Repositionable adhesive tape

An adhesive of certain elastomeric block copolymers and tackifying materials can be hot-melt coated onto a flexible backing to provide an adhesive tape, two pieces of which can bond to each other to have excellent resistance to shear forces but can be easily peeled apart, even after prolonged periods of time. The adhesive can be low-tack or tack-free. When the novel adhesive is tacky, it can bind sheets into a note pad from which individual sheets can be removed, temporarily adhered to paper and other substrates, and later cleanly removed, even after prolonged contact.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention is concerned with low-tack and tack-free adhesives that 
substantially do not experience adhesion build-up and so provide tapes 
that are repositionable, even after being adhered to a substrate for 
prolonged periods of time. Of special interest are low-tack 
pressure-sensitive adhesive note pads and adhesive diaper closures. 
2. Description of the Related Art 
POST-IT.TM. note pads have become virtually indispensable in the office, 
each sheet bearing a stripe of pressure-sensitive adhesive that is 
sufficiently tacky to adhere to paper and other substrates but does not 
show a buildup of adhesion. The sheets can be cleanly removed and 
reapplied a number of times without loss of tackiness. These attributes 
are realized due to the use of tacky microspheres coated onto the paper 
substrate, as disclosed in U.S. Pat. No. 3,691,140 (Silver). The same 
low-tack pressure-sensitive adhesive has been used for a number of other 
purposes, e.g. as a coating for a bulletin board or for posting ordinary 
pieces of paper. 
The widespread success of the POST-IT.TM. note pads and the relatively high 
cost of the adhesive have resulted in efforts to produce a 
pressure-sensitive adhesive of a more simple, and hence more economical, 
composition that would provide the same attributes. However, it is 
believed that every known pressure-sensitive adhesive has been deficient 
in some important respect, e.g., being too aggressively tacky or lacking 
the desired initial holding power or being subject to a gradual buildup in 
adhesion. 
An adhesive that is said to afford similar properties as that used in 
POST-IT.TM. note pads is the subject of U.S. Pat. No. 4,684,685 (Shuman et 
al.). Shuman et al.'s preferred adhesive includes a natural rubber latex 
and a tackifier which is an anionic aqueous dispersion of hydrogenated 
rosin or rosin esters. After coating the dispersion onto a substrate such 
as a sheet of paper, the dried coating allegedly has enough tack to adhere 
to solid contact surfaces by manually pressing the coated substrate to 
that surface. The Shuman patent says that the user can then "reapply the 
coated substrate as many as eight to ten additional times to the same or 
another free solid surface." 
Although there have been attempts at providing alternative adhesive 
formulations which provide properties suitable for use as a repositionable 
adhesive, such as for repositionable note pads, there is still great 
interest in the discovery of yet more alternatives. 
Of additional interest for repositional low-tack adhesives, and otherwise, 
are adhesives which adhere to themselves yet are subsequently removable 
and re-adherable. Adhesives with these properties may or may not have 
repositionable tape or note pad properties. Advantageously, for certain 
applications these self-adhering adhesives will be relatively non-tacky or 
have no tack so that they exhibit adhesiveness to little else other than 
itself. Examples of such adhesives are discussed in U.K. Pat. No. GB 
2,116,253B (Clerici et al. ) and U.S. Pat. No. 4,522,874 (Pommez). 
Clerici et al. releasably joins two objects using two pieces of "adhesive" 
tape that can be repeatedly engaged and disengaged. They state that this 
requires each of (a) the cohesive strength of the carriers, (b) the 
anchoring of the adhesive layers to the carriers, and (c) the cohesive 
strength of the adhesive layers to be stronger than the force required to 
separate two engaged tapes. The Clerici et al. adhesive can be coated from 
"an elastomer for example natural rubber dissolved in a solvent such as 
heptane in the proportions of 15% natural rubber and 55% of heptane, by 
weight" (sentence bridging pages 8 and 9). Also useful is "a mixture of 
elastomeric materials, consisting for example of natural rubber and 
elastomers of a synthetic nature, such as butadiene-styrene rubber" (page 
4, lines 17-24). The Clerici et al. "adhesive" is just rubber or a mixture 
of natural and synthetic rubber which is attached to an, e.g., cloth 
backing. 
