PRESSURE SENSITIVE ADHESIVES AND ADHESIVE ARTICLES

COLLES DE CONTACT, ET ARTICLES GOMMES

English Abstract

ABSTRACT
Normally tacky, pressure sensitive adhesive
compositions comprise one or more polymers containing
pendant functional groups attached to a polymer
backbone and having the formula:
<IMG>
in which R1 is a divalent organic radical at least 3
atoms in length, and X is organoacyl or cyano, and
wherein said polymer is selected from the group
consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at
least about 40 weight percent of an
alkenyl or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized

olefinically unsaturated carboxylic
acid ester monomers,
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof.
Such polymers have improved cohesive strength with
little or no detriment to adhesive tack or adhesion,
and these improvements are realized without the
necessity of incorporating crosslinking monomers such
as N-methylolamides or other crosslinking agents.
Pressure sensitive adhesive, water-based emulsions,
hot melts and solutions containing such polymers and
adhesive articles having at least a portion of one
surface thereof coated with such adhesives are also
provided.

Claims

-41-
WE CLAIM:
1. A normally tacky and pressure-sensitive
adhesive composition comprising a polymer containing
at least one polymerizable functional monomer of the
formula:
<IMG>
in which R1 is a divalent organic radical of at least
3 atoms in length, R5 and R6 are independently selected
from hydrogen, hydroxy, halo, thio, amino or monovalent
organic radicals, and X is - CO - R4 or - CN wherein
R4 is hydrogen or a monovalent organic radical, wherein
said polymer is selected from the group consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at
least about 40 weight percent of an
alkenyl or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized

-42-
olefinically unsaturated carboxylic
acid ester monomers;
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof,
2. The adhesive composition defined in
claim 1 wherein said polymer has a Tg of about 0° C.
or less and comprises about 0.1 to about 40 weight
percent of said functional monomer.
3. The adhesive composition defined in
claim 1 wherein said polymer has a Tg of about 0° C.
or less and said composition comprises at least about
20 weight percent of said conjugated diolefin polymer
comprising at least 5 weight percent of said mono-
aromatic monomer and at least about 0.1 weight percent
of said functional monomer.
4. The composition defined in claim 3
wherein said aromatic monomer comprises styrene, said
conjugated diolefin comprises a member selected from
the group consisting of butadiene, isoprene and
combinations thereof, and said composition further
comprises a tackifier.
5. The composition defined in claim 3
wherein said polymer further comprises about 0.2 to
abnut 10 weight percent of a member selected from the
group consisting of acrylic acid, itaconic acid, and
combinations thereof.
6. The composition defined in claim 1

-43-
wherein said polymer further comprises a member
selected from the group consisting of acrylic acid,
itaconic acid, and combinations thereof.
7. The adhesive composition defined in
claim 1 wherein said polymer comprises about 0.1 to
about 10 weight percent of said functional monomer.
8. The adhesive composition defined in
claim 1 wherein said polymer comprises about 0.1 to
about 5 weight percent of said functional monomer.
9. The adhesive composition defined in
claim 1 having a shear holding value of at least about
500 minutes at 75° F.
10. The adhesive composition defined in
claim 6 having a shear holding value of at least about
500 minutes at 75° F. and a loop tack value of at
least about 0.8 pound per half inch.
11. The adhesive composition defined in
claim 1 wherein said polymer is substantially free of
polyvalent metals, compounds and complexes.
12. The adhesive composition defined in
claim 1 wherein said polymer is substantially free of
crosslinking agents.
13. The adhesive composition defined in
claim 12 having a shear holding value of at least 50
minutes at 75° F.
14. The adhesive composition defined in
claim 1 wherein R1 is a divalent organic radical 3 to
about 40 atoms in length, and X is - CO - R4.

-44-
15. The adhesive composition defined in
claim 1 wherein said polymer comprises at least about
0.1 weight percent of at least one functional monomer
having the formula:
<IMG>
wherein R4, R5, and R6 are as defined in claim 1, R3
is a divalent organic radical, Y and Z are indepen
dently selected from the group consisting of 0, S, and
NR7, and R7 is H or monovalent organic radical.
16. The adhesive composition defined in
claim 13 wherein R4 is hydrogen or alkyl having up to
about 8 carbon atoms, R3 is a divalent organic radical
at least 2 atoms in length, and said composition
comprises at least about 20 weight percent of said
conjugated diolefin polymer containing at least 5
weight percent of said monoaromatic monomer.
17. The adhesive composition defined in
claim 16 wherein each of Y and Z is 0.
18. The adhesive composition defined in
claim 1 wherein said polymer comprises about 0.1 to
about 10 weight percent of a member selected from the
group consisting of acetoacetoxyethyl methacrylate,
acetoacetoxyethyl acrylate, and combinations thereof.
19. The adhesive composition defined in
claim 1 wherein said polymer comprises less than about
1 weight percent of an N-methylolamide.
20. The adhesive composition defined in
claim 1 wherein said polymer is substantially free of
N-methylolamides.

-45-
21. The adhesive composition defined in
claim 1 wherein said polymer comprises a polymerizable
carboxylic acid monomer.
22. The adhesive composition defined in
claim 1 wherein said polymer further comprises at
least about 0.1 weight percent of a polymerizable acid
selected from the group consisting of olefinically
unsaturated carboxylic acids having up to about 10
carbon atoms, sulfoalkyl esters of said olefinically
unsaturated acids, and combinations thereof.
23. A normally tacky and pressure sensitive
adhesive composition comprising a polymer containing
pendant functional groups of the formula:
<IMG>
wherein R1 is a divalent organic radical at least 3
atoms in length, and R4 is H or a monovalent organic
radical, and wherein said polymer is selected from the
group consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at least
about 40 weight percent of an alkenyl

-46-
or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized
olefinically unsaturated carboxylic
acid ester monomers,
(4) alkenyl ether polymers comprising at
leastabout 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof
24. The adhesive composition defined in
claim 23 wherein said polymer comprises at least about
0.1 weight percent of said pendant functional groups.
25. The adhesive composition defined in
claim 24 having a sheer holding value of at least
about 1,000 minutes at 75° F.
26. The adhesive composition defined in
claim 23 wherein said polymer is substantially free of
crosslinking agents and residues thereof.
27. The adhesive composition defined in
claim 23 wherein R1 is of the formula:
<IMG>
wherein Y and Z are independently selected from the
group consisting of oxygen, sulfur, and NR7, R3 is a
divalent organic radical at least about 2 atoms in
length, and R7 is H or hydrocarbyl.

-47-
28. The adhesive composition defined in
claim 27 wherein R3 is selected from the group
consisting of substituted and unsubstituted alkylene,
alkylene-oxy, alkyleneimine and alkylene-thio radicals
29. The adhesive composition defined in
claim 23 wherein R1 is an ethylene radical, R4 is a
methyl radical, and said polymer comprises about 0.1
to about 10 weight percent of said functional monomer.
30. The adhesive composition defined in
claim 23 wherein said polymer further comprises at
least about 0.1 weight percent of a polymerizable,
olefinically unsaturated carboxylic acid monomer.
31. A normally tacky and pressure sensitive
adhesive composition comprising a polymer which
contains at least about 0.1 weight percent pendant
functional groups of the formula:
<IMG>
wherein R3 is a divalent organic radical at least 2
atoms in length, and R4 is hydrogen or an organic
radical, and wherein said polymer is selected from the
group consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,

-48-
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at least
about 40 weight percent of an alkenyl
or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized
olefinically unsaturated carboxylic
acid ester monomers,
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof.
32. The adhesive composition defined in
claim 31 wherein said polymer comprises at least about
0.1 weight percent of a polymerizable, olefinically
unsaturated carboxylic acid monomer.
33. A normally tacky and pressure sensitive
adhesive composition comprising a polymer containing
pendant functional groups attached to the polymer
backbone having the formula:
<IMG>
in which R1 is a divalent organic radical at least 3
atoms in length, and X is - CO - R4 or - CN wherein
R4 is hydrogen or a monovalent organic radical, and

-49-
wherein said polymer is selected from the group
consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at least
about 40 weight percent of an alkenyl
or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized
olefinically unsaturated carboxylic
acid ester monomers,
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof.
34. A pressure sensitive adhesive composition
comprising a water-based latex comprising a continuous
aqueous medium containing dispersed particles of a
polymer comprising at least about 0.1 weight percent

