times.0.020" by 4.00" ribbon to recover to its initial 
length after prolonged stretching at an elevated temperature. The material 
was cut into test ribbons approximately 5.0" long. The ribbons were marked 
with two lines 4.0" apart. A creep testing device (the Model Shop) was set 
so that the distance from edge of clamp to edge of opposing clamp was 
8.0".+-.0.01" the full open position distance. The tester was closed to 
allow a 3" gap between opposing clamp edges. The marked ribbons were 
clamped into test device, putting the marked lines exactly at the edge of 
the clamping surfaces. The ribbons were extended and locked in the 
extended (8" testing) position. The creep-testing device was placed into 
the preheated oven at 100.degree. F. in a horizontal position. Five (5) 
minutes was allowed for oven to equilibrate to test temperature 
(100.degree. F.) and held at that condition for four (4) hours. The 
creep-testing device was removed and placed on a horizontal surface. The 
ribbons were released to eliminate stress and transferred one at a time to 
a flat, nonstick surface and equilibrated for 15 minutes at standard 
conditions. After equilibration each ribbon was measured with a caliper 
while lying flat. The creep of each material was determined as follows: 
##EQU1## 
STRESS RELAXATION 
Each sample was tested to determine the rate of loss of elastic retraction 
force at 120.degree. F. and 30% elongation. The material was cut to 
approximately 3.0" lengths. Each ribbon was marked with two lines 2.0" 
apart. The test ribbon was clamped into nonslip holding clamps and 
equilibrated for fifteen (15) minutes at 120.degree. F. The ribbon was 
then extended to 2.6" (30% elongation), placed in an oven and readings 
were of elapsed time vs. force for two hours. A slope of log.sub.10 of 
time (abscissa) versus the log.sub.10 of force (ordinate) was determined 
and the antilog of the slope computed. The percent drop in force per 
dacade change in time is expressed as below: 
% drop in force per decade of time=[1.00-antilog (slope of log-log 
plot).times.100. 
STATIC ADHESION 
Each sample was tested to determine the adhesion between material and poly 
under static conditions. A 0.5".times.0.020" by 21/2" ribbon was sealed to 
1 mm poly for 2 seconds at 20 psi; then a 180.degree. peel was done using 
a 200 gram dead weight at 120.degree. C. The time of adhesion failure was 
recorded in minutes. 
DYNAMIC ADHESION 
Each sample was also tested to determine the dynamic adhesion value between 
material and poly. A 0.5".times.0.020" ribbon was sealed to 1 mm poly 
under 20 psi for 2 seconds and then a 180.degree. peel was done by 
dynamically pulling the material from the poly and the force required to 
do this was recorded. 
The test results of the aforementioned physical property determinations are 
set forth in Table 1 below: T1 TABLE I-SAMPLE? -TEST? 1? 2? 3? 4? -Tensile 
strength, psi 77 76 84 64 -Stress relaxation, % 12.0 12.2 11.2 15.6 
-Dynamic adhesion, avg. gm. 1195 1226 1309 728 -Initial tack, avg. gm. 
235 234 232 234 -Dynamic adhesion, top.sup.(1), gm. 1117 1183 1363 822 
-Dynamic adhesion, bottom.sup.(2), gm. 1272 1268 1255 634 -Dynamic 
adhesion, difference, gm. 155 108 85 188 -Initial tack, top.sup.(1), 
gm. 232 243 235 228 -Initial tack, bottom.sup.(2), gm. 238 224 228 
239 -Initial tack, difference, gm. 6 19 7 4 - 
FNT .sup.(1) top main surface of the extrudate ribbon. - 
FNT .sup.(2) bottom main surface of the extrudate ribbon. - 
The results shown in Table I demonstrate that Sample 3, prepared by a 
process simulative of the present invention, produced a ribbon product 
which had higher tensile strength, lower stress relaxation, higher dynamic 
adhesion and substantially equal initial tack, as compared to Samples 1, 2 
and 4, representative of the prior art production of self-adhering 
elastomeric extrudates. Further, as regards the two-sided effects of the 
cooling process, it is seen that the differential for Sample 3 between 
dynamic adhesion values measured at the main top and bottom surfaces was 
significantly lower than corresponding values for Samples 1, 2 and 4, 
which were monosurfacially cooled. 
As regards initial tack values measured at the main top and bottom surfaces 
of the respective ribbon samples, the differential measured for Sample 3 
was substantially less than that of Sample 2, which utilized monosurfacial 
exposure of the ribbon to a chill roll. Such differential for Sample 3 
also was generally consistent with the values measured for Samples 1 and 
4, Sample 4 using a low temperature chill roll and Sample 1 utilizing a 
chill roll disposed in a water bath. 
Although preferred embodiments of the present invention have been described 
in detail, it will be appreciated that other modifications and variations 
thereof, along with other embodiments, are possible and accordingly, all 
such apparent modifications, variations and embodiments are to be regarded 
as being within the spirit and the scope of the present invention.