Pommez illustrates a three-layer disposable diaper, the outer layer of 
which is "a porous paper-like substrate having one surface thereof coated 
with a selective adhesive which adheres only to itself" (col. 2, lines 
38-41). Referring to FIG. 2: "Ears, or projections 54, of the back portion 
of the diaper, are also impregnated with the adhesive of the invention 
from inside, which enables its selective adhesion in any position on the 
outer surface, also impregnated, of the front portion 56, of the diaper. 
The qualities of the invention's adhesive enable the fastening and 
refastening of ear 54 until a perfect fit on the wearer's body is 
obtained, or permits the diaper to be removed and used again later" (col. 
4, lines 1-11). "The adhesive is comprised of an aqueous ammoniacal 
emulsion having about 60 percent solids and about 0.003 percent ammonia. 
The solids are about 85 parts by weight poly-cis-isoprene and about 15 
parts by weight vinyl acetate and n-butyl acrylate" (col. 2, lines 41- 
45). 
This emulsion of Pommez serves as an adhesive and as the means by which the 
outer shell (paper) is made water impermeable. There is no indication that 
this emulsion would be suitable for use in a tape or on a diaper which is 
not a porous paper substrate, e.g. a polyolefin backing which would 
severely limit the applicability of this self-adhering adhesive. Further 
use of a solvent based system is hampered by the need to subsequently 
remove and properly dispose of the solvent. This problem is particularly 
acute where the solvent is a volatile organic, as in Clerici et al. 
The present invention has as a general object to solve or substantially 
alleviate the above noted problems in the art. 
Another object of the invention is to provide an adhesive composition that 
is self-adhering. 
A more specific object is to provide a self-adhering adhesive that can be 
subsequently removed and reapplied to itself. 
A more specific object is to provide a self-adhering adhesive which is 
suitable for use as a repositionable diaper closure. 
Another more specific object is to provide a self-adhering adhesive that 
has low or no adhesive buildup to itself. 
Another object is to provide a repositionable adhesive. 
A more specific object is to provide a repositionable adhesive which is 
adhesive to itself. 
A further object of the present invention is to provide a method for 
applying these adhesives without the use of a solvent. 
Further advantages and features of the invention, as well as the scope, 
nature and utilization of the invention will become apparent to those 
skilled in the art from the following description of the preferred 
embodiments of the invention. 
SUMMARY OF THE INVENTION 
The invention provides a low-tack or tack-free adhesive that can be coated 
onto a backing, generally flexible, to provide an adhesive tape, two 
pieces of which can bond to each other with excellent resistance to shear 
forces while still being easily peeled apart, even after prolonged periods 
of time. When the novel adhesive composition is low-tack, it is a 
pressure-sensitive adhesive and can have the attributes of the adhesives 
of the Silver patent, while being more economical to manufacture because 
it is hot-melt coatable and does not require tiny balls of a stiff 
pressure-sensitive adhesive or cause the environmental problems of solvent 
coating methods. Briefly, the novel adhesive comprises a composition of by 
weight: 
from 20 to 80 parts of at least one elastomeric block copolymer selected 
from styrene/butadiene, styrene/isoprene, and styrene/ethylene-butylene 
block copolymers, and 
correspondingly from 80 to 20 parts of tackifying material selected from 
tackifier resins or blends and blends of tackifier resin with liquid 
plasticizer oil, 
which adhesive can be hot-melt coated without the use of solvents and has a 
composite midblock glass transition temperature (CMTg) from 225 Kelvin to 
240 Kelvin when the adhesive is based on styrene/isoprene or 
styrene/ethylene-butylene block copolymers and a CMTg from 215 Kelvin to 
235 Kelvin when the adhesive is based on styrene/butadiene block 
copolymer. The CMTg can be calculated using the Fox Equation from the 
measured Tg of the midblock of the elastomeric block copolymer and the 
measured Tg of each tackifying resin and liquid plasticizer oil. The Tg 
for each component is measured using a differential scanning calorimeter 
such as a DSC-7, manufactured by Perkin-Elmer. The Tg is measured on the 
second heating run using a scan rate of 20 degrees Centigrade per minute. 
The first heating run is made up to well above the softening point of the 
test material. The sample is subsequently quenched to well below the Tg of 
the material. Antioxidants added to the adhesive are not figured into the 
calculation of the CMTg. 