-50-
of at least one polymerizable functional monomer of
the formula:
<IMG>
in which R1 is a divalent organic radical of at least
3 atoms in length, R5 and R6 are independently selected
from hydrogen, hydroxy, halo, thio, amino or monovalent
organic radicals, and X is - CO - R4 or - CN wherein
R4 is hydrogen or a monovalent organic radical, and
wherein said polymer is selected from the group
consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at least
about 40 weight percent of an alkenyl
or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized
olefinically unsaturated carboxylic
acid ester monomers,

-51-
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof.
35. An adhesive article coated on at least
a portion of one surface thereof with a normally tacky
and pressure sensitive adhesive composition comprising
a polymer containing at least one polymerizable
functional monomer of the formula:
<IMG>
in which R1 is a divalent organic radical at least 3
atoms in length, R5 and R6 are independently selected
from hydrogen, hydroxy, halo, thio, amino or monovalent
organic radicals, and X is - CO - R4 or - CN wherein
R4 is hydrogen or a monovalent organic radical,
wherein said polymer is selected from the group
consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at least
about 40 weight percent of an alkenyl

-52-
or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized
olefinically unsaturated carboxy1ic
acid ester monomers,
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof.
36. The article defined in claim 35 wherein
said polymer comprises about 0.1 to about 5 weight
percent of said functional monomer.
37. The article defined in claim 35 comprising
a flexible backing and having a shear holding value of
at least about 50 minutes at 75° F. and a loop tack
value of at least about 0.8 pound per half inch.
38. The article defined in claim 35 wherein
said polymer is substantially free of polyvalent
metals, compounds and complexes.
39. The article defined in claim 35 wherein
said polymer is substantially free of crosslinking
agents.
40. The article defined in claim 35 wherein
R1 is a divalent organic radical 3 to about 40 atoms
in length, and X is - CO - R4.

-53-
41. The article defined in claim 35 wherein
said polymer comprises about 0.1 to about 10 weight
percent of a member selected from the group consisting
of acetoacetoxyethyl methacrylate, acetoacetoxyethyl
acrylate, and combinations thereof; and said adhesive
composition comprises at least about 20 weight percent
of said conjugated diolefin polymer containing at
least about 5 weight percent of said monoaromatic
monomer.
42. The article defined in claim 35 wherein
said polymer further comprises at least about 0.5
weight percent of a polymerizable acid selected from
the group consisting of olefinically unsaturated
carboxylic acids having up to about 10 carbon atoms,
sulfoalkyl esters of said olefinically unsaturated
acids, and combinations thereof.
43. The adhesive article defined in claim
comprising (a) said conjugated diolefin polymer
comprising at least about 50 weight percent of said
conjugated diolefin monomer, at least about 5 weight
percent of said alkenyl substituted monoaromatic
monomer, about 0.1 to about 10 weight percent of said
functional monomer, and a member selected from the
group consisting of acrylic acid, itaconic acid, and
combinations thereof, and (b) a tackifier.
44. A normally tacky, pressure-sensitive,
hot melt adhesive composition comprising a polymer
containing at least one polymerizable functional
monomer of the formula:
<IMG>

-54-
in which R1 is a divalent organic radical of at least
3 atoms in length, R5 and R6 are independently selected
from hydrogen, hydroxy, halo, thio, amino or monovalent
organic radicals, and X is - CO - R4 or - CN wherein
R4 is hydrogen or a monovalent organic radical,
wherein said polymer is selected from the group
consisting of
(1) conjugated diolefin polymers comprising
at least about 30 weight percent of one
or more conjugated diene monomers
having 4 to about 8 carbon atoms and 0
to about 70 weight percent of one or
more alkenyl-substituted monoaromatic
monomers,
(2) olefin ester interpolymers
comprising at least about 1 weight
percent of a monoolefin monomer having
up to about 4 carbon atoms and at least
about 40 weight percent of an alkenyl
or alkenol ester of a saturated
carboxylic acid,
(3) olefinically unsaturated carboxylic
acid ester polymers comprising at least
about 40 weight percent polymerized
olefinically unsaturated carboxylic
acid ester monomers,
(4) alkenyl ether polymers comprising at
least about 30 weight percent alkenyl
ether monomer units, and
(5) combinations thereof.

Description

~ 0~3
PRESSURE SENSITIVE ADHESIYES AND ADHSIVE ARTICLES
BACKGROUND r
Field of the Invention
This invention relates to the field o~
pressure sensitive adhesives and to articles
comprising such adhesives.
In~roduction
Normally tacky, pressure sensitive adhesives
~PSAs) are used in the ~anufacture af ~ var1ety of
articles such as adhesive tapes and other materials
which are intended to be easily attachable to another
substrate by the application of pressure alone. Many
adhesives preferably have a balance of one or more
properties such as tackiness at the temperature o~
use, adhesion (peel resistance~, cohesion (shear
resistance), elongation, elasticity, color clarity and
color stability, and resistance to sunlight and other
ultraviolet and degrading radiation sources.
2~ Maintaining the requisite balance of such properties
while improving one or more characteristics of such
pressure sensitive adhesives is both difficult and
unpredictable. Any modification of adhesive
co~positions which improves one adhesive property may
detrimentally affect one or more other desirable
properties. For instance, it is difficult to improve
an adhesive's shear strength w;thout reducing one or
more other desirable properties.
Homopolymers and ;nterpolymers of a variety
o~ monomers are useful as pressure sensitive adhesives
when applied to a backing as solutions, dispersions
~;

~'~'7~3~3
-2-
(emulslons) ~nd/or hot melts. However, many PSA
applications require shear strength values higher than
those that can be provided by otherwise useful
polymers. Some appllcations requlre shear strength
values of at least about 50 minutes and h19her, ~.e,
on the order of 500 to 10,000 minutes (determtned by
the shear value test described hereinafter). While
there are various ways of improving PSA shear
strength, many if not all of these detrimentally
affect one or more other desirable properties.
Polymer molecular weight can be increased to improve
shear strength, but this route generally reduces tack
and adhesion. Polar monomers, such as polymerizable
carboxylic acids~ often increase cohesive strength but
also may result in low adhesion and tack.
Cross-linking monomers, such as the N-methylol amides,
or other crosslinking agents are generally expensive
and they may reduce tack and adhesion. Their use
also may reduce processability and may impair other
properties such as clarity, color stability and UY
stability.
The suitability of pressure sensitive
adhesive compositions is also influenced by the ease
of manufacture of both the adhesive and of artic1es
containing the adhesive and by environmental and
personnel safety hazards. For instance, PSAs are
often applied to a backing as hot ~elts, polymer
solutions or as dispersions of a polymer in an aqueous
medium. Such solutions and dispersions must possess
properties which facilitate their use in the
manufac~ure of PSA-containing articles. Thus, the
melt, solution or dispersion9 as well as the polymer
per se, must adequately wet the backing to assure
adequate adhesive distribution, coverage and bonding
to the backing.

f
3 ~ ~7t7a:~3
The chemical composition of the PSA polymer
carr~ers (when used) is also signlficant for several
reasons. Solvents other than water are beco~ing more
and more undesirable due to solvent expense and the
cost and hazards involved In controlling solvent
vapors. Yet such solvents are often necessary ~or
adequate distribution and handling of polymers that
cannot be employed effectively in water-based systems.
Thus~ water-based polymer latexes are much preferred
in the adhesive manufacturing industry provided that
the necessary physical and chemical properties of the
finished article can be achieved. However,
substitution of water-based latexes or hot melts ~or
solvent-based polymers may reduce one or more physical
properties.
N-methylol amide functional groups and other
crosslinking monomers and agents are known to improve
adhesive performance in several respects. However9
such polymers release formaldehyde upon curing or can
result in the presence of potentially toxic residues
in the finished article. In par~icular, N-methylol
amide-containing polymers release formaldehyde when
2~ cured, and they can result in formaldehyde residues in
the finished product. Such formaldehyde release and
residues are often undesirable since formaldehyde is
coming under ever increasing scrutiny in both the
workplace and home. It is particularly undesirable in
medical an~ personal contact applications, such as
adhesive bandages, and the state and federal
Occupational Health and Safety Administrations ~OSHA)
have set stringent formaldehyde exposure li~its for
industrial workers.
~5
Various rheological propert;es of water-base
latexes are particularly important with regard to the

