Dissimilar arm asymmetric radial or star block copolymers for adhesives and sealants

Radial or star asymmetric block copolymer of the following formulae and improved adhesive and sealant compositions containing them EQU (I) (A--HD).sub.x --Y--(UD).sub.z or (II) (UD--A--HD).sub.x --Y or (III) ((UD).sub.y --A--HD).sub.x --Y--(UD).sub.z wherein A is a vinyl aromatic hydrocarbon block having a molecular weight of from 4000 to 20,000, HD is a hydrogenated conjugated diene block having a molecular weight of from 10,000 to 100,000, Y is a multifunctional coupling agent, UD is an unhydrogenated conjugated diene block having a molecular weight of from 1000 to 80,000, x is an integer from 2 to 20, y is 0 or 1, z is an integer from 1 to 10, and x+z ranges from 3 to 30.

BACKGROUND OF THE INVENTION 
This invention is directed to adhesive and sealant compositions which 
contain dissimilar arm asymmetric radial block copolymers. More 
particularly, the invention is related to such compositions containing 
asymmetric block copolymers which have both hydrogenated and 
unhydrogenated sets of arms. 
Block copolymers have been employed in adhesive compositions for many 
years, primarily because of their high cohesive strengths and their 
ability to crosslink without a chemical vulcanization step. Block 
copolymers such as those described in U.S. Pat. No. 3,239,478 are either 
linear or radial or star styrene-butadiene or styrene-isoprene block 
copolymers. The high cohesive strength of these polymers is often a 
detrimental quality in certain applications. In the past, cohesive 
strength was reduced by adding a styrene-isoprene diblock copolymer to the 
primary block copolymer to lower the cohesive strength and give less 
elasticity and better conformability. U.S. Pat. No. 4,391,949 suggested 
another approach whereby a star-shaped asymmetric block copolymer having 
styrene-diene and diene homopolymer arms was used. 
These conventional block copolymers when used in adhesives tend to degrade 
in processing and/or over time because they are unsaturated in the main 
rubber chain. These unsaturation sites are reactive sites which are 
vulnerable to attack, such as by free radicals created by oxidation, 
ultraviolet light or mechanical action. As a result, the polymer chain may 
be severed by chain scission, reducing the molecular weight and those 
properties which are sensitive to molecular weight. Alternatively, the 
unsaturation sites may be subjected to grafting and crosslinking reactions 
which raise the molecular weight and undesirably stiffen the polymer 
making it unprocessable or ineffective as an adhesive. Hydrogenating the 
conventional unsaturated base polymers creates a nonpolar polymer which, 
although more stable, is difficult to tackify with resin additives and 
which is therefore inferior to conventional polymers in some applications, 
including pressure sensitive adhesives. 
The present invention offers a solution to some of these problems without 
sacrificing the adhesive qualities of unsaturated block copolymers. It 
does so by providing a polymer which has both unsaturated and saturated 
arms. 
SUMMARY OF THE INVENTION 
The present invention provides improved adhesive and sealant compositions 
which comprise a radial or star asymmetric block copolymer of the formulae 
EQU (I) (A--HD).sub.x --Y--(UD).sub.z or (II) (UD--A--HD).sub.x --Y or (III) 
((UD).sub.y --A--HD).sub.x --Y--(UD).sub.z 
wherein A is a vinyl aromatic hydrocarbon block having a molecular weight 
of from 4000 to 20,000, HD is a hydrogenated conjugated diene block having 
a molecular weight of from 10,000 to 100,000, Y is a multifunctional 
coupling agent, UD is an unhydrogenated conjugated diene block having a 
molecular weight of from 1000 to 80,000, x is an integer from 2 to 20, 
preferably 2 to 4, y is 0 or 1, z is an integer from 1 to 10, preferably 1 
to 4, and x+z ranges from 3 to 30, preferably 3 to 6; and from 20 to 400 
parts per 100 parts of copolymer of a tackifying resin. These compositions 
may also contain resins which extend the diene phase, resins which 
reinforce and/or extend the vinyl aromatic phase, polyolefins, fillers, 
wax, stabilizers and reactive components designed to crosslink the 
polymers and/or resins. 
DETAILED DESCRIPTION OF THE INVENTION 
The primary novel component of the adhesive and sealant compositions of the 
present invention is the above-described block copolymer which has both 
saturated and unsaturated arms. The styrene-hydrogenated diene arms 
provide the primary load bearing capability of the adhesive and sealant 
compositions. It is important that these arms be hydrogenated so that the 
structural integrity of the polymer is preserved even if outside forces 
cause degradation of the unsaturated side chains. The unsaturated diene 
homopolymer arms are important in the composition to give the composition 
sufficient tack properties and/or the ability to be tackified to make 
effective compositions, such as pressure sensitive adhesive compositions. 
The A blocks are polymer blocks of a vinyl aromatic hydrocarbon. 
Preferably, the vinyl aromatic hydrocarbon is styrene. Other useful vinyl 
aromatic hydrocarbons include alphamethyl styrene, various 
alkyl-substituted styrenes, alkoxy-substituted styrenes, vinyl 
naphthalene, vinyl toluene and the like. The HD and UD blocks are polymer 
blocks of conjugated dienes. The preferred diene for the HD blocks is 
butadiene. Isoprene is preferred for the UD blocks. Other dienes may also 
be used, including piperylene, methylpentadiene, phenylbutadiene, 
3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadiene and the like, 
preferably those conjugated dienes containing 4 to 8 carbon atoms. It is 
preferred that the conjugated diene employed in the HD block differ from 
that employed in the UD block, especially in respect to ease of 
hydrogenation. 
The diene in the HD block should preferably hydrogenate faster and more 
completely than the diene in the UD block. The amount of hydrogenation in 
the unsaturated (UD) blocks after the reaction should be such that at 
least 50 percent, preferably at least 75 percent, most preferably at least 
90 percent, of the original unsaturated diene remain unreacted. 
The A--HD arms or blocks may be hydrogenated as generally described in the 
prior art, preferably so as to reduce at least about 90 percent of any 
olefinic double bonds in the polymer chains. Suitably at least 50 percent, 
preferably at least 70 percent, and more preferably at least 90 percent, 
most preferably at least 95 percent of the original olefinic unsaturation 
is hydrogenated. 
The dienes used in this invention preferably should be those which are 
largely amorphous at use temperatures (usually 10.degree. C. to 40.degree. 
C.) and do not contain excess crystallinity which would interfere with 
flexibility. For butadiene, e.g., the percent of 1,2 addition should 
preferably be 30 percent to 65 percent to prevent excessive crystallinity 
after hydrogenation to ethylene-butylene (EB) rubber. Below 30 percent 
crystallinity is too high, giving a stiff polymer which is unsuitable for 
pressure sensitive adhesives. Above 65 percent the Tg (glass transition 
temperature) of the polymer is too high, making it difficult to formulate 
an acceptable pressure sensitive adhesive. 
The preferred method for making the block copolymers of the present 
invention is basically described in European Patent Application 0,314,256. 