##EQU1## 
where W.sub.i is the weight fraction of component i and Tg.sub.i is the 
glass transition temperature of component i. Only the midblock portion of 
the block copolymer is included in the calculation of the CMTg. For a 
styrene/isoprene block copolymer, the midblock portion is the polyisoprene 
portion of the molecule. 
The tackifier resin or blend, or blend of tackifier resin(s) and liquid 
plasticizer oil(s) of the novel adhesive can be any of 
solid tackifier resin(s), 
liquid tackifier resin(s), 
blend of a solid tackifier resin(s) and liquid tackifier resin(s), 
a blend of a solid tackifier resin(s) and liquid plasticizer oil(s), and 
a blend of solid tackifier resin(s), liquid tackifier resin(s), and liquid 
plasticizer oil(s). 
The blends are preferred, because they give a formulator more control over 
the rheological properties of the adhesive than does the use of a single 
tackifier resin. For example, when the proportion of elastomeric block 
copolymer is near the high end (i.e., 55-80 parts) and the CMTg is near 
the high end (i.e., within 10 Kelvin) of the aforementioned ranges, the 
novel adhesive tends to have high resistance to shear forces and to be 
low-tack or tack-free. This type of adhesive will be best suited for use 
as a self-adhering adhesive. Its low, or no, tack makes it have little or 
no adhesion to other substrates while its high resistance to shear when 
attached to itself makes it ideal for a reuseable adhesive closure system. 
On the other hand, the novel adhesive can be somewhat tacky when the 
proportion of elastomeric block copolymer is near the low end (i.e., 20-45 
parts) and the CMTg is near the high end of those ranges. These adhesives 
are generally usable as repositionable adhesive tapes, however, they will 
have a tendency to buildup adhesion over extended periods of time. These 
adhesives however will still be self-adhering and show the characteristics 
discussed above. 
The least buildup of adhesion to other substrates is realized when both the 
proportion of elastomeric block copolymer and the CMTg are relatively low. 
These adhesives are the best suited for use as a repositionable tape on 
note pads, such as is used in a Post-it.TM. pad. These tapes, however, 
will still display self adhesion properties, although generally with lower 
shear resistance. 
Overall, the lower buildup of adhesion to other substrates seems to be 
primarily related to CMTg while the tendency to build up adhesion to 
itself seems to be primarily a function of percent polymer concentration. 
However, these observations are merely generally noted trends, and 
suitable adhesives for, e.g., self-adhering tape applications or 
repositionable tapes can be found outside the most likely areas to find 
such tapes within the invention composition. 
In addition to the foregoing components, the adhesive of the invention can 
incorporate small amounts of other materials commonly used in 
pressure-sensitive adhesives, e.g. antioxidants such as hindered phenols 
and hydroquinones, heat stabilizers such as zinc carbamates, ultraviolet 
stabilizers, fillers, and pigments. Such additional materials can be 
disregarded in the CMTg calculation. 
The adhesive of the invention can be economically converted to tapes by 
being coated onto backings at high speeds without the use of solvents, or 
can be coated from solution when that is more convenient. Depending on the 
backing, the backings can be surface treated to promote adhesion of the 
adhesive thereto. The resulting tapes can be marketed in strips or in wide 
sheets and usually have flexible backings for ease of storage, handling, 
and application. For example, stripes of the novel adhesive can be coated 
onto paper which is then cut and stacked to form a tablet or note pad of 
repositionable sheets like the aforementioned POST-IT.TM. note pads. For 
such use, the adhesive is preferably somewhat tacky so that sheets of a 
note pad will adhere temporarily to paper and other substrates from which 
they can later be cleanly removed. 
For uses requiring the adhesive to be somewhat tacky, such as for a 
repositionable note pad, the CMTg can be as low as 220 Kelvin when the 
adhesive is based on styrene/isoprene or styrene/ethylene-butylene block 
copolymers which comprise up to 45% by weight of the adhesive. 