!
_4 ~ ~ ~ 7 ~;3
suitabil~ty of such latexes for adhesive art~cle
manuf~cture. Latex particle s~ze and particle ~ze
distr~bution can signlficantly influence l~tex
physical prcperties wh~ch affect appl1cat~on o~ the
latex to a back~ng. Similarly, latex vtscos~ty can
limit latex util~ty in adhesive art~cle manufactllre
due to the inf1uence of viscos~ty on adhes~ve
distribution, filler loading (of the latex~ and
wetting of the adhesive artic1e backing.
Yet further demands are placed on the
chemical composition and physical properties of tow
temperature pressure sensitive adhesives, i.e.,
adhesives intended for use at relatively low
temperatures. Often, PSAs which haYe adequate
cohesive and adhesive strength at low temperatures are
so "gummy" at ambient conditions that they complicate
both adhesive handling at ambient temperatures and the
manufacture of adhesive-containing articles. Such
gummy adhesiYes also tend to "creep" and to "bleed-
through" labels and other backings.
rhUS 9 it can be seen that the physical and
chemical properties desired in adhesive compositions
and articles, and in the polymer solutions,
dispersions and melts employed in the manufacture of
adhesive articles, place various, sometimes
conflicting, demands on polymer composition and on the
polymer carrier, i.e, solvent or water, if usedO It
is desirable to obtain a polymer system~ preferably a
water-base or hot melt system, which possesses a
balance of properties suitable for the manufacture o~
pressure sensitive adhesives and PSA-containing
articles.

~ ~ 77 ~3
--5--
SUMMARY OF THE INYENTION
It has now been found ~ha~ pressure
sensit~Ye adhesives, and art~cles conta~n~ng pressure
sens~tive adhesives, having an improved balance o~ PSA
properties and, in particular, hav~ng improved shear
holding value and acceptable adhesive strength and
tack, can be obtained by employing, as a component of
the adhesive, a polymer having a Tg o~ about 0 C. or
less containing pendant functional groups of the
formula:
~ R1 - C. - CH2 - X (l)
wherein R1 is ~ divalent organic radical at least 3
atoms in length, and X is organoacyl or cyano.
Functional groups contdining different R1 and X
radicals san be contained in the same polymer
molecule, or polymers containing different R1 and X
groups can be blended in the same solution or disper-
sion. The polymers can be manufactured and applied to
backings either as solutions, aqueous dispersions or
hot melts, although aqueous dispersions and melts are
particularly preferred since they eliminate the costs
and hazards associated with solvents other ~han water.
Such pressure sensitive adhesives and adhesive articles
have an improved balance of properties. In particular,
they possess improved cohesive strength without
significant, if any, loss of adhesion or tack. They
are relatively clear, colorless materials (unlecs
intentionally colored by the addition of colorants),
and they possess adequate color stability and resis-
tance to sunlight and other ultraviolet sources. Theydo not require the use of crnsslinking agents

( ~
a ~77~ 3
--6--
and catalysts, such as N-methylol amide monomers,
although they may contain one or more of such
materlals. The low Tg polymers which are useful as
5 low temper~ture pressure sens1tive adhesives7 e.g.
adhesives intended ~or use at about 1~ C. or less~
have adequate cohesive and adhes~ve strength at low
temperatures yet are not excessively gummy at ambient
tempe ra t u res.
DETAILED DESCRIPTION OF THE INVENTION
.
Normally tacky and pressure sensitive
adhesive compositions are provided which comprise a
polymer containing pendant functional groups of the
formula:
Rl e CH2 x ~1)
wherein R1 is a divalent organic radical at least 3
atoms in length, and X is organoacyl or cyano, and
wherein the remainder of the polymer is selected from
(1) conjugated diolefin polymers comprising at least
about 50 wei~ht percent of one or more conjugated
diene monomers having 4 to about 8 carbon atoms and 0
to about 50 weight percent of one or more
alkenyl-substituted monoaromatic monomers, (2)
olefin ester interpolymers comprisin~ at least about 1
weight percent of a monoolefin monomer havin~ up to
about 4 carbon atoms and at least about 40 weight.
percent of an alkenyl or alkenol ester of a saturated
carboxylic acid, (3) olefinically unsaturated
carboxylic acid ester polymers comprising at least
about 40 weight percen~ polymerized olefinically
unsaturated carboxylic acid ester monomers 9 ~4)
alkenyl ether polymers containing at least about 30
weight percent alkenyl ether monomer units, and ~5)

.
~ ~77083
--7-
comb~n~tlons thereof. Functlonal groups conta~n1ng
dlfferent R1 and X radlcals can be contained ~n the
same polymer molecule~ or polymers contaln~ng
different R1 and X groups can be blended ~n the same
solutlon or dispersion. It ls essential only that the
useful poly~ers (1) contain functional groups
containing elther two carbonyl ~roups or a carbonyl
and a cyano group separated by a single methylene
group, as illustrated, and (2) the methylene group is
separated from the polymer main chain (backbone) by at
least 4 atoms (R1 plus the "interior" carbonyl group).
Thus, R1 is at least 3 atoms in length; i.e., the
shortest link between the interior carbonyl group and
the polymer backbone is at least 3 atoms long.
Otherwise, the molecular weight, structure and
elemental composition of R1 does not negate the
effectiveness of the dual keto or keto-cyano
functionality of the pendant side chains. Thus, R1
can be of any molecular weight sufficient to allow
incorporation of the pendant functional groups into
the polymer backbone, for instance, as part of a
polymerizable olefinically unsaturated monomer or by
substitution onto a preferred polymer by any suitable
addition reaction, e.g.:
Ol O
Polymer (C - Cl)n + n~H - O - R2 ~ C - CH2-X)
-(HCl )n 01 o
~ Polymer (C - O - R2 - C ~ CH2 - X)n
where n is an integer, and -O-R2 is R1 in expression
(1~, supra. R1 can contain heteroatoms, such as
oxygen, sulfur, phosphorus, and nitrogen, functional
groups such as carbonyl, carboxy-ester, thio, and

8 ~ 7'7~)8~
amino substltuents, and can comprise ~romatic,
olefinic or alkynyl unsaturation. Typically, Rl w111
be a cycl~c or acyclic divalent organic radical of 3
~o abou~ 40 atoms ~n length; i.e., having 3 to about
40 atoms in its shortest chain between the polymer
backbone and the interior carbonyl group~ For ease of
manufacture from readily avallable reactants~ R1 ~s
preferably of the formula:
lo 8
- C - Y - R3 - Z - (2~
wherein Y and Z are independently selected from 0, S,
and NR7~ and R3 is a divalent organ~c radical at least
1 atom in length, preferably 2 to about 40, and most
preferably 2 to about 20 atoms in length. Y and Z are
preferably 0, and R7 is H or a monovalen~ organic
radical9 pre~erably H or hydrocarbyl radical having up
to 6 carbon atoms.
~0
X in expression (1) is - C0 - R~ or
-CN, preferably - C0 - R4 where R4 is hydrogen or a
monoYalent organic radical preferably having up to 10
atoms other than hydrogen (i.e., up to 10 atoms not
counting hydrogen atoms which may be present in the
radical). Most pre~erably, R3 is selected from
substituted and unsubstituted alkylene, polyoxy-
alkylene, polythioalkylene and polyaminoalkylene
radicals, typically up to about 40 atoms in length,
preferably up to about 20 atoms in length. The
substituted and unsubstituted polythio-, polyoxy-, and
polyaminoalkylenes can be readily formed by the well
known condensation of alkylene oxides9 alkylene
amines, glycols, dia~ines, and dithiols. Thus:
/ 0\ R8
n(R8 - CH - CH2) ~O(CH2 ~ ~H2 ~ O)nH