Therein is disclosed a two-step process for producing asymmetric radial 
polymers which avoids the problem of the production of the unwanted 
homopolydiene polymer. The process involves separately polymerizing the 
monomers to create separately the two different types of arms. Then one of 
the polymeric arms is coupled to the coupling agent and when that coupling 
reaction is complete, the second set of polymer arms is coupled to the 
coupling agent. This ensures that there will be very little homopolydiene 
in the final polymer. In the present invention, for example, isoprene arms 
would be anionically polymerized, and coupled via the coupling agent. 
Subsequently or in parallel, styrene-butadiene (SB) arms would be 
anionically polymerized and at least 2 arms then coupled to the isoprene 
arms via the coupling agent. These unhydrogenated precursors are useful as 
adhesives and sealants on their own but they suffer the stability problems 
common to polymers with a high degree of unsaturation (for example, 
(SB).sub.2 --Y--I.sub.2). Subsequently, the coupled polymer is 
hydrogenated under conditions that preferably hydrogenate the diene of the 
A--HD arm (or block) only, leaving the diene of the UD arm (or block) 
essentially unsaturated. 
In general, the method described is used to prepare asymmetric radial or 
star polymers with any polymer containing a reactive end group which will 
react with one or more functional groups contained in the selected 
coupling agent. The method is particularly suitable for the preparation of 
asymmetric radial polymers from so-called "living" polymers containing a 
single terminal metal ion. As is well known in the prior art, "living" 
polymers are polymers containing at least one active group such as a metal 
atom bonded directly to a carbon atom. "Living" polymers are readily 
prepared via anionic polymerization. Since the present invention is 
particularly well suited to the preparation of asymmetric radial polymers 
using "living" polymers to form the arms thereof, the invention will be 
described by reference to such polymers. It will, however, be appreciated 
that the invention would be equally useful with polymers having different 
reactive groups so long as the selected coupling agent contains functional 
groups which are reactive with the reactive site contained in the polymer. 
Living polymers containing a single terminal group are, of course, well 
known in the prior art. Methods for preparing such polymers are taught, 
for example, in U.S. Pat. Nos. 3,150,209; 3,496,154; 3,498,960; 4,145,298 
and 4,238,202. Methods for preparing block copolymers such as those 
preferred for use in the method of the present invention are also taught, 
for example, in U.S. Pat. Nos. 3,231,635; 3,265,765 and 3,322,856. These 
patents are herein incorporated by reference. When the polymer product is 
a random or tapered copolymer, the monomers are, generally, added at the 
same time, although the faster reacting monomer may be added slowly in 
some cases, while, when the product is a block copolymer, the monomer used 
to form the separate blocks are added sequentially. 
In general, the polymers useful as arms in the asymmetric radial polymers 
of this invention may be prepared by contacting the monomer or monomers 
with an organoalkali metal compound in a suitable solvent at a temperature 
within the range from -150.degree. C. to 300.degree. C., preferably at a 
temperature within the range from 0.degree. C. to 100.degree. C. 
Particularly effective polymerization initiators are organolithium 
compounds having the general formula: 
EQU RLi 
wherein R is an aliphatic, cycloaliphatic, alkyl-substituted 
cycloaliphatic, aromatic or alkyl-substituted aromatic hydrocarbon radical 
having from 1 to 20 carbon atoms. 
In general, the living polymers used as arms in the asymmetric radial 
polymer will be contacted with the coupling agent at a temperature within 
the range from 0.degree. C. to 100.degree. C. at a pressure within the 
range from 0 bar to 7 bar and the contacting will be maintained until 
reaction between the arms and the coupling agent is complete or at least 
substantially completed, generally for a period of time within the range 
from 1 to 180 minutes. 
In general, the polymers useful as arms in the asymmetric radial polymers 
of this invention will be in solution when contacted with the coupling 
agent. Suitable solvents include those useful in the solution 
polymerization of the polymer and include aliphatic, cycloaliphatic, 
alkyl-substituted cycloaliphatic, aromatic and alkyl-substituted aromatic 
hydrocarbons, ethers and mixtures thereof. Suitable solvents, then, 
include aliphatic hydrocarbons such as butane, pentane, hexane, heptane 
and the like, cycloaliphatic hydrocarbons such as cyclohexane, 
cycloheptane and the like, alkyl-substituted cycloaliphatic hydrocarbons 
such as methylcyclohexane, methylcycloheptane and the like, aromatic 
hydrocarbons such as benzene and the alkyl-substituted aromatic 
hydrocarbons such as toluene, xylene and the like and ethers such as 
tetrahydrofuran, diethylether, di-n-butyl ether and the like. Since the 
polymers useful in making the asymmetric radial polymers of this invention 
will contain a single terminal reactive group, the polymers used in 
preparation of the asymmetric radial polymers will be retained in solution 
after preparation without deactivating the reactive (living) site. In 
general, the coupling agents may be added to a solution of the polymer or 
a solution of the polymer may be added to the coupling agent. 
Any of the coupling agents known in the prior art to be useful in forming a 
radial polymer by contacting the same with a living polymer may be used in 
both the method of this invention and the asymmetric radial polymers of 
this invention. Suitable coupling agents will contain three or more 
functional groups which will react with the living polymer at the 
metal-carbon bond. While the method of the present invention will improve 
the relative distribution of different arms in an asymmetric radial 
polymer having any number of arms, the method is very effective when the 
coupling agent contains from three to about twenty functional groups 
reactive with the metal-carbon bond of the "living" polymer. Suitable 
coupling agents, then include SIX.sub.4, RSiX.sub.3, HSiX.sub.3, X.sub.3 
Si--SiX.sub.3, RX.sub.2 Si--(CH.sub.2).sub.x --SiX.sub.2 R, RX.sub.2 
Si(CH.sub.2).sub.x --SiX.sub.2 --(CH.sub.2).sub.x --SiX.sub.2 R, X.sub.3 
Si--(CH.sub.2).sub.x --SiX.sub.3, R--C(SiX.sub.3).sub.3, R--C(CH.sub.2 
SiX.sub.3).sub.3, C(CH.sub.2 SiX.sub.3).sub.4 and the like, particularly 
those containing from three to about six functional groups. In the 
foregoing formulae: each X may, independently, be fluorine, chlorine, 
bromine, iodine, alkoxide radicals, carboxylate radicals, hydride and the 
like; R is a hydrocarbyl radical having from 1 to about 10 carbon atoms, 
preferably from 1 to about 6 carbon atoms; and x is a whole number from 1 
to about 6. Particularly useful coupling agents include the silicon 
tetrahalides such as silicon tetrafluoride, silicon tetrachloride, silicon 
tetrabromide and the like, and bis(trihalo)silanes such as 
bis(trihalo)silylethane and hexahalodisilane where the halogen may be 
fluorine, chlorine, bromine, or iodine. 
The coupling process per se is described in detail in U.S. Pat. No. 
4,096,203 which is herein incorporated by reference. Specific 
multifunctional coupling agents useful herein are described in that patent 
but there are other coupling agents which may also be useful herein. 
Star polymers are made by coupling polymer arms using a polyfunctional 
coupling agent or coupling monomer. A preferred coupling agent is a 
polyalkenyl aromatic coupling agent such as those described in U.S. Pat. 