Whether or not the novel adhesive is low-tack or tack-free, pieces of tape 
bearing the adhesive have a remarkable ability to form bonds to each other 
that have excellent resistance to shear forces. In tests, even after four 
months at ordinary room temperatures, two tapes bearing the novel adhesive 
separate cleanly between their adhesive layers. The same tapes also 
separate cleanly after two hours at 37.degree. C. However, low tack 
adhesives with properties best suited for use as a repositionable adhesive 
have a tendency to block slightly at above ambient temperatures (e.g., at 
37.degree. C.). Therefore, these adhesives would not be as desirable for 
self-adhering adhesive closures used in close contact with a heated body, 
such as in a diaper closure system. 
In any event, the ability of certain inventive compositions to separate 
cleanly after 2 hours at 37.degree. C. would make these inventive 
adhesives well suited for reclosable apparel closures that are used in 
close proximity to the wearer. Examples of uses for such closure systems 
include diapers, incontinence devices, surgical gowns, hats or booties, 
clean room garments, ankle bands, wrist bands or the like. When used, as 
in reclosable apparel closures, the adhesive can be directly applied to 
the article or applied as a tape where the side which is permanently 
attached to the article can have a suitable conventional adhesive. The 
adhesive would generally be applied as patches on each side of a closure 
point, e.g., on opposing faces of at least two closure elements that mate 
to complete the closure. When the two closure elements of the article are 
brought into contact the adhesive patches will come into contact yielding 
a resealable closure. The patches can be of a size and arrangement such 
that they will contact each other over a number of overlapping positions 
of the closure elements to form an adjustable closure. 
For example, the novel adhesive can be used to provide a reclosable 
disposable diaper by applying a patch of the adhesive to the inner face of 
each of the corners at the back of a disposable diaper and also to the 
outer shell where the front of the diaper can be overlapped by the corners 
when the diaper is wrapped around the waist of a person. The face-to-face 
contact between those adhesive patches holds the diaper securely in place, 
but these patches can be easily peeled apart, either to remove or to 
refasten the diaper. 
Where a closure system is used at ambient conditions generally any adhesive 
composition of the invention can be used with suitable adjustment of the 
size, shape, and location of the adhesive patches to account for slight 
variations in the strength of the adhesive bonding strength. 
The novel adhesive also can be used to permit labels and masking tapes to 
be cleanly removed from substrates to which they may be applied. Other 
useful tape articles of the invention that have flexible backings include 
reclosable mailing envelopes, resealable bags, adhesive-backed sandpaper 
and sanding disks, and decals. The novel adhesive also can be marketed in 
a spray can from which layers can be applied for uses such as temporarily 
mounting posters or photographs. 
DETAILED DISCLOSURE 
Elastomeric block copolymers that are useful in the adhesive of the 
invention can have any of the common configurations of the block structure 
including linear diblock and triblock, radial, star, and tapered 
geometries. Useful elastomers include styrene/isoprene block copolymers 
such as "Kraton" 1107 and "Kraton" 1111, available from Shell Chemical 
Co.; "Enichem" SOL T 190, available from Enichem USA; "Quintac" 3421, 
"Quintac" 3430 and "Quintac" 3530, available from Nippon-Zeon; Finaprene 
424, available from Fina Chemical Co.; styrene/butadiene block copolymers 
such as "Kraton" 1101 and 1102; "Stereon" 840A, available from Firestone 
Synthetic Latex and Rubber Co., and "Enichem" Sol T 1205 and Sol T 161 C; 
and styrene/ethylene-butylene block copolymers such as "Kraton" 1657 and 
1650. 