- 9~ 77C~3
where R8 1s H or a monovalent organlc rad1cDl, prefer-
ably H or alkyl radlcal~ To 111ustrate, such pendant
~unctional groups (formula 1) can be lntroduced 1nto !,
the polymer backbone by copolymer~zation of other
monomers (discussed here~nafter) with a polymer1z~ble
monomer of the formula:
R 0
5 ll
R6 - CH = - Rl - C ~ CH2 ~ X (3)
where~n X is as defined for ~ormula 1, supra, R6 and
R5 are independently selected from hydroxy~ halo,
thio, amino, and monovalent organic radicals~ prefer-
ably having up to 10 atoms other than hydrogen~ most
preferably alkyl radicals having up to 10 carbons
atoms. Substitutlng the preferred form of the group
Rl illustrated in formula 2 for Rl in formula 1 yields
the most preferred functional monomers:
R5 01 0
6 y R3 - Z - C - CH2 ( )
where R3, R5, R6, X, Y and Z have the definitions
given above. From this expression it can be seen tha~
when R6 is hydrogen, X is - C0 - R~, R4 and R5 are
methyl, Y and Z are 0, and R3 is an ethylene radical,
the resultin~ monomer is acetoacetoxyethyl methacrylate,
- one of the class of monomers described by Smith in
U.S. Patent 3,S54,937
This monomer can be prepared by first treating ethylene
glycol with methacrylic acid to form hydroxyethyl
methacrylate which then is treated with diketene, as
described by Smith, to form acetoacetoxyethyl meth-
acrylate. A particularly preferred class of functionalmonomers~ due to their relative aYailability, are those

)83
-10-
disclosed by Smlth, whlch correspond tc ~ormula (4) in
which R6 ls hydrogen, Y ~nd Z are oxygen, R5 is
hydrogen or an alkyl group havlng up to 12 carbon
atoms~ R3 ts an alkylene group containing up to 10
carbon atoms, X is - C0 - R4, and R4 is an alkyl
group having up to 8 carbon atoms.
The useful pressure sensitive ~dhesiYe
polymers contaln a sufficient amount of one or msre of
the described functional monomers to in~rease cohesive
strength of the adhesive relative to an otherwise
identical pressure sensitive adhesive in the absence
of such functional monomers. Detectable enhancement
of cohesive strength is found in many polymers at
functional monomer concentrations as low as 0.05
weight percent. 6enerally, however, the useful
polymers will contain at least about 0.1 and typically
at least about 0.~5 weight percent of the functional
monomer based on total polymer weight. Much higher
functional monomer concentrations can be employe~.
Thus, functional monomer concentrations will usually
be between about 0.1 to about 20 weight percent or
more, typically about 0.1 to about 10 weight percent.
Surprisingly, very significant increases in cohesive
strength can be achieved at functional monomer
concentrations below 5 weight percent and even below 2
weight percent. Hence, preferred functional monomer
concentrations in many of the useful pressure
sensitive adhesives will be within the range of about
0.1 to about 5 weight percent, often within the range
of about 0.1 to about 2 weight percent.
Presently preferred polymers which contain
the above described functional monomers include (1)

~ 7 0~3
copolymers o~ subst1tuted or unsubstltuted alkenyl
aromatic monomers and con~ugated d~olef~ns, (2)
olefin ester interpolymers of C2 4 monoolef~ns and
C2 8 alkenyl or alkeno~ esters of Cl 12 saturated
carboxylic ac~ds, ~3) polymer1zed alkyl ~nd alkanol
esters of olefin~cally unsaturated carboxyl~c aclds,
~4) alkenyl ether homopolymers and lnterpo1ymers of
C2 10 olefin ethers of C1 1~ alcohols~ and (5) com-
binations thereof. In addition to the above describedfunctional monomers, each of these preferred classes
of polymers can contain additlona~ monomers such as
olefinically unsaturated mono- and polycarboxyl~c;
acids, amides, aldehydes, etc.
1~
Illustrative polymers of esters of
olefinically unsaturated carboxyl~c acids are
described by Midgley in U.S. Patent No. 4,540,739 ( 1985) .
These polymers
comprise, primari1y, one or more polymerized,
olefinically unsaturated mono- and/or polycarboxylic
acid esters, and optionally may contain other
polymerized monomers. Thus, the ester polymers
usually contain at least about 40 weight percent,
often at least about 60 weight percent, and preferably
at least about 80 weight percent polymeri2ed,
olefinically unsaturated carboxy~ic acid ester
monomers other than the above described functional
monomers. Presently preferred ester monomers are
esters of olefinically unsaturated mono- and
polycarboxylic acids having 4-17 carbon atoms, and
hydroxy-, amino-, or thio-substituted or unsu~stituted
alcohols, amines, dnd thiols having from 1 to about 30

- 1 2~ 770~3
carbon ~toms, preferably 1 to about 20 carbon atorns,
per molecule. Illustrat1vc unsaturated carboxyl1c
ac1ds are acryllc, methacryllc, fumaric~ maleic,
itaconlc, etc. Illustrative hydroxy-, am~no-, and
~hio-substituted alcohols, amines, and thiols are
glycerol, l-hydroxy-5- thiododecane, 2-amino-S~hydro-
~yhexane, etc. Presently preferred est~rs, due
pr~marily ~o cost and ava~lab11~ty, are hydroxy-
substituted and unsubstituted alcohol esters ofacrylic and methacrylic acids such a butyl acrylate,
2-ethylhexyl acrylate, methyl me~hacryla,e, hydroxy-
ethyl acrylate, etc.
A varie~y of olefinically unsaturated
carboxylic acid ester monomers, as well as a variety
of other polymerizable olefinically unsaturated
monomers useful for the manufacture of pressure
sensitive adhesive polymers, and the interrelationsh~p
of these monomers to polymer Tg tglass transition
temperature) are dlscussed in the Handbook of Pressure-
Sensitive Adhesive Technology, Yan Nostrand-Reinhold
Company, New York, 1982 particular1y at pages 298
through 329.
The principal character-
istic of pressure sensitive adhesives based on such
carboxylic acid ester homo- or interpolymers is the
low glass transition temperature (Tg) which can be
achieved, in some instances, with carboxylic acid
ester homopolymers but is usually obtained by polymer-
izing "hard" ester monomers with suitable proportions
of "soft" ester monomers to form a polymer having the
Tg best suited to the particular application. So
called "hard" monomers are those which produce homo-
polymers having relatively high Tgs, while "soft"
monomers are those which form homopotymers having
.~

- 13~ 1~7'7~33
relatiYely low Tgs. For lnstance, ~crylate monomers
are typlcally "softer" than the correspond~ng methacryl~c
acid esters. Thus, polyethyl acrylate has a Tg of
-22 C. while polyethyl methacrylate has a Tg of 65
C. The ~9 of poly-n-butyl acrylate ls -54 C. as
compared to ~ Tg of 20 C. for poly-n-butyl ~ethacrylate.
n-butyl acrylate, 2-ethylhexyl acrylate and n-octyl
acrylate are commonly employed "soft" monomers while
various methacrylates, including methyl, isopropyl,
n-butyl, and t-butyl methacrylate, are typical "hard"
monomers.
The Tg of any homopolymer can be readily
determined, and the Tg of an interpolymer of two or
more such monomers can be predicted, roughly, from the
respective T~s of each of the monomers involved. The
most exact method of determining the glass transition
temperature of the selected interpolymer of any
combination of monomers iS9 of course, measurement of
the Tg of that interpolymer per se. The homo- and
interpolymers useful in the pressure sensitive
adhesives of this invention typically have Tgs of
about 0 C. or less, preferably about -10 C. or less.
Polymers having lower Tgs are particularly preferred
for use as low temperature pressure sensitive
adhesives which generally have T~s on the order of
about -40 C. or less. Thus, the useful polymers will
generally have Tgs within the range of about _80D to
about 0 C., preferably about -60 to about -10 C.
The described functional monomers and
olefinically unsaturated carboxylic acid ester
monomers can constitute the total composition of this
polymer class, or the portion of the polymer molecule
not accounted for by those two monomer classes can be

~ ~t7~ 3
any polymeriz~ble, otefinically unsatur~ted monomer or
combinat~on of such monomers. IllustratiYe of other
poly~er~able monomers are vinyl esters of carboxylic
ac~ds, the ac~d moiety of which contains from 1 to
about 20 carbon atoms (e.g., vinyl acetate, vinyl
propionate, vinyl isononanoate); aromatic or
aliphatic, alpha beta-unsaturated hydrocarbons such as
ethylene, propylene, styrene, and vlnyl toluene; v1nyl
halides such as vinyl chloride and vinylidene
chloride; olefinically unsaturated nitriles such as
acrylonitrile; and olefinically unsaturated carboxylic
acids having up to 10 carbon atoms such as
acrylic, methacrylic~ crotonic, itaconic, and fumaric
15 acids, and the like.
The conjugated diolefin polymers typically
contain about 0. 5 to about 50 weight percent of one or
more vinyl aromatic monomers and about 50 to about 99
weight percent of one or more conjugated diolefins
having 4 to about 8 carbon atoms. These copolymers
may be either random or block interpolymers. Illus-
trative alkenyl aromatic monomers include styrene,
alpha-methylstyrene, p-methylstyrene, chlorostyrene,
methyl-bromostyrene, etc. Illustrative conjugated
diolefin monomers include butadiene~ isoprene, etc.
The alkenyl aromatic monomer is preferably present at
a concentration of about 5 to about 70 weight percent,
most preferably about 20 to about 50 weight percent,
while the conjugated diolefin monomer is typically
present at a concentration of about 30 to about 95
weight percent~ most preferably about 50 to about 80
weight percent.
As in the case of the olefinically
unsaturated carboxylic acîd ester polymers discwssed
above, the conjugated diolefin polymers can contain