Nos. 4,010,226, 4,391,949 and 4,444,953, which are herein incorporated by 
reference. U.S. Pat. No. 5,104,921, which is also herein incorporated by 
reference, contains a complete description of such polyalkenyl aromatic 
compounds at columns 12 and 13. Divinyl aromatic hydrocarbons containing 
up to 26 carbon atoms per molecule are preferred and particularly divinyl 
benzene in either its meta, or para isomer and commercial divinyl benzene 
which is a mixture of said isomers is also quite satisfactory. The 
coupling agent is preferably added to the living polymer after the 
polymerization is substantially complete. The amount of coupling agent 
varies between wide limits but preferably at least one equivalent is used 
per equivalent of unsaturated living polymer to be coupled. The coupling 
reaction is generally carried out in the same solvent as for the 
polymerization reaction. The temperature varies between wide limits, for 
example, from 25.degree. C. to 95.degree. C. 
The hydrogenation of these copolymer arms may be carded out by a variety of 
well established processes including hydrogenation in the presence of such 
catalysts as Raney Nickel, noble metals such as platinum, palladium and 
the like and soluble transition metal catalysts. Suitable hydrogenation 
processes which can be used are ones wherein the diene-containing polymer 
or copolymer is dissolved in an inert hydrocarbon diluent such as 
cyclohexane and hydrogenated by reaction with hydrogen in the present of a 
soluble hydrogenation catalysts. Such processes are disclosed in U.S. Pat. 
Nos. 3,113,986, 4,226,952 and Re. 27,145, the disclosures of which are 
herein incorporated by reference. The polymers are hydrogenated in such a 
manner as to produce hydrogenated polymers having a residual unsaturation 
content in the polydiene block of less than about 20 percent, and 
preferably as close to 0 percent as possible, of their original 
unsaturation content prior to hydrogenation. A titanium catalyst such as 
disclosed in U.S. Pat. No. 5,039,755, which is herein incorporated by 
reference, may also be used in the hydrogenation process. 
In a preferred aspect of the invention, the asymmetric/dissimilar arm 
structure affords the possibility of augmenting the tack of saturated 
polymers by incorporation of freely rotating rubber chain ends in the 
molecule, which are more readily tackified by resin additives than chains 
which are terminated by hard (polystyrene) blocks. An example would be a 6 
arm polymer, 4 arms of which are polyisoprene and 2 of which are 
poly(styrene-ethylene/butylene). The poly(styrene-ethylene/butylene) is 
hydrogenated poly(styrene-butadiene). This polymer is an example of a 
preferred radial polymer within the scope of formula (I) described above 
wherein A is styrene, HD is ethylene/butylene (EB), x is 2, z is 4, Y is a 
hexafunctional coupling agent, and UD is polyisoprene. The freely rotating 
homopolymer chain ends are readily tackified, while the copolymer arms 
provide load-bearing. 
An especially preferred embodiment of the invention is (I--S--EB).sub.x 
--Y, where I is a polyisoprene block, S is a polystyrene block, EB is a 
poly(ethylene/butylene) rubber block, and x and Y have the meanings 
described previously. In this embodiment, hydrogenation of the 
polybutadiene block to form the poly(ethylene/butylene) block is carried 
out under conditions that are selective for polybutadiene reaction and 
essentially exclude hydrogenation of the polyisoprene block. The 
unsaturated polyisoprene block is especially effective for imparting tack 
and peel strength to adhesive compositions. 
The present invention also contemplates asymmetric/dissimilar arm structure 
radial and star polymers of the type described herein which are entirely 
saturated. These polymers afford the possibility of augmenting the tack of 
saturated polymers by incorporation of freely rotating rubber chain ends, 
albeit saturated chain ends, in the molecule which are more readily 
tackified by resin additives than chains which are terminated by hard 
(polystyrene) blocks. An example would be a 4 arm polymer, 2 arms of which 
are hydrogenated polyisoprene and 2 arms of which are hydrogenated 
poly(styrene-butadiene). The freely rotating saturated homopolymer chain 
ends are more readily tackified while the saturated copolymer arms provide 
load-bearing. 
The polymers of the present invention generally will have an A block 
content (polystyrene content if A is styrene) of from 4 to 35 percent, 
preferably from 12 to 25 percent. This range provides the formulation 
latitude to achieve acceptable tack and shear properties demanded by the 
particular application. The polymers of the present invention preferably 
have a molecular weight of from 35,000 to 300,000. The A blocks have a 
molecular weight of from 4000 to 20,000. A blocks less than 4000 do not 
form domains of pure A and thus are not load-bearing. A blocks greater 
than 20,000 impart excess stiffness, thereby preventing pressure 
sensitivity in adhesives. The HD blocks should have a molecular weight of 
from 10,000 to 100,000. HD blocks less than 10,000 provide a weak polymer 
with poor cohesive strength and low shear properties. HD blocks greater 
than 100,000 make the rubber and adhesive compositions difficult to 
process. The UD blocks should have a molecular weight of from 1000 to 
80,000. UD blocks less than 1000 do not express tack and peel strength 
improvement in adhesives because they are not long enough to interact with 
substrate surfaces. UD blocks greater than 80,000 soften the adhesive 
composition excessively, reducing cohesive strength and holding power. 
Molecular weights are conveniently measured by Gel Permeation 
Chromatography (GPC), where the GPC system has been appropriately 
calibrated. Polymers of known molecular weight are used to calibrate and 
these must be of the same molecular structure and chemical composition as 
the unknown block polymers that are measured. Anionically polymerized 
linear block polymers are close to monodisperse and it is both convenient 
and adequately descriptive to report the "peak" molecular weight of the 
narrow molecular weight distribution observed. The "peak" molecular weight 
is very nearly the same as the weight average molecular weight of the 
block polymer. For block polymers that are more polydisperse, a weight 
average molecular weight should be measured by light scattering or 
calculated from GPC data. Measurement of the true molecular weight of the 
final coupled radial or star polymer is not as straightforward or as easy 
to make using GPC. This is because the radial or star shaped molecules do 
not separate and elute through the packed GPC columns in the same manner 
as do the linear polymers used for the calibration, and, hence, the time 
of arrival at a UV or refractive index detector is not a good indicator of 
the molecular weight. A good method to use for a radial or star polymer is 
to measure the weight average molecular weight by light scattering 
techniques. The sample is dissolved in a suitable solvent at a 
concentration less than 1.0 gram of sample per 100 milliliters of solvent 
and filtered using a syringe and porous membrane filters of less than 0.5 
microns pore size directly into the light scattering cell. The light 
scattering measurements are performed as a function of scattering angle 
and of polymer concentration using standard procedures. The differential 
refractive index (DRI) of the sample is measured at the same wavelength 
and in the same solvent used for the light scattering. The following 
references are herein incorporated by reference: 
1. Modem Size-Exclusion Liquid Chromatography, W. W. Yau, J. J. Kirkland, 
D. D. Bly, John Wiley & Sons, New York, N.Y., 1979. 
2. Light Scattering from Polymer Solution, M. B. Huglin, ed., Academic 
Press, New York, N.Y., 1972. 