Tackifier resins that are useful in the novel adhesives include those 
aliphatic hydrocarbon resins made from the polymerization of a feed stream 
consisting mainly of unsaturated species containing four to six carbon 
atoms, such as "Wingtack" 10, "Wingtack Plus", and "Wingtack" 95, 
available from the Goodyear Tire and Rubber Co., "Escorez"1310, available 
from Exxon Chemical Co., and "Hercotac" RT-95, available from Hercules, 
Inc.; rosin esters and rosin acids such as "Hercoflex" 400, "Hercoflex" 
500, "Foral" 85, "Regalite" 355, and "Permalyn" 305, all available from 
Hercules, Inc.; mixed aliphatic/aromatic liquid tackifiers such as 
"Escorez" 2520 available from Exxon Chemical Co.; and polyterpene 
tackifiers such as "Zonarez" A-25 and "Zonarez" A-100, available from 
Arizona Chemical Co. and "Piccolyte" HM-85, HM-105, and S-115 available 
from Hercules, Inc. Also useful are the general class of hydrogenated 
tackifying resins, including ECR-327, "Escorez" 5380, "Escorez" 5300, 
"Escorez"5320, and "Escorez" 5340, all available from Exxon Chemical Co.; 
"Regalrez" 1018, "Regalrez" 1065, "Regalrez" 1078, "Regalrez" 1094, and 
"Regalrez" 1126, all available from Hercules Inc.; and "Arkon" P-90, 
"Arkon" P-100, "Arkon" M-90, and "Arkon" M-100, available from Arakawa 
Chemical Co.; hydrogenated polyterpene resins such as "Nirez" K-85, 
"Nirez" K-105, and "Nirez" K-110, available from Reichhold Chemicals, 
Inc.; and hydrogenated aliphatic and aliphatic/aromatic resins such as 
ECR-142H and ECR-143H, available from Exxon Chemical Co. Preferred 
tackifying resins include the aliphatic hydrocarbon resins, the 
hydrogenated resins, and the polyterpene resins. Especially preferred are 
the aliphatic hydrocarbon resins. 
The liquid plasticizer oils suitable for use in the adhesive of the 
invention include naphthenic oils such as "Shellflex" 371, available from 
Shell Chemical Co., paraffinic oils, aromatic oils, and mineral oils such 
as "Kaydol" oil, available from Witco Chemical Corp. Preferred liquid 
plasticizers include naphthenic oil and mineral oil.

The disposable diaper shown in FIG. 1 is a conventional three layer 
composite including a liquid-permeable user-contacting topsheet 12, a 
liquid-impervious outer shell (backsheet) 14, and an absorbent layer 
therebetween (not shown). At the back 18 of the diaper are corners 20 that 
overlap the front of the diaper 22 at corners 28 when the diaper is worn 
as shown. On the topsheet side of each corner 20 is placed a patch of the 
inventive adhesive 24. On the outer shell 14 at the front 22 of the diaper 
are two patches 26 of the inventive adhesive. The patches are placed on 
the diaper such that they will come into contact when the diaper is worn 
as shown. 
The overlapping portions of the adhesive patches should provide a force to 
peel generally from 2 to 12N, preferably from 5 to 7N. To provide this 
peel force resistance and still provide for adjustability, the adhesive 
patches are placed as is shown in FIG. 1. Each patch would be preferably 
from 3 to 6 cm in length and from 1.5 to 3 cm in width. The lengthwise 
directions of the patches are preferably orthogonal to each other. This 
orientation will provide the greatest degree of adjustability for the 
preferred patches. Where the patches are so oriented and overlap over an 
entire width portion, the area of contact will be from 1.75 cm.sup.2 to 9 
cm.sup.2 for rectilinear shaped patches. Generally this degree of overlap 
provides sufficient peel resistance for use as a diaper closure system 
while avoiding excessive or wasteful use of the adhesive. 
Testing 
Some tapes bearing the adhesive of the invention were subjected to one or 
more of the following tests: 
Probe Tack Value 
This is run according to ASTM D-2979 except using a Polyken Probe Tack 
tester with a polypropylene probe at a 1 cm/second probe speed, a 1 second 
dwell time, and a 100 gram/cm.sup.2 load. 
90.degree. Peel Value 
This is run according to PSTC-5 using a polyethylene substrate to which the 
test tape was applied using a 2-kg hard rubber roller, one pass in each 
direction at 30 cm/min. An adhesive which has a 90.degree. Peel Value of 
from 2 to 8N/25 mm should be useful for making note pads of repositionable 
sheets like POST-IT.TM. note pads, because such adhesive-bearing sheets 
should adhere well to paper and other substrates while being removable 
without picking fibers, even after prolonged periods of time. When the 
90.degree. Peel Value is from 0 to 2N/25 mm, the adhesive would be most 
useful in the above-described adhesive-to-adhesive diaper closure as these 
are the least likely to adhere to ordinary packaging materials or to the 
non-adhesive surfaces of the diaper and hence will not require the use of 
a protective tape. However, protective tapes can be avoided with even 
higher peel values. For example, repositionable adhesive formulations may 
adhere to the diaper parts, however, this may be used to advantage in 
keeping the diaper folded or at worst be ignored as not affecting tape 
performance. 