~ t7~
-15-
various other monomers, in addition to the above
descrlbed functional monomers, such as the vinyl
esters of carboxylic acids, mono-olefins, olefinically
unsaturated nitriles, olefinically unsaturated
carboxylic acids~ etc., discussed above with regard ~o
the olefinically unsaturated c~rboxylic ac1d ester
interpolymers. Furthermore, the conjugated diolefin
polymers can contain up to about 40 weight percent~
typically up to about 20 weight percent, of
olefinically unsaturated carboxylic acid ester monomer
units such as those described above for use in
production of the useful carboxylic acid ester
interpolymers.
The olefin ester polymers typically contain
about 1 to about 40 weight percent of a C2 4
monoolefin monomer, from about 60 to about 99.5
weight percent of a C2 8 alkenyl or alkenol ester of a
C1 12 saturated carboxylic acid and about 0.5 to about
10 weight percent of a functional monomer as described
above. Preferably, the monoolefin monomer is present
in an amount from about 1 to 25 weight percent, most
preferably from about 10 to 15 weight percent. Illus-
2~ trative mono-olefins are ethylene, propylene and
butylene, with ethylene being preferred.
The ester component of the olefin ester
polymers is preferably a C2 8 alkenyl or alkenol ester
of a C1 12 saturated carboxylic acid. Illustrative
C2 8 unsaturated alcohols and diols which can be
reacted with C1 12 saturated carboxylic acids to form
reactive esters are C2 8 alkenols suoh as propenol,
butenol, pentenol, hexenol, heptenol and octenol and
their diol homologues. Suitable saturated acids
include formic, acetic, propionic, butanoic, valeric,
caproic, heptanoic and octenoic acids~

! !
~ 1 6~ 70t33
The most common of the foregoing esters are v~nyl
acetate, v~nyl proploniate, and vinyl butanoate.
The alkenyl ether polymers ~ypically conta~n
at least about 30 weight percent, preferably at least
about 50 weight percent~ polymerized alkenyl ether
mono~er units in which the alkenyl group has at least
2 carbon atoms, typically 2 to about 10 carbon atoms,
and the alcohol (hydrocarbyl-oxy) group has from 1 to
a~out 10 carbon atoms. Illustrative are methylvinyl
ether, n-octyl-1- propenyl ether, 2,4-dimethylbutyl-2
-hexenyl ether, vinylphenyl ether, etc.
The polymers encompassed by the four general
classes described above can contain minor amounts,
e.g. up to 30 weight percent, of one or more
additional monomers, and they can be grafted or
reacted with other chemical agents to modi~y their
che~ical composition. Thus, the polymers of groups
~1) and (3) may contain minor amounts of substituted
and unsubstituted monoolefin monomers such as
ethylene, isobutylene, chlorobutenes, acrylonitrile,
vinyl ethers, alkenyl esters of saturated carboxylic
acids, etc. The conjugated diolefin polymers (group
1) may also contain olefinically unsaturated
carboxylic acid ester monomers, and the olefinically
unsaturate~ acid ester polymers (group 3) may contain
conjugated diolefin and/or alkenyl monoaromatic
monomers. Similarly, the alkenyl ester polymers of
group (2) and the alkenyl ether polymers of group (4)
can contain substituted and/or unsubstituted
conJugated diolefins, alkenyl aromatics, olefinically
unsaturated carboxylic acid esters, etc.
It has been found that minor amounts of
olefinically unsaturated mono- and polybasic carboxylic

83
~17-
ac~ds and/or sulfoalkyl esters of such carboxylic
acids significantly improve cohesive strength of the
PSA polymers. Thus, it is presently preferred that
the polymers contain at least about 0.1 weight percent,
usually about 0.1 to about 10 weight percent, and
preferably about 0.1 to about 5 weight percent of a
polymerizable, olefinically unsaturated carboxylic
acid having up to about 10 carbon atoms and/or a
1~ sulfoalkyl este~s of such acids~ e.g. sulfoethyl
methacrylate, sulfoethyl itaconate~ sulfo~e~hyl
malonate, etc.
Although the polymers can contain other
"functional" monomers such as N-methylol amides, e.g.,
N-methylol acrylamide, it has been found that such
other functional monomers are not essential to
achieving acceptable adhesive properties and that the
detriment associated with the presence of such
mcnomers, such as formaldehyde release upon curing,
loss of tack and adhesion, etc., can be avoided by
minimizing the concentration of such N-methylol amides
or eliminating them altogether. Thus, the preferred
polymers contain less than about 1 percent, preferably
less ~han about 0.5 percent, and mos~ preferably no
amount of N-methylol amide monomer units.
It also has been found that suitable
adhesive properties can be achieved without
crosslinking or hardening agents such as aldehyde
hardeners (e.g., formaldehyde, mucochloric acid,
etc.~, crosslinking catalysts such as the strong base
catalysts discussed by Bartman in U.S. Patent
4,408,018, acid catalysts such as phosphoric or
; 35 methane sulfonic acid, complexing agents such as
metals and metal compounds and complexes, or reactive
monomers (e.g., glycols, polyamides, etc.). Since

~7~ 3
- 1 8 -
such hardening 3gents ~ncrease the complexlty and
expense of polymer manufacture9 they are not requ~red
to obtain the necessary pressure sensitive propert~2s
with the polymers o~ this invention, and~ in many
instances, the lncorporation of such "harden~ng"
agents impairs other desirable PSA properties such as
tack and adhesion, the preferred polymers are
substantially free of such hardening agents or their
residues. Nevertheless, minor amounts of such
materials can be present.
Polymer molecular weight can have a
significant effect on the balance of pressure
sensitive adhesive properties in polymers of a given
rnonomer cDmposition, i.e. polymers of identical
monomer content. Thus, as discussed in the Handbook
of Pressure Sensitive Adhesive Technology, for
instance at pages 307-311, shear resistance is roughly
proportional to molecular weight up to relatively high
molecular weights at which shear resistance drops off
dramatically in some polymers. Tack is typically high
at very low molecular weights and decreases gradually
as molecular weight is increased after a molecular
weight value yielding optimum tack is exceeded.
Adhesion typically exhibits discontinuous behavior,
increasing with molecular weight up to moderate
molecular weight levels and then gradually decreasing
as molecular weight is increased further. The
polymers useful in the adhesives of this ~nvention
typically have number average molecular weights of at
least about 10,000, generally within the range of
about 10,000 to about 1,000,000 as determined by gel
permeation chromatography. Such polymers have
relatively hi~h shear values and a favorable balance
of other properties including peel value and tack.
Thus, the adhesives typically have shear holding