3. W. Kaye and A. J. Havlik, Applied Optics, 12, 541 (1973). 
4. M. L. McConnell, American Laboratory, 63, May, 1978. 
The saturated and/or unsaturated arms of the copolymers of the present 
invention may be functionalized, such as with polar groups which increase 
adhesion to many types of surfaces, especially high energy surfaces. For 
example, the unsaturated arms may be epoxidized or carboxylated. Saturated 
arms may, for example, be maleated or silanated. Depending upon the type 
of functional group added, crosslinking may be accomplished through these 
groups. Specific groups for this purpose include acids, such as carboxylic 
acids, anhydrides, such as carboxylic acid anhydrides, epoxidizing agents, 
acrylates, vinylalkoxysilanes and the like. 
The polymers, functionalized or unfunctionalized, of this invention may be 
cured by ultraviolet or electron beam radiation, but radiation curing 
utilizing a wide variety of electromagnetic wavelength is feasible. Either 
ionizing radiation such as alpha, beta, gamma, X-rays and high energy 
electrons or non-ionizing radiation such as ultraviolet, visible, 
infrared, microwave and radio frequency may be used. 
The most common source of alpha, beta and gamma radiation are radioactive 
nuclei. An ionizing radiation source with commercial polymer crosslinking 
application is gamma radiation that is produced from either cobalt-60 or 
cesium-137 radioactive nuclei. X-rays can be produced through 
deacceleration of high speed electrons through the electric field of an 
atomic nucleus. 
High voltage electron accelerators are preferred over gamma radiation and 
certain types of X-ray processing equipment. High energy electrons 
produced by machine acceleration, as opposed to radioisotopes, can be 
applied easily to industrial processes for the following reasons: easy 
on-off switching capability; less shielding is required than with gamma 
radiation; accelerator beams are directional and less penetrating than 
gamma or X-rays; and electron radiation provides high dose rates, i.e. 
maximum penetration per unit density of material, and is well suited for 
on-line, high speed processing applications. Commercially available high 
or low energy electron-processing equipment are the Dynamitron.RTM. 
device, dynacote, insulating-core transformer, linear accelerator, Van de 
Graaff accelerator, pelletron, laddertron and linear cathode. 
Manufacturers of high voltage electron-accelerator equipment are High 
Voltage Engineering Corporation, Burlington, Mass. and Radiation Dynamics, 
Inc., Westbury, N.Y. Manufacturers of low energy electron beam generating 
equipment include American International Technologies, Inc., of Torrance, 
Calif.; RPC Industries of Hayward, Calif.; and Energy Sciences of 
Wilmington, Mass. 
Ultraviolet light sources may be based on the mercury-vapor arc. Mercury is 
enclosed in a quartz tube and a potential is applied to electrodes at 
either end of the tube. The electrodes can be of mercury, iron, tungsten 
or other metals. The pressure in the mercury-vapor lamp may be less than 1 
atm to more than 10 atm. As the mercury pressure and lamp operating 
temperatures are increased, the radiation becomes more intense and the 
width of the emission lines increases. Other UV light sources include 
electrodeless lamps, Xenon lamps, pulsed Xenon lamps, Argon ion lasers and 
Excimer lasers. 
Visible light sources can be obtained from high pressure mercury arcs by 
addition of rare gases or metal halides, which increase the number of 
emission lines in the 350-600 nm region of the spectrum. Fluorescent 
lamps, tungsten halide lamps and visible lasers may also be utilized. 
The presence of water in the polymer composition during the radiation 
crosslinking is very undesirable due to the tendency of water to terminate 
the crosslinking. The radiation curing is therefore generally more 
effective if the polymeric composition is at a temperature near or above 
the boiling point of water at the time of the radiation curing. 
The amount of radiation necessary for high gel formation varies with the 
thickness of the polymeric mass being irradiated, the amount of 
unsaturation or, functionality, the extent to which the unsaturation or 
functionality is concentrated in specific regions within the polymeric 
mass and the type of radiation utilized. When electron beam radiation is 
utilized, radiation doses of about 0.1 Mrads to about 16 Mrads are 
acceptable and from about 0.1 Mrads to about 5 Mrads are preferred because 
of equipment cost and possible damage to substrate material. 
When using non-ionizing radiation it is necessary to employ a 
photoinitiator to initiate the crosslinking reaction. Useful 
photoinitiators include diaryliodonium, alkoxy-substituted diaryliodonium, 
triarylsulfonium, dialkylphenacylsulfonium, and 
dialkyl-4-hydroxyphenylsulfonium salts. The anions in these salts 
generally possess low nucleophilic character and include SbF.sub.6 --, 
BF.sub.4 --, PF.sub.6 -- and AsF.sub.6 --. Specific examples include 
(4-octyloxyphenyl)-phenyl-iodonium hexafluoroantimonate, UVI-6990 (from 
Union Carbide), and FX-512 (3M Company). Bis(dodecylphenyl)iodonium 
hexafluoroantimonate, UV 9310C (GE), and, UVI-6974 (Union Carbide), are 
especially effective. The onium salts can be used alone or in conjunction 
with a photosensitizer to respond to long wave length UV and visible 
light. Examples of photosensitizers include thioxanthone, anthracene, 
perylene, phenothiazione, 1,2-benzathracene coronene, pyrene and 
tetracene. The photoinitiator and photosensitizer are chosen to be 
compatible with the polymer being crosslinked and the light source 
available. 
Radiation induced cationic curing may also be done in combination with free 
radical curing. Free radical curing can be further enhanced by the 
addition of additional free radical photoinitiators and photosensitizers 
for them. 
Reactive (radiation curable) diluents that can be added to the polymer 
include alcohols, vinyl ethers, epoxides, acrylate and methacrylate 
monomers, oligomers and polymers. They may also be blended with other 
diene-based polymers. Examples include bis(2,3-epoxy cyclopentyl)ether 
vinyl cyclohexene dioxide, limonene dioxide, epoxidized soya and linseed 
oils and fatty acids, vernonia oil, and UVI 6110 (Union Carbide). 
The polymers may also be cured without the use of radiation by addition of 
a cationic initiator. Suitable initiators include the halides of tin, 
aluminum, zinc, boron, silicon, iron, titanium, magnesium and antimony, 
and the fluoroborates of many of these metals. BF.sub.3 complexes such as 
BF.sub.3 -ether and BF.sub.3 -amine are included. Also useful are strong 
Bronsted acids such as trifluoromethanesulfonic acid (triflic acid) and 
the salts of triflic acid such as FC-520 (3M Company). The cationic 
initiator is chosen to be compatible with the polymer being crosslinked, 
the method of application and cure temperature. The polymers may also be 
crosslinked by the addition of multifunctional carboxylic acids and acid 
anhydrides and in general by the curing methods described in U.S. Pat. No. 
3,970,608, which is incorporated by reference. Radiation crosslinking is 
preferred for adhesives because reactive ingredients do not come in 
contact with warm adhesives. 
The materials of the present invention including in many cases crosslinked 
versions are useful in adhesives (including pressure sensitive adhesives, 
contact adhesives, laminating adhesives and assembly adhesives, labels, 
packaging adhesives, weatherable tapes), sealants, printing plates, oil 
gels, and maskants. Crosslinked forms of the invention are especially 
useful in applications requiring resistance to elevated temperatures. 