180.degree. Peel Value 
This is run according to ASTM D-1000 except that the adhesive tape is 
applied to various substrates using a 2-kg hard rubber roller, one pass in 
each direction at 30 cm/min, and testing was carried out after less than 
20 minutes dwell at ordinary room temperature. The peel rate is 30 cm/min 
when the substrate is paper and 225 cm/min when the substrate is metal or 
plastic. 
Tapes are also tested after two weeks of accelerated aging at 120.degree. 
F. (49.degree. C.) and then allowed to cool to room temperature for 
testing. 
180.degree. Dynamic Shear Value 
This value was determined using ASTM Test Method D3528-76 at a crosshead 
speed of 10 inches (25 cm) per minute. 
T-Peel Value 
This value was determined using ASTM Test Method D1876-72 at a crosshead 
speed of 10 inches (25 cm) per minute. 
Self-Adhesion Peel Value 
with the adhesive layers of two pieces of the same adhesive tape 
face-to-face, a 2-kg hard rubber roller is applied, one pass in each 
direction at 30 cm/min. The resulting sandwich is tested for T-peel by 
ASTM D-1876 at 30 cm/min. 
Shear Adhesion Value 
A one-inch square (2.54 cm-square ) area of a test tape is laid with its 
adhesive layer against an embossed polyethylene substrate that is used as 
the backsheet of LUV's brand disposable diapers manufactured by Procter 
and Gamble and is about 30 .mu.m thick. To enhance the stiffness of the 
substrate, the polyethylene substrate is laminated to a pressure-sensitive 
adhesive tape, viz., Release Tape Y-9378 manufactured by 3M Co. 0n the 
side opposite the reinforcing tape, the test tape is rolled down onto the 
polyethylene substrate with a 2-kg hard rubber roller, one pass in each 
direction at 30 cm/min. The laminated substrate and the test tape are hung 
vertically in a 40.degree. C. oven for 15 minutes and a 500-gram weight is 
promptly hung from the test tape. The time for the weight to drop at 
40.degree. C. is the Shear Adhesion Value. 
The following examples, in which all parts are by weight, are given by way 
of illustration and are not intended to limit the scope of the invention 
in any way. Commercial materials used in the examples were: 
______________________________________ 
ELASTOMERIC BLOCK COPOLYMERS MTg 
"Finaprene" 424 
Styrene/isoprene block copolymer 
215K 
"Kraton" 1101 
Styrene/butadiene block copolymer 
188K 
"Kraton" 1107 
Styrene/isoprene block copolymer 
215K 
"Kraton" 1111 
Styrene/isoprene block copolymer 
215K 
"Kraton" 1657 
Styrene/ethylene-butylene block 
215K 
copolymer 
"Quintac" 3430 
Styrene/isoprene block copolymer 
215K 
SOLID TACKIFIER RESINS Tg 
"Arkon" P-90 
Hydrogenated hydrocarbon 
309K 
"Escorez" 1310 
C5 aliphatic 314K 
"Escorez" 5300 
Hydrogenated hydrocarbon 
323K 
"Foral" 85 Rosin ester 313K 
"Piccolyte" 
Styrenated terpene 327K 
HM-105 
"Regalite" 355 
Hydrogenated rosin acid 
318K 
"Regalrez" 1094 
Hydrogenated hydrocarbon 
310K 
"Wingtack" 95 
C5 aliphatic 323K 
"Wingtack Plus" 
C5 aliphatic 315K 
"Zonarez" A-100 
Alpha-pinene 328K 
LIQUID TACKIFIER RESINS 
ECR-143H Hydrogenated hydrocarbon 
247K 
"Escorez" 2520 
Aromatic/aliphatic 253K 
"Hercoflex" 500 
Rosin ester 238K 
"Wingtack" 10 
C5 aliphatic 245K 
"Zonarez" A-25 
Alpha-pinene 251K 
LIQUID PLASTICIZER OILS 
"Kaydol" Oil 
Mineral oil 199K 
"Shellflex" 371 
Naphthenic oil 209K 
ANTIOXIDANTS 
"Irganox" 1076 
Hindered Phenol (available from 
Ciba-Geigy) 
"Irganox" 1010 
Hindered Phenol 
______________________________________ 
EXAMPLES 1-18 
Eighteen adhesive compositions were prepared by dissolving in toluene the 
components of the formulations given in Table I. One part of "Irganox" 
1076 was added to each adhesive composition. Each adhesive solution was 
65% by weight of solvent. Tape samples were prepared by coating the 
adhesive solutions onto a matte-finish cast-polypropylene backing having a 
thickness of 100 .mu.m. The coating weight of the adhesive after drying at 
60.degree. C. for 5 minutes was about 3.5 mg/cm.sup.2. 