7~)a3
- 1 g -
values of at least about 20 minutes, typically at
leas~ about 50 min tes, and, in high shear formulat10ns,
as much as 19000 minut~s or more measured at 75 F.
under 500 gram loading as described hereinafter. Peel
values are generally at least about 1.5, most o~ten at
least about 1.8, and preferably at 1east about 2
pounds per inch width. Yet the hlgh shear and peel
values of these pressure sens~tive adhesives are not
achieved at the expense of significant, if any, loss
o~ tack. Thus, the polymers generally have loop tack
values of at least abou~ 0.8. pounds per half inch
width, i,e., they exhibit loop tack approximately
equivalent to, and sometimes even higher than, the
loop tack exhibited by otherwise identical polymers
not containing the described functional monomers under
otherwise identical conditions (monomer content,
molecular weight, etc.) For the purposes of this
disclosure, shear strength, peel adhesion, and loop
tack are determined as described hereinafter in the
illustrative examples unless otherwise specified.
Many of the polymers useful in this
invention exhibit sufficient tack for many PSA
applications without added tackifiers, although the
conjugated diolefin polymers generally require
tackifiers to posses tack sufficient for many
applications. Illustrative of polymers which are
usuàlly employed with tackifiers are conjugated
diolefin polymers and their interpolymers, such as
polymers and interpolymers of isoprene, butadiene,
etc. in the presence or absence of other monomers,
e.g. styrene. On the other hand, the polyalkenyl
ether and olefinically unsaturated carboxylic acid
ester polymers, and interpolymers of olefins and
alkenyl carboxy7ic acid esters usually exhibit

t7()~33
-20-
sufflc~ent tack~ 1n the absence of tackifiers, to be
useful as pr~ssure sensitive adhesiYes. Nevertheless,
adhesives based on such polymers also may contain
5 compatible tackifiers to provide increased ~ack ~f
des i red .
The adhesives may contain very minor
amounts of tackifiers to increase tack on1y slightly,
or they may contain up to 150 weight parts or more of
tackifier per 100 weight parts of one or more of the
described polymers. Suitable tackiFiers include
rosins, hydrogenated rosins, esters of such rosins,
synthetic hydrocarbon tacki~iers and low molecular
weight and low Tg polycarboxylic acid esters. Typical
rosins and hydrogenated rosin ester tackifiers have
ring and ball softening temperatures of about 25 C.
to about 115 C., while preferred tackifiers have
softening temperatures of about 50 C. to about 110
C. Useful hydrocarbon tackifiers may be manufactured
from C9 aromatic monomers or from C5 aliphatic monomers
and mixtures of such aromatic and aliphatic monomers.
Such monomers are usually derived from the so called
Cg and C5 cuts in the fractîonation of crude oil or
similar material. Such -synthetic hydrocarbon tackifiers
generally have ring and ball softening temperatures of
about 10 C. to about 100 C. The polycarboxylic acid
ester tackifier resins are polymerized from ore or
more monomers such as acrylic acid which is substituted
or unsubstituted with alkyl or alkoxyl radicals having
one to four carbon atoms or with alkyl or alkanol
esters of such acids in which the alkyl or alkanol
moiety has from one to about six carbon atoms.
~he useful polymers can be prepared by free
radical solution and emulsion polymerizat;on methods

~7~7(3~33
-21-
known in the ar~ ~ncludlng batch, cont~nuous andsemicontinuous procedures. For the purposes of this
d~sclosure, free rad~cal polymerizat~on methods are
5 ~ntended to include radiation polymerization techniques.
Illustrative free-radical polymerization procedures
suitable for preparing aqueous polymer emulsions
involve gradually adding the monomer or monomers to be
polymerized simultaneously to an aqueous reaction
1~ medium at rates proportionate to the respective
percentage of each monomer in the finished polymer and
initiating and continuing polymerization with a
suitable free radical polymerization catalyst.
Optionally, copolymers can be obtained by adding one
or more comonomers disproportionately throughout the
polymerization so that the portions of the polymers
formed during the initial polymerization stage
comprise a monomer composition differing from that
formed during intermediate or later stages of the same
polymerization. For instance, a styrene-butadiene
copolymer can be formed by adding a greater proportion
or all of the styrene during the initial polymerization
stages with the greater proportion of the butadiene
being added later in the polymerization.
Illustrative free-radical catalysts are free
radical initiators such as hydrogen peroxide, potassium
or ammonium peroxydisulfate, dibenzoyl peroxide, lauroyl
peroxide, ditertiarybutyl peroxide, 2,2'-azobis-
isobutyronitrile, etc., either alone or together withone or more reducing components such as sodium bisul-
fite~ sodium me~abisulfite, glucose, ascorbic acid,
erythorbic acid, etc. Ultrav;olet ~UV) and electron
beam polymerization methods suitable for initiating
free radical polymerization are discussed in the
Handbook of Pressure-Sensitive Adhesive Technology,

70~33
-22-
partlcularly at pag2s 586-604 and the references c~ted
therein. The reaction is continued w1th ag1tat1On at a
temperature suff~clent to maintain an adequate
reactlon rate unti1 most or all monomers are consumed.
Mono~er addition is usually contlnued unt11 the latex
reaches a polymer concentration of ~bout 20 to about
70 wei~ht percent.
Physical stability of the dispersion usually
is achieved by providing ln the aqueous reaction
medium one or more nonlonic, anionic, and/or amphoteric
surfactants including copolymerizable surfactants such
as sulfonated alkylphenol polyalkyleneoxy maleate and
copolymerizable stabilizers such as sulfoethyl meth-
acrylate, alkenyl sulfonates, etc.~ I11ustrative of
nonionic surfactants are alkylpolyglycol ethers such
as ethoxylation products of lauryl, oleyl, and stearyl
alcohols or mixtures of such alcohols as coconut fatty
alcohols; alkylphenol p~lyglycol ethers such as ethoxyla-
tion products o~ octyl- or nonylphenol, diisopropylphenol,
triisopropylphenol, di- or tritertiarybutyl phenol,
etc. Illustrative of anionic surfactants are alkali
metal or ammonium salts of ~lkyl, aryl, or alkylaryl
sulfonates, sulfates, phosphates, phosphonates, etc.
Examples include sodium lauryl sulfate, sodium octyl-
phenol glycolether sulfate, sodium dodecylbenzene
sulfonate9 sodium lauryldiglycol sulfate, and ammonium
tritertiarybutylphenol penta- and octa-glycol sulfates.
Numerous other examples of suitable ionic, nonionic
and ~mphoteric surfactants are disclosed in U.5.
Patents 2,600,831, 2,271,622, 2,271,623, 2,275,727,
2,787,604, 2,816,920, and 2,739,891.
Protective colloids may be added to the
aqueous polymer dispersions either during or .fter the

7 ~3
-23-
reaction per~od. Illustrat~ve protect~ve colloids
include gum arablc, starch, alginates, and modified
natural substances such as methyl-, ethyl-, hydroxyalkyl-,
and carboxymethylcellulose, and synthetic substances
such as polyvinyl alcohol, polyvinyl pyrrolidone, and
mixtures of two or more o~ such substances. F~llers
and/or extenders such as d~spersible clays, and
colorants, such as pigments and dyes, can also be
added to the aqueous dispersions either during or
after polymerization. Those skilled in the art of
emulsion polymers will appreciate that protective
colloids9 tackifiers, and other additives should be
compatible with the polymer emulsion to assure
formation of a stable dispersion.
The emulsions typically contain about 20 to
about 70 percent polymer as manufactured, while
preferred latexes typically have solids contents of
about 40 to about 60 weight percent polymer solids.
The dispersed polymer particles can be of any size
suitable for the intended use, although particle sizes
of at least about 100 nanometers are presently
preferred. Most often, the described latexes will
have particle sizes within the range of about 100 to
about 1000 nanometers as determined on the model N-4
or the "Nanosizer" available from Coulter Electronics,
Inc., of Hialeah~ Florida.
Solutions of the useful polymers can be
prepared by polymerizing the selected monomers as
described above in solvents in which both ~he monomers
and the polymers are soluble. Suita~le solvents
include aromatic solvents such as xylene and toluene,
alkanes such as hexane, and alcohols such as butanol.
Polymerization initiators and reducing components,
when employed, should be soluble in the selected

7'70~33
-2q-
solvent or mixture of solvents. Illustrative free
radical initiators soluble in the noted organic
solvents include dibenzoyl peroxide, lauroyl peroxide,
and 2,2'-azobislsobutyronitrile. Erythorblc and
ascorbic acids are illustrative of reducing components
soluble In polar organic solvents.
Hot melt adhesives containing the described
polymers can be obtained by procedures and with form-
ulations known in the art to be suitable for the form-
ulation of pressure sensitive adhesives of such
polymers which do not contain the described functional
monomers. For instance, the useful polymers can be
separated from their solutions by evaporation of the
solvent; and they can be separated from water based
emulsions by evaporation of water, coagulation with
strong acids and/or multivalent metal ions~ e.g.
calcium, aluminum, magnesium, etc, or by subjecting
the emulsion to one or more freeze-thaw cycles. The
coagulated polymer is then filtered from the aqueous
phase and dried prior to compounding~
Typically, the compounded hot melt adhesives
will contain about 10 to about 98 weight percent,
generally about 15 to about 90 weight percent of one
or more of the described polymers in the presence or
absence of other polymers, tackifiers, antioxidants,
wa~es or oils and optional additives such as colorants
and fillers. The higher polymer concentrations wîthin
these ranges generally are employed only with polymers
which themselves ~re normally tacky~ such as the homo-
polymers and copolymers of olefinically unsaturated
carboxylic acid esters, ole~in-alkenyl carboxylate
copoly~ers~ and alkenyl ether polymers. Other of the
useful polymers which are no~ normally tacky, and
which therefore require significant amounts of tacki-