However, it may be necessary for a formulator to combine a variety of 
ingredients together with the polymers of the present invention in order 
to obtain products having the proper combination of properties (such as 
adhesion, cohesion, durability, low cost, etc.) for particular 
applications. Thus, a suitable formulation might contain only the polymers 
of the present invention and, e.g., a curing agent. However, in most 
adhesive and sealant applications, suitable formulations would also 
contain various combinations of resins, plasticizers, fillers, stabilizers 
and other ingredients such as asphalt. The following are some typical 
examples of formulations for sealants. 
In adhesives and sealant applications, it is common practice to add an 
adhesion promoting or tackifying resin that is compatible with the 
polymer, generally from 20 to 400 parts per hundred parts of polymer by 
weight. A common tackifying resin is a diene-olefin copolymer of 
piperylene and 2-methyl-2-butene having a softening point of about 
95.degree. C. This resin is available commercially under the tradename 
Wingtack.RTM. 95 and is prepared by the cationic polymerization of 60% 
piperlene, 10% isoprene, 5% cyclo-pentadiene, 15% 2-methyl-2-butene and 
about 10% dimer, as taught in U.S. Pat. No. 3,577,398. Other tackifying 
resins may be employed wherein the resinous copolymer comprises 20-80 
weight percent of piperylene and 80-20 weight percent of 
2-methyl-2-butene. The resins normally have ring and ball softening points 
as determined by ASTM method E28 between about 80.degree. C. and 
115.degree. C. 
Aromatic resins may also be employed as tackifying agents, provided that 
they are compatible with the particular polymer used in the formulation. 
Normally, these resins should also have ring and ball softening points 
between about 80.degree. C. and 115.degree. C. although mixtures of 
aromatic resins having high and low softening points may also be used. 
Useful resins include coumarone-indene resins, polystyrene resins, vinyl 
toluene-alpha methylstyrene copolymers and polyindene resins. 
Other adhesion promoting resins which are also useful in the compositions 
of this invention include hydrogenated rosins, esters of rosins, 
polyterpenes, terpenephenol resins and polymerized mixed olefins, lower 
softening point resins and liquid resins. An example of a liquid resin is 
Adtac.RTM. LV resin from Hercules. To obtain good thermooxidative and 
color stability, it is preferred that the tackifying resin be a saturated 
resin, e.g., a hydrogenated dicyclopentadiene resin such as Escorez.RTM. 
5000 series resin made by Exxon or a hydrogenated polystyrene or 
polyalphamethylstyrene resin such as Regalrez.RTM. resin made by Hercules. 
Softening points of solid resins may be from about 40.degree. C. to about 
120.degree. C. Liquid resins, i.e., softening points less than room 
temperature, may be used as well as combinations of solid and liquid 
resins. The amount of adhesion promoting resin employed varies from 0 to 
400 parts by weight per hundred parts rubber (phr), preferably between 20 
to 350 phr, most preferably 20 to 150 phr. The selection of the particular 
tackifying agent is, in large part, dependent upon the specific polymer 
employed in the respective adhesive composition. 
A composition of the instant invention may contain plasticizers, such as 
rubber extending plasticizers, or compounding oils or organic or inorganic 
pigments and dyes. Rubber compounding oils are well-known in the art and 
include both high saturates content oils and naphthenic oils. Preferred 
plasticizers are highly saturated oils, e.g. Tufflo.RTM. 6056 and 6204 oil 
made by Arco and naphthenic process oils, e.g. Shellflex.RTM. 371 oil made 
by Shell. The amounts of rubber compounding oil employed in the invention 
composition can vary from 0 to about 150 phr, preferably between about 0 
to about 100 phr, and most preferably between about 0 and about 60 phr. 
Optional components of the present invention are stabilizers which inhibit 
or retard heat degradation, oxidation, skin formation and color formation. 
Stabilizers are typically added to the commercially available compounds in 
order to protect the polymers against heat degradation and oxidation 
during the preparation, use and high temperature storage of the 
composition. 
Various types of fillers and pigments can be included in sealant and 
adhesive formulations. This is especially true for exterior sealants in 
which fillers are added not only to create the desired appeal but also to 
improve the performance of the sealant such as its weatherability. A wide 
variety of fillers can be used. Suitable fillers include calcium 
carbonate, clays, talcs, silica, zinc oxide, titanium dioxide and the 
like. The amount of filler usually is in the range of 0 to about 65% w 
based on the solvent free portion of the formulation depending on the type 
of filler used and the application for which the sealant is intended. An 
especially preferred filler is titanium dioxide. 
If the adhesive or sealant will be applied from solvent solution, the 
organic portion of the formulation will be dissolved in a solvent or blend 
of solvents. Aromatic hydrocarbon solvents such as toluene, xylene, or 
Shell Cyclo Sol 53 are suitable. Aliphatic hydrocarbon solvents such as 
hexane, naphtha or mineral spirits may also be used. If desired, a solvent 
blend consisting of a hydrocarbon solvent with a polar solvent can be 
used. Suitable polar solvents include esters such as isopropyl acetate, 
ketones such as methyl isobutyl ketone, and alcohols such as isopropyl 
alcohol. The amount of polar solvent used depends on the particular polar 
solvent chosen and on the structure of the particular polymer used in the 
formulation. Usually, the amount of polar solvent used is between 0 and 
50% w in the solvent blend. 
Combinations of primary and secondary antioxidants are preferred. Such 
combinations include sterically hindered phenolics with phosphites or 
thioethers, such as hydroxyphenylpropionates with aryl phosphates or 
thioethers, or amino phenols with aryl phosphates. Specific examples of 
useful antioxidant combinations include 
3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane (Irganox.RTM. 1010 
from Ciba-Geigy) with tris(nonylphenyl)phosphite (Polygard.RTM. HR from 
Uniroyal), Irganox.RTM. 1010 with bis(2,4-di-t-butyl)pentaerythritol 
diphosphite (Ultranox.RTM. 626 from Borg-Warner). 
Additional stabilizers known in the art may also be incorporated into the 
composition. These may be for protection during the life of the article 
against, for example, oxygen, ozone and ultra-violet radiation. However, 
these additional stabilizers should be compatible with the essential 
stabilizers mentioned hereinabove and their intended function as taught 
herein. 
All adhesive and sealant compositions based on the polymers of this 
invention will contain some combination of the various formulating 
ingredients disclosed herein. No definite rules can be offered about which 
ingredients will be used. The skilled formulator will choose particular 
types of ingredients and adjust their concentrations to give exactly the 
combination of properties needed in the composition for any specific 
adhesive, coating or sealant application. 
Adhesives are frequently thin layers of sticky compositions which are used 
in protected environments (adhering two substrates together). Therefore, 
unhydrogenated epoxidized polymers will usually have adequate stability so 
resin type and concentration will be selected for maximum stickiness 
without great concern for stability, and pigments will usually not be 
used. 