Results of testing the tapes of Examples 1-18 are reported in Table II. 
TABLE I 
__________________________________________________________________________ 
(Compositions for Examples 1-9 in Parts) 
Example 1 2 3 4 5 6 7 8 9 
__________________________________________________________________________ 
"Finaprene" 424 
60 
"Kraton" 1107 
75 50 65 40 80 
"Kraton" 1111 50 45 80 
"Escorez" 2520 
23 47 19 
"Kaydol" Oil 31 26 
"Shellflex" 371 43 7 
"Zonarez" A-25 
32 16 
"Arkon" P-90 2 3 16 
"Escorez" 1310 
8 
"Escorez" 5300 19 29 
"Wingtack Plus" 17 13 
"Zonarez" A-100 4 
Composite 235 
225 
235 235 
225 
225 
225 235 
225 
Midblock Tg 
(Kelvin) 
__________________________________________________________________________ 
(Compositions for Examples 10-18 in Parts) 
Example 10 11 12 13 14 15 16 17 18 
__________________________________________________________________________ 
"Kraton" 1101 20 50 
"Kraton" 1111 
50 70 
"Kraton" 1657 70 40 
"Quintac" 3430 75 40 60 
ECR-143H 29 58 
"Shellflex" 371 57 23 
"Wingtack" 10 20 56 24 
"Zonarez" A-25 
48 16 
"Arkon" P-90 1 2 
"Piccolyte" HM-105 23 27 
"Regalrez" 1094 5 4 16 
"Zonarez" A-100 
2 14 
Composite 235 
235 
225 235 
235 
225 225 
225 
235 
Midblock Tg 
(Kevlin) 
__________________________________________________________________________ 
TABLE II 
______________________________________ 
Probe 90 Shear Self-Adhesion 
Tack Peel Value 
Adhesion Value 
Peel Value 
Example 
(N) (N/25 mm) (minutes) (N/25 mm) 
______________________________________ 
1 4.2 1.4 2 2.2 
2 0.9 0.3 &lt;1 2.1 
3 4.5 1.1 2 2.2 
4 3.3 1.4 1 1.6 
5 3.2 0.4 3 1.6 
6 1.6 1.0 1 1.0 
7 2.2 0.7 3 0.5 
8 6.5 2.0 26 0.9 
9 0.9 0.3 16 1.2 
10 3.5 2.0 2 0.9 
11 3.0 1.5 25 1.6 
12 1.1 0.4 1 0.8 
13 5.9 2.7 6 2.5 
14 3.9 1.9 11 2.7 
15 2.9 0.2 &lt;1 0.2 
16 2.6 0.8 &lt;1 0.6 
17 0.2 0.1 &lt;1 2.3 
18 2.9 0.4 11 3.4 
______________________________________ 
EXAMPLES 19-22 
A series of adhesive compositions was made as reported in Table III, and 
each was dissolved in toluene to a total solids concentration of 25%, with 
0.5% of "Irganox" 1010 added to stabilize the adhesive against aging. Each 
composition was then coated onto a 25 .mu.m thick biaxially oriented 
poly(ethylene terephthalate) backing and dried to a dry coating weight of 
about 1.0 mg/cm.sup.2. The blocks in the star block copolymer used in 
Examples 20-22 have a linear configuration, with the isoprene chain capped 
on each end with styrene chains and were prepared in accordance with the 
procedure outlined in U.S. Pat. No. 4,780,367, the substance of which is 
incorporated herein by reference, using a divinylbenzene catalyst to yield 
a polymer with 16.8% styrene and the remainder predominately isoprene. 
Results of testing each of Examples 19-22 for 180.degree. Peel Value are 
reported in Table IV. 