~770~3
- 2 s ~
fiers, are usually employed dt lower concentrations of
about 10 to ~bout 60, generally about 15 to about 50
weight percent; the remainder of the hot melt formu
lation comprising t~ckifiers in the presence or
absence of other addit~ves9 e.g. ant~ox~dants, wa~es~
oils, fillers, etc. The use of waxes and o11s in the
described adhesives usually is undesirable due to the
detrimental effects such materials may have on adhesive
tack. Howevert small amounts of such materials can be
employed, usually to reduce melt viscos~ty. Those
skilled in the art of pressure sensitive adhesives
will, of course, recognize that the tackifier or
tackifiers, when employed, should be compatible with
the selected polymer or polymers to ensure homogenity
in the final hot melt formulation.
The hot melt adhesives can be compounded by
mixing the selected polymer or polymers, antioxidants
and optionally fillers in a jacketed mixing kettle,
such as a heavy duty mixer of the Baker-Perkins or Day
mixer type, equipped with rotors and operated at
temperatures of about 200 to about 350 F., the
precise temperature employed depending on the melting
point of the polymers selected. After complete melting
has occurred, the tackifiers are added and mixing is
continued. Waxes and/or oils, when employed, are
usually added toward the end of the mixing cycle after
which mixing is continued until a smooth, homogeneous
composition is obtained. The resulting hot melt
composition can be drawn off and used im~ediately in
hot pots, or it may be shaped or cast into any desired
form for a later use.
The pressure sensitive adhesives can be
applied to any backing which it is desired to adhere
to another surface or article. Illustrative backings

~ 3
-26-
~nclude flexlble and r~g~d, natural ~nd synthet1c
~ater~als such as plast~cs, elastomers. solld metals
and foils, ceramlcs (tlles, glass~ etc.), wood, papers
and cardboard, leather mater~als, etc. of essent1~11y
any for~ ~ncludlng films, solld artfcles, woven and
non-woven textile mater~als, etc. Illustrat~ve uses
of such articles ~nclude wal1 coverings (paper, ~abr~c,
films, etc.), upholstery ite~s, constructlon roo~ing
and siding materials, tapes of al1 varieties ~includ~ng
those having backings comprised of woven or non-woven
~abrics9 paper9 polymeric films, metal foils~ foams,
etc., including doub1e ~aced tapes and so called
transfer tapes), packaging, floor and wall tile and
other floor and wall cover~ngs, panel~ng, etc.
Suitable backinq and substrate materials can be of
essentially any chemical composition and Include
metals. ceramics (including all varieties of glass),
and natural and synthetic polar and non-polar materials
such as polyolefins, e.g. homopolymers and ~nterpolymers
of substituted and nonsubstituted olefinically unsaturated
hydrocarbons including ethylene, propylene, styrene,
butadiene, dicyclopentadiene, etc., and materials
which typically contain polar functional groups such
as hydroxy, etheral, carbonyl, carboxylic acid (including
carboxylic acid salts), carboxylic acid esters (including
thio esters), amides, amines, etc. Essentially all
natural materials include one or more polar functional
groùps. Illustrative are virgin and reclaimed cellulosic
fibers such as cotton, paper, wood, coconut fiber, jute,
hemp~ etc., and protenaceous materials such as leather,
wool, and other animal fur~ IllustratiYe synthetic
materials containing polar functional groups are
polyesters, polyamides, carboxylated styrene-butadiene
polymers, etc., such as Nylon-6, Hylon-66, Nylon-610,
"Dacro*n'', "Fortrel"? "Kodel", "Acrilan~9 "Orlon~', "Creslan"p
"Verel" and "Dynel". Illustra~ive o~ other use~ul
Trademark

1 ~d~7~383
-27-
polar materials are synthetic carbon, silicon, and
magnes~um sllica~e (e.g., asbestos).
The adhesive compositions may be applied tu
the backing by any one of a variety of conventional
coating ~echniques such as roll coating, spray
coating, curtain coating, etc. They also may be
applied to the backing without modification by
extrusion coating, coextrusion, hot melt coating,
etc., by employing suitable conventional coating
devices known for such coating methods. While primers
may be employed to pretreat the backinq, they are
unnecessary in many applica~ions. Dry coating weight
(the weight of dry adhesive applied per unit surface
area) can vary substantially depending upon the
porosity and irregularity of the backing and of the
substrate surface to which the backing is to be
adhered, and other factors. For instance~ higher
polymer loadings are preferred for adhering porous,
irregular ceramic tiles to porous surfaces, while
lower adhesive loadings are usually required to
manufacture tapes, films, and other articles from
relatively non-porous, smooth-surfaced materials such
as synthetic polymer films and sheets. When the
adhesive is applied to non-porous polymeric or metallic
substrates intended for adhesion to non-porous polymeric
or metallic surfaces, adhesive loadings of about 5 to
about 50 pounds of dry adhesive per 3,000 square feet
of treated surface are generally adequate. Adequate
adhesion in tapes manufactured from continuous sheet
polymeric substrates can usually be achieved with dry
coa~ing adhesive weights of about 10 ~o about 20
pounds per 3,000 square feet o~ treated surface, while
coating weights of 20 to about 40 pounds per 3,000
square feet are usually employed for paper-backed
tapes such as masking tapes.

~77~)83
- 2 ~ -
The invention Is further described by the
following ~xanlples which are illustrative of specific
modes of practic~ny ~he invention and are not intended
as limlting the scope of the invention as defined by
the appended claims.
TEST STANDARDS
. _
Test samples are prepared by applying to a
1-mil mylar backing a film of adhesive latex, solution
or melt which, when cured, forms a 1-mil adhesive
layer. Hot melts are applied hot, drawn down to about
1-~il films and cooled. Solution polymers are applied
15 in somewhat thicker layers and oven dried for a peri~d
sufficient to evaporate the solvent. Emulsion
polymers are also appl ied in layers slightly thicker
than 1-mil and are dried at 150 F. for 20 minutes,
covered with a release liner and aged 24 hours at 73
F. and 50 percent relative humidity.
Shear strength is determined in accordance
with ASTM D3654 78, PSTC-7 and is a measure of the
cohesiveness (internal strength) of an adhesive.
~"PSTC" designates the Pressure SensitiYe Tape Council)
It is based on the time required for a static loaded
tape sample to separate from a standard flat surface
in a direction essentially parallel to the surface to
whi~ch it has been affixed with a standard pressure.
Each test is conducted on an adhesive coated strip
applied to a standard stainless steel panel in a
manner such that a one-half ineh by one-half inch
portion of the strip is in firm contact ~ith the panel
with one end portion of the strip being free. The
steel panel, with coated strip attached, is held in a
rack such that the panel forms an angle of 178 to
180 with the extended tape free end which is then

7~)~3
-29-
tens~oned by appl~cat~on of a force of 500 grams
appl~ed ~s ~ hang~ng weight from the free end of the
test strip. The elapsed t~me required for each test
strip to separate from the test pane1 at 73~ F ~s
recorded ~s shear s~rength.
Peel adhesion is determined in accordance
with ASTM ~-3330-78, PSTC-1 and ~s a measure of the
I0 force required to remove a coated, flexible sheet
material fro~ a test panel at a speeific angle and
rate of remova1. Unless otherwise specified, the
values for peel adhesion reported hereln are force
values expressed as pounds per inch width of coated
~est sheet mater~al determ~ned at 73 F. by the
following procedure, A one-~nch width of the coated
sheet is applied to a horizontal surface of a clean,
stainless steel test plate with at least five lineal
inches of the coated sheet material in firm contact
with the steel plate. A hard rubber roller is used to
firmly apply the strip and remove a71 discontlnui~ies
and entrapped air. The free end of the coated strip
is then doubled back nearly touching itself so that
the angle of removal of the strip from the steel plate
will be 180. The free end of the test strip (the one
pulled) is attached to the adhesion tester scale (an
Instron tensile tester or Harvey tensile tester). The
test plate is then clamped in the jaws of the tensile
tes`ting machine capable of moving the plate away from
the scale at a constant rate of 12 inches per minute.
The scale reading in pounds is recorded as the tape is
peeled from the steel surface.
Loop tack is a measure of the force required
to remove a standard adhesive coated Mylar film loop
from a standard ~P5TC) stainless steel plate at 73 F.
after only nominal contact of the test strlp with the
Txademark