Sealants are gap fillers. Therefore, they are used in fairly thick layers 
to fill the space between two substrates. Since the two substrates 
frequently move relative to each other, sealants are usually low modulus 
compositions capable of withstanding this movement. Since sealants are 
frequently exposed to the weather, the hydrogenated epoxidized polymers 
are usually used. Resins and plasticizers will be selected to maintain low 
modulus and minimize dirt pick-up. Fillers and pigment will be selected to 
give appropriate durability and color. Since sealants are applied in 
fairly thick layers, solvent content is as low as possible to minimize 
shrinkage. 
A formulator skilled in the art will see tremendous versatility in the 
polymers of this invention to prepare adhesives and sealants having 
properties suitable for many different applications. 
The adhesive and sealant compositions of the present invention can be 
prepared by blending the components at an elevated temperature, preferably 
between about 50.degree. C. and about 200.degree. C., until a homogeneous 
blend is obtained, usually less than three (3) hours. Various methods of 
blending are known to the art and any method that produces a homogenous 
blend is satisfactory. The resultant compositions may then be used in a 
wide variety of applications. Alternatively, the ingredients may be 
blended into a solvent. 
The adhesive compositions of the present invention may be utilized as many 
different kinds of adhesives, for example, laminating adhesives, pressure 
sensitive adhesives, tie layers, hot melt adhesives, solvent borne 
adhesives and waterborne adhesives in which the water has been removed 
before curing. The adhesive can consist of simply the polymer or, more 
commonly, a formulated composition containing a significant portion of the 
polymer along with other known adhesive composition components. A 
preferred method of application will be hot melt application at a 
temperature around or above 100.degree. C. because hot melt application 
above 100.degree. C. minimizes the presence of water and other low 
molecular weight inhibitors of cationic polymerization. The adhesive can 
be heated before and after cure to further promote cure or post cure. 
Radiation cure of hot adhesive is believed to promote faster cure than 
radiation cure at lower temperatures. The unhydrogenated precursors may 
also be used in these applications. 
Preferred uses of the present compositions are the preparation of 
pressure-sensitive adhesive tapes and the manufacture of labels. The 
pressure-sensitive adhesive tape comprises a flexible backing sheet and a 
layer of the adhesive composition of the instant invention coated on one 
major surface of the backing sheet. The backing sheet may be a plastic 
film, paper or any other suitable material and the tape may include 
various other layers or coatings, such as primers, release coatings and 
the like, which are used in the manufacture of pressure-sensitive adhesive 
tapes. The unhydrogenated precursors may also be used in these 
applications. 
Sealant compositions of this invention can be used for many applications. 
Particularly preferred is their use as gap fillers for constructions which 
will be baked (for example, in a paint baking oven) after the sealant is 
applied. This would include their use in automobile manufacture and in 
appliance manufacture. Another preferred application is their use in 
gasketing materials, for example, in lids for food and beverage 
containers. The unhydrogenated precursors may also be used in these 
applications.

EXAMPLES 
Tables I through III demonstrate the advantages available from dissimilar 
arm block copolymers in pressure sensitive adhesive applications. 
Table IA illustrates two useful molecular structures which are within the 
invention, as well as a control polymer which is widely used in the 
adhesives industry. Molecular weights and other descriptive data are given 
in Table IB. The polymers within the invention contain side chains of 
polyisoprene (2 and 4, respectively) and a saturated main chain of 
poly(ethylene/butylene) terminated with polystyrene blocks. The side 
chains and main chain are joined at the mid-point of the main chain 
through a coupling agent. The control polymer is predominantly S--EB--S 
triblock (no side chains), with 30% or less of S--EB diblock. 
The total molecular weights of the polymers of the invention bracket that 
of the control polymer. Diblock content is lower than that of the control. 
The coupling efficiency figures of 87 percent and 89 percent, respectively 
indicate diblock content is .ltoreq.13 percent and .ltoreq.11 percent, 
respectively. In spite of the similarity in molecular weight and lower 
diblock content, the solution viscosity of the dissimilar arm polymers is 
much lower than that of the control (Table IB). Compared to conventional 
100 percent unsaturated block copolymers used in the adhesives industry, 
the viscosity reduction is also striking. For example, the viscosity of 
KRATON.RTM. D1107 Rubber, a conventional polymer that has long been used 
in such applications, (20 percent in toluene) is 514 cps, compared to 180 
and 93 cps, respectively, for the invention polymers shown in Table IB. 
This viscosity reduction is valuable in both polymer manufacture and end 
use application; e.g., ability to use higher solids contents, less 
solvent, easier application, lower pumping energy requirements, etc. 
The polymers described in Table I were formulated in a pressure-sensitive 
adhesive formulation to glass transition temperatures of -20.degree. C. 
(Table II) and -15.degree. C. (Table III). Taken as a whole, the 
experimental polymers were superior to the control polymer in tack, peel 
strength and holding power to steel. Polymer #4918 was superior to the 
control in SAFT to Mylar. The superiority in tack was evident in 
qualitative finger tack comparisons as well as laboratory instrumental 
tack measurements. 
In another example, Polymer #4918 was compared to the same control polymer 
using formulations calculated to give a Tg of -15.degree. C. (Table III). 
In this case, #4918 was superior to the control in tack, peel strength and 
SAFT properties. It was somewhat inferior to the control in holding power 
to steel. 
The ability to obtain a combination of high adhesive performance at low 
molecular weight and viscosity is attributed to the superior phase 
separation between polystyrene endblocks and poly(ethylene-butylene) 
rubber blocks compared to polystyrene and unsaturated diene rubber blocks. 
TABLE I 
__________________________________________________________________________ 
Polymer Descriptions 
A. Polymer Structures - Examples 
##STR1## 
B. Polymer Molecular Conventional 
Parameters #4918 
#4844 
Polymer 
__________________________________________________________________________ 
Styrene block mol. wt., M 
9.3 
6.0 5.3 
Main chain rubber mol. wt., M 
50 46 86 
Double bonds in main chain hydrogenated, % 
&gt;99 &gt;99 &gt;99 
Side chain rubber mol. wt., M 
18 3.8 No side chains. 
Number of side chains 2 4 0 
Total mol. wt., M 94 73 86 
Polymeric Styrene Content, % 
17.9 
16.7 
13 
Coupling Efficiency, % 87 89 71 
Solution Viscosity, 20% wt. in toluene, cps 
180 93 1250 
__________________________________________________________________________ 
TABLE II 
__________________________________________________________________________ 
Properties of Adhesive Formulations 
(All formulated to Tg = -20.degree. C.) 
__________________________________________________________________________ 
A. 
Formulations 
Formulation Number R-108 R-084 R-110 
Base Polymer #4918 #4844 Conventional 
(Invention) 
(Invention) 
Polymer 
Base Polymer 100.0 100.0 100.0 
Hydrocarbon Resin (softening pt., 85.degree. C.).sup.1 
102.4 103.7 108.2 
Hydrocarbon Resin (softening pt., 18.degree. C.).sup.2 
144.5 146.4 152.8 
Hindered Phenolic.sup.3 Antioxidant 
1.0 1.0 1.0 
UV Stabilizer No. 1.sup.4 
0.25 0.25 0.25 
UV Stabilizer No. 2.sup.5 
0.25 0.25 0.25 
Total phr (parts per hundred rubber-the 
348.4 351.6 362.5 
polymer) 
B. 