TABLE III 
______________________________________ 
(Compositions for Examples 19-22) 
Material 19 20 21 22 
______________________________________ 
"Kraton" 1107 
80 17 
Star block polymer 35 20 25.5 
of styrene/isoprene 
"Wingtack Plus" 
17.4 0.3 1.7 0.3 
"Wingtack" 10 
2.6 64.7 78.3 57.2 
CMTg 230 235 240 232.5 
______________________________________ 
TABLE IV 
______________________________________ 
(180.degree. Peel Value in 02/g) 
Substrate 19 20 21 22 
______________________________________ 
Paper 1.7 3.2 5.0 2.4 
After aging 4.1 8.9 6.6 7.0 
Stainless Steel 
16 11 25 17 
After aging 31 25 35 28 
BOPP 19 13 24 20 
After aging 18 19 26 20 
PET 28 18 23 22 
After aging 28 29 35 27 
______________________________________ 
Paper = ordinary bond copypaper 
BOPP = biaxially oriented polypropylene 
PET = biaxially oriented poly(ethylene terephthalate) 
The data reported in Table IV show that each of the adhesives of Examples 
19-22 has low adhesion to paper and other substrates and has low adhesion 
build-up with time evidenced by low adhesion after accelerated aging for 
two weeks at 49.degree. C. This demonstrates that the adhesive of any of 
Examples 19-22 should be a suitable substitute, in repositionable note 
pads, for the adhesive of the above-cited Silver patent, even though these 
are not preferred examples of such substitute adhesives. 
EXAMPLE 23 
A handspread of 50% solution in toluene of 70 parts of "Kraton" 1657 and 30 
parts of "Res" D-2084 was pulled onto biaxially oriented poly(ethylene 
terephthalate) film having a thickness of 2.5 .mu.m. The dried coating 
weight was about 24 g/m.sup.2. This adhesive had: 
CMTg=238 Kelvin 
180.degree. Dynamic Shear Value to itself=588N/cm.sup.2 
T-Peel Value=6.5N/25 mm 
Comparative Examples A-G 
A series of tapes were made in the same way as the tapes of Examples 1-18 
except using adhesive compositions indicated in Table V. Some of the 
adhesive compositions were as taught in the prior art as follows: 
______________________________________ 
Comparative Example 
Adhesive as Taught in 
______________________________________ 
F Sample 10 of Example III 
in U.S. Pat. No. 3,954,692 (Downey) 
G Example 4 of U.S. Pat. No. 3,932,328 
(Korpman) 
______________________________________ 
TABLE V 
______________________________________ 
(Compositions in Parts) 
Comparative 
Example A B C D E F G 
______________________________________ 
"Finaprene" 424 
40 
"Kraton" 1107 50 100 100 
"Quintac" 3430 40 30 40 
"Wingtack" 10 26 11 40 
"Zonarez" A-25 
22 
"Kaydol" Oil 6 20 
"Shellflex" 371 8 
"Wingtack" 95 100 100 
"Escorez" 1310 
38 
"Regalite" 355 54 
"Regalrez" 1094 44 49 
"Wingtack Plus" 42 
Composite 258 250 262 260 260 254 254 
Midblock Tg 
(Kelvin) 
______________________________________ 
Testing of comparative example A-G is reported in Table VI. 
TABLE VI 
______________________________________ 
Probe 90.degree. 
Shear Self-Adhesion 
Tack Peel Value 
Adhesion Value 
Peel Value 
Example 
(N) (g/25 mm) (minutes) (N/25 mm) 
______________________________________ 
A 13 7.3 &gt;1000 15 
B 10 4.6 &gt;1000 12 
C 10 13.6 &gt;1000 12 
D 9 9.3 &gt;1000 18 
E 12 8.0 &gt;1000 17 
F 11 4.9 &gt;1000 18 
G 10 7.8 &gt;1000 16 
______________________________________ 
As indicated in Tables II and VI, comparative Examples A through G exhibit 
tack, peel, shear and self-adhesion values that are substantially greater 
than Example 1 through 18 and are typical of conventional 
pressure-sensitive adhesives that are based on elastomeric block 
copolymers. 
Other embodiments of the invention will be apparent to those skilled in the 
art from a consideration of this specification or practice of the 
invention disclosed herein. It is intended that the specification and 
examples be considered as exemplary only, with the true scope and spirit 
of the invention being .indicated by the following claims.