Properties 
Rolling Ball Tack, cm 
1.3 2.3 1.9 
Polyken Probe Tack, kg 
2.1 2.0 1.8 
Loop Tack, oz/in 81 95 80 
180 Deg. Peel Strength, pli 
5.8 8.0 5.4 
Holding Power/Steel, min 
180 125 67 
Holding Power/Kraft, min 
1.4 3.5 3.5 
SAFT, Mylar, deg. C. 
64 48 50 
SAFT, Kraft, deg. C. 
&lt;38 &lt;38 &lt;38 
Thickness of Adhesive Film, mils 
1.4 1.5 1.5 
__________________________________________________________________________ 
.sup.1 Regalrez 1085; Hercules, Inc.; hydrogenated styrene/alpha methyl 
styrene copolymers 
.sup.2 Regalrez 1018; Hercules, Inc.; hydrogenated styrene/alpha methyl 
styrene copolymers 
.sup.3 Irganox 1010; CIBAGeigy Corp. 
.sup.4 Tinuvin 327; CIBAGeigy Corp. 
.sup.5 Tinuvin 770; CIBAGeigy Corp. 
TABLE III 
__________________________________________________________________________ 
Properties of Adhesive Formulations 
Formulated to Tg = -15 deg. C. 
__________________________________________________________________________ 
A. Formulations 
Formulation Number R-131 R-117 
Base Polymer #4918 Conventional 
(Invention) 
Polymer 
Base Polymer 100.0 100.0 
Hydrocarbon Resin (softening pt., 85.degree. C.).sup.1 
132.9 138.0 
Hydrocarbon Resin (softening pt., 18.degree. C.).sup.2 
100.5 95.2 
Hindered Phenolic.sup.3 Antioxidant 
1.0 1.0 
UV Stabilizer No. 1.sup.4 
0.25 0.25 
UV Stabilizer No. 2.sup.5 
0.25 0.25 
Total phr 334.9 334.7 
B. Properties 
Rolling Ball Tack, cm 
2.6 7.2 
Polyken Probe Tack, kg 
2.3 0.83 
Loop Tack, oz/in 101 95 
180 Deg. Peel Strength, pli 
7.3 5.9 
Holding Power/Steel, min 
225 398 
Holding Power/Kraft, min 
6.3 6.7 
SAFT/Mylar, deg. C. 70 62 
SAFT/Kraft, deg. C. 55 38 
Thickness of Adhesive Film, mils 
1.5 1.4 
__________________________________________________________________________ 
.sup.1 Regalrez 1085; Hercules, Inc.; hydrogenated styrene/alpha methyl 
styrene copolymers 
.sup.2 Regalrez 1018; Hercules, Inc.; hydrogenated styrene/alpha methyl 
styrene copolymers 
.sup.3 Irganox 1010; CIBAGeigy Corp. 
.sup.4 Tinuvin 327; CIBAGeigy Corp. 
.sup.5 Tinuvin 770; CIBAGeigy Corp. 
Though the polymers of this invention contain unsaturated arms of 
homopolymers, they behave primarily like the fully saturated block 
copolymers commonly used in adhesives when subjected to heat and 
accelerated weathering. Table IV compares the viscosity and color 
stability of a polymer of the invention with those of a conventional 
saturated polymer (see Table I) and a conventional unsaturated polymer 
widely used in the industry (KRATON.RTM. D1107 Rubber, a linear S--I--S of 
160M molecular weight and 15 percent styrene content made by Shell Oil 
Company). Adhesive compositions based on these three polymers were 
subjected to a temperature of 350.degree. F. for 96 hours, with viscosity 
and color measured at various intervals. Such a test is important in 
predicting the behavior of hot melt adhesive compositions. The polymer of 
the invention approximated the behavior of the fully saturated polymer in 
maintaining viscosity and color over time, and was markedly superior to 
the unsaturated polymer in these respects. 
TABLE IV 
______________________________________ 
Melt Stability 
Conventional 
Invention 
Conventional 
Base Polymer Saturated Polymer Unsaturated 
of Formulation 
Polymer.sup.(1) 
#4918.sup.(1) 
Polymer.sup.(2) 
______________________________________ 
Time at 350 deg. F. hr. 
Melt Viscosity, cps.sup.(3) 
0 52,200 13,920 71,800 
8 52,300 13,820 41,800 
24 52,200 13,150 27,530 
48 54,200 10,210 12,550 
96 52,150 10,730 19,100 
Gardner Color 
0 1 1 10 
8 3 3 13 
24 4 4 14 
48 6 10 17 
96 6 11 15 
______________________________________ 
.sup.(1) Formulation: Polymer, 100 parts by weight (pbw); Regalrez 1085 
resin, 125 pbw; Regalrez 1018 resin, 20 pbw; Irganox 1010, 1.0 pbw; 
Tinuvin 770, 0.25 pbw; Tinuvin 327, 0.25 pbw. 
.sup.(2) Formulation: Polymer, 100 pbw; Piccotac 95 resin, 135 pbw; 
Shellflex 371 oil, 15 pbw; Irganox 1010, 1.0 pbw; Tinuvin 770, 0.25 pbw; 
Tinuvin 327, 0.25 pbw. 
.sup.(3) Brookfield viscosity, Model RVTD. 
For consideration as a polymer for weatherable adhesives, the invention 
polymers should withstand outdoor aging conditions as well as conditions 
in laboratory devices designed to predict outdoor aging stability. Table V 
shows that an adhesive based on a polymer of the invention maintains peel 
strength over time at least as well as a conventional saturated 
polymer-based adhesive. Furthermore, the mode of failure remains a clean 
adhesive peel (which is desirable) whereas an adhesive based on 
unsaturated polymer begins to fail cohesively (that is, leaves a layer of 
adhesive on both the substrate and backing film) after a short aging 
period. This behavior of the unsaturated polymer-based adhesive is 
probably due to weakening caused by degradation. Similar conclusions can 
be drawn from results of accelerated aging studies, which are shown in 
Table VI. 
TABLE V 
______________________________________ 
Outdoor Aging 
(45 deg. to south) 
Pressure Sensitive Tape 
Conventional 
Invention Conventional 
Base Polymer 
Saturated Polymer Unsaturated 
of Formulation 
Polymer.sup.(1) 
#4918.sup.(1) 
Polymer.sup.(2) 
______________________________________ 
Aging time, days 
180 deg. Peel Strength, pli 
0 4.1A.sup.(3) 
6.4A 9.3A 
Aged through Glass 
15 6.0A 5.7A 9.5C 
30 4.3A 5.1A 6.9C 
Aged through Mylar 
15 5.4A 6.3A 10.8C 
30 4.6A 5.5A 7.5C 
______________________________________ 
.sup.(1) See footnote 1, Table IV. 
.sup.(2) See footnote 2, Table IV. 
.sup.(3) A signifies adhesive failure; C, cohesive failure. 
TABLE VI 
______________________________________ 
Accelerated Aging 
(Laboratory QUV Cabinet, UVB 313 lamp) 
Pressure Sensitive Tape 
Conventional 
Invention Conventional 
Base Polymer 
Saturated Polymer Unsaturated 
of Formulation 
Polymer.sup.(1) 
#4918.sup.(1) 
Polymer.sup.(2) 
______________________________________ 
Aging time, hr. 
180 deg. Peel Strength, pli 
0 3.9A.sup.(3) 
6.8A 8.8A 
Aged through Glass 
100 5.4A 5.1A 6.5C 
300 2.7A 5.4A 4.9C 
500 3.8A 3.1A --.sup.(4) 
______________________________________ 
.sup.(1) See footnote 1, Table IV. 
.sup.(2) See footnote 2, Table IV. 
.sup.(3) A signifies adhesive failure; C, cohesive failure. 
.sup.(4) Backing failed. 
Incorporating unsaturated polymer arms into a basically saturated block 
copolymer structure adds the potential for crosslinking of the system, 
with its attendant benefits in resistance to shear and heat in the 
application. The invention polymer is amenable to crosslinking using a 
variety of techniques. Table VII illustrates that electron beam (EB) 
radiation crosslinks an adhesive composition based on the invention 
polymer #4918 at doses of 10 and 16 megarads (gel contents of 38 percent 
and 81 percent of base polymer, respectively, are attained). Shear 
adhesion failure temperature (SAFT) is markedly improved without any major 
loss in tack properties. 
The presence of unsaturated polymer arms in the otherwise saturated 
invention block copolymer increases the number of reaction sites for 
functionalization. The functionalized polymer frequently has improved 
adhesion properties because of its increased polarity. Functionalized 
polymers also may be more reactive in radiation-induced crosslinking 
processes. In the example of Table VII, electron beam radiation was used 
to crosslink an adhesive formulation based on an invention polymer that 
had been epoxidized. Crosslinking occurred at relatively low doses (as 
little as 2 or 6 megarads with gel contents of 14 percent and 74 percent 
of base polymer, respectively). Holding power and SAFT values were 
increased substantially with little or no effect on tack properties except 
at very high doses. 
TABLE VII 
__________________________________________________________________________ 
Electron Beam (EB) Crosslinking.sup.(1) 
Invention Polymer #4918, 
Invention Polymer #4918 
Epoxidized.sup.(2) 
Dose, megarads 
0 2 6 10 16 0 2 6 10 16 
__________________________________________________________________________ 
Gel, % of base 
0 0 0 38 81 0 14 74 97 88 
polymer 
Rolling Ball Tack, cm 
1.8 
1.7 
1.8 
2.3 
2.3 
3.1 
2.3 
2.6 
4.7 6.8 
Loop Tack, oz/in 
51 38 54 48 48 57 75 61 58 51 
Polyken Probe Tack, 
.82 
.89 
.92 
.90 
.65 
.64 
.76 
.73 
.40 .52 
kg 
180 deg. Peel Str., pli 
3.5 
2.6 
2.3 
2.2 
2.3 
3.8 
2.5 
2.2 
2.2 2.0 
Holding Power to 
197 
489 
574 
152 
183 
14 75 778 
&gt;7000 
-- 
Steel, min.sup.(3) 
SAFT.sup.(4) on Mylar, 
82 87 91 114 
127 
82 83 113 
118 114 
deg. C. 
__________________________________________________________________________ 
.sup.(1) Formulation: Polymer, 100 pbw; Regalrez 1085 resin, 54 pbw; 
Regalrez 1018 resin, 68 pbw; Polygard HR antioxidant, 1.0 pbw. EB curing 
was accomplished on an Energy Sciences, Inc., Electron Beam Unit, Model 
CB150. 
.sup.(2) Epoxidized to 1.26 meq/g by method described in U.S. Pat. No. 
5,229,464. 
.sup.(3) 0.5 in. .times. 0.5 in bond, 2 kg weight. 
.sup.(4) Shear Adhesion Failure Temperature of lap shear bond, 1 in 
.times. 1 in, 2 kg weight. 
Similarly, epoxidized and non-epoxidized block copolymers of the invention 
crosslink readily in adhesive formulations under ultraviolet light (UV). 
Table VIII illustrates results obtained using a Linde Photocure System 
from Union Carbide Corporation. Substantial crosslinking took place on the 
epoxidized version even at the lowest dosages (highest belt speeds shown 
in Table VIII). 
TABLE VIII 
______________________________________ 
Crosslinking by Ultraviolet Light Radiation.sup.(1) 
Invention 
Invention 
Base Polymer Polymer Polymer #4918 
of Formulation #4918.sup.(1) 
Epoxidized.sup.(3)(4) 
______________________________________ 
Gel, % of base polymer 
No dose 3.3 3.2 
Belt Speed, ft/min.sup.(5) 
56 13 89 
44 -- 87 
32 9 90 
21 6 92 
7.5 41 90 
3.8 56 92 
______________________________________ 
.sup.(1) Irradiated with UV light by the method described in U.S. Pat. No 
5,229,464 which is herein incorporated by reference (Linde Photocure 
Systems, Union Carbide Corp.). 
.sup.(2) Formulation: Polymer, 100 pbw; Regalrez 1085 resin, 58 pbw; 
Regalrez 1018 resin, 65 pbw; Polygard HR antioxidant, 1.0 pbw; Irgacure 
651 photoinitiator, 1.0 pbw; 1,6 hexanediol diacrylate crosslinker, 7.5 
pbw. 
.sup.(3) Epoxidized to 1.26 meq/g by the method described in U.S. Pat. No 
5,229,464. 
.sup.(4) Formulation: Polymer, 100 pbw; Regalrez 1085 resin, 54 pbw; 
Regalrez 1018 resin, 68 pbw; Polygard HR antioxidant, 1.0 pbw; Cyracure 
UVI 6974 cationic photoinitiator, 1.1 pbw. 
.sup.(5) The slower the belt speed, the higher the radiation dose. 
In Table IX, the results of a crosslinking study are presented in which 
initiation and propagation are chemical in nature, unaided by any form of 
radiation. The crosslinking agent is a urea-formaldehyde resin and the 
reaction is catalyzed by dodecylbenzene sulfonic acid. Gel contents of 80 
to 90 percent are created over 20 to 40 minutes at 149.degree. to 
177.degree. C. These results are illustrative of the fact that the 
unsaturated arms of the invention polymers will undergo a variety of 
chemical reactions leading to network formation. Such structures improve 
service temperatures, solvent resistance and shear properties in 
adhesives, sealants, coatings, and many other applications. 
TABLE IX 
______________________________________ 
Chemical Crosslinking 
______________________________________ 
Formulation 
Invention polymer #4918 
100.0 pbw 
Beetle .RTM. 80.sup.(1) 
11.1 pbw 
Cycat .RTM. 600.sup.(2) 
1.1 pbw 
Irganox 1010 antioxidant 
0.5 pbw 
Polygard HR antioxidant 
0.5 pbw 
113.2 
______________________________________ 
Cure Time, Gel (polymer basis) 
Cure Temp., .degree.C. 
min. Content, % 
______________________________________ 
149 20 80 
149 40 90 
177 20 87 
______________________________________ 
.sup.(1) Urea-formaldehyde resin, American Cyanamid Co. 
.sup.(2) Catalyst, 70% solution of dodecylbenzene sulfonic acid in 
isopropanol, American Cyanamid Co.