~ t~3
-39-
steel plate ~n the absence of s~gn~ficant pressure. A
one-half by four-~nch strip of one mil Mylar film
coat2d with the sa~ple adhesive ls formed into a loop
with the adhes~ve side out, and the loop is appl~ed to
a stainless steel plate until the tape loop contac~s
0O5 square inch of surface area on the pla~e. The
loop is retracted from the plate at a rate of 12
inches per minute, and loop tack is defined as the
force observed when the final portion of the adhesive
strip separates from the test plate. Specifically,
the steel test plate is inserted in the 70wer jaws of
an Instron tensile tester while the upper portion of
the loop is clamped in ~he upper jaw of the ~ester and
is moved downward toward the test plate at a rate of
12 inches per minute~ When the ~est loop has contacted
0.5 square inch of te~t plate area, the direction of
travel of the upper jaw of the Instron tester is
reversed and set to remove the loop from the plate at
a rate of 12 lineal inches per minute.
"Twenty degree hold strength to corrugated
board" is a measure of combined peel and shear strength
of the adhesive mounted on 1-mil Mylar film when
applied under standard force to a corrugated cardboard
substrate. Samples of adhesive coated Mylar are
applied to a standard corrugated cardboard substrate
such that a one and one-half inch length of the
adhesive coated film adheres to the corrugated surface
of the test substrate with the one and one-half inch
edge of the sample tape aligned parallel to the
corrugated flutes (ridges) of the substrate. After
application of the film to the substrate in this
manner, the film portion contacting the substrate is
rol1ed down with a standard four and one-half pound
rubber-covered roller one time parallel to the one and
one-half inch edse cf the test tape at a roller spe~d

77~)83
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of 12 ~nches per minute. The sa~ple i5 then mounted
in a shear test block set at an angle of 20 to the
vertical so that the ~tai1" of the adhesive test strip
(the portiDn of the test tape not adhered to the
corrugated substrate) is hanging down from the bottom
portion of the corrugated board at an angle of 160 to
the plane of the corrugated board. A 500 gram weight
is then affixed by appropriate clamps to the "tail
end" of the test strip so that the weight is hanging
at an angle of 160 from the portion of the test strip
bonded to the corrugated board. A timer ~s started
immediately upon application of the 500 gram weight to
the test strip, and hold value is reported as the
number of minutes required for the weight to tear the
test strip from the corrugated backing at a
temperature of 73 F.
EXAMPLE 1
A water based emulsion of an acrylate
polymer containing 98.5 weight percent butyl acrylate
and 1.5 weight percent methacrylic acid can be
prepared by free radical polymerization of the
premixed monomers in the presence of water, surfactants
and catalysts in an agitated reactor. The monomer
premixture is ~ormed by blending 862 grams butyl
acrylate, 13 grams methacrylic acid, and 0.1 gram of
chain transfer agent. The catalyst premixture can be
formed by dissolving 4.0 grams of sodium persulfate in
114 grams deionized water, and the reactor is then
charged with 690 grams deionized water~ 20 grams of an
alkylphenoxy poly(ethyleneoxy) ethanol surfactantD 2.5
grams of a sodium alkyl sulfonate surfactant, and 50
grams of the monomer ~remixture. This reactor charge
is then heated to 90 C., 10 ml. of catalyst solution
is added, and the resulting mixture is agitated for 10

~'7~ 0~3
-32-
mlnutes. Monomer prem~xture and catalyst solution
additions are then commenced. Eight hundred ninety
ml. of the monomer premixture is added over a period
of 2 hours, and the total catalyst solut~on ~s added
over a period of 2.5 hours. Thus, catalyst add~t~on
is continued for one-half hour aft~r mono~er addition
is discontinued. After catalyst addition is discon-
tinued, the reaction phase is maintained at 90 C. for
an additional 1 hour, is then cooled to 35~ C. and
removed from the reactor. The pH can be adjusted to
7.5 to 8.0 with ammonium hydroxide.
EXAMPLE 2
The operation described in Example l can be
repeated employing identical reactor feed materials
and operating procedures with the exception that the
monomer premixture contains 887 grams butylacrylate,
13.7 grams methacrylic acid9 and 18.4 grams of aceto-
acetoxyethyl methacrylate (AAEMA) correspondin~ to a
finished polymer composition of 96.5 weight percent
butylacrylate, 1.5 weight percent methacrylic acid,
and 2.0 weight percent AAEMA.
The polymers of Examples 1 and 2 will
exhibit am~ient and low temperature peel, tack, and
shear values characteristic of low temperature pressure
sensitive adhesives. However, the polymer of Example
2, containing 2 weight percent acetoacetoxye~hyl
methacrylate, will possess a substantially higher
shear value than the polymer of Example 1 and room
temperature tack comparable to that of the polymer of
Example 1. The adhesive of Example 2 will evidence
much less tendency to be gummy and therefore unmanageable,
to creep9 or to bleed-through adhesive backings or
substrates at ambient temperatures than will the
polymer of Example l.

~77()83
- 3 3 -
EXAMPLE 3
To a 2-liter reactor equ~pped w~th heating
mantle, mechanical s~irrer, reflux condenser, n~trogen
sparge and three laboratory meter~ng pumps are added
140 grams of distilled water9 and the water ls sparged
with nitrogen and heated to 75 C. The n1trogen
sparge is then removed and a nitrogen atmosphere is
maintained over the liquid phase~
A monomer pre-emulsion is formed by blending
426 grams of 2-ethylhexyl acrylate, 162 grams methyl
acrylate, 12 grams of acrylic acid~ 9 grams of nonyl-
phenoxy poly(ethyleneoxy)ethanol nonionic water-soluble
surfactant, and 21 grams of ~ctylphenoxy poly(ethylene-
oxy)ethanol nonionic surfactant in l40 grams of distilled
water. Five percent of this pre-emulsion is introduced
to the reactor with agitation. After stirring for 3
minutes, 0.5 gram of sodium persulphate dissolved in
10 grams of distilled water is added. A~ter a further
3 minutes, 0.5 gram of sodium metabisulfite is added,
and the mixture is held at 75~ C., for 20 minutes.
The remainder of the monomer pre-emulsion is then
added gradually over a period of 3 hours through one
of the metering pumps provided. The catalyst solutions
are added through the two remaining metering pumps and
concurrently with monomer emulsion addition. One
catàlyst solution contains 1.5 grams of sodium persulphate
dissolved in 75 grams of distilled water) and the
other contains 1.5 grams of sodium metabisulphite
dissolved in 75 grams of distilled water. These
catalyst solutions are added gradually at a rate such
that they are metered into the reactor o~er a period
of 3.5 hours. Monomer addition is discontinued 1/2
hour before catalyst addition is discontinued, and
polymerization temperature is maintained at 75~ C.

383
- 3 4 -
throughout the run. After all of the sodium persulphate
and sod~um metabisulphite solutions have been added,
the reaction mixture is held for an additional 30
minutes at 75 C. and is then cooled to rosm temperature~
The resulting latex is neutral ized to a pH between 4
and 6.5 with either 7 percent ammonia or 10 percent
sodium hydroxide in distilled water. The resulting
latex is tested by the procedures described above and
is found to have a peel value of 6 pounds and evidences
cohesive failure, a loop tack of 1.3 pounds, and a
shear value of 100 minutes. Cohesive failure is
evidenced by tearing or separation of the adhesive
itself, with the separated portions of the adhesive
remaining adhered to their respective substrates.
These results are summari~ed in Table 2 which follows
Example 5.
EXAMPLE 4
The operation described in Example 3 is
repeated with the exception that the monomer
pre-emulsion contains 426 grams 2-ethylhexyl acrylate,
156 grams methyl acrylate, 12 grams acrylic acid, and
6 grams o~ acetoacetoxyethyl methacrylate ~AAEMA).
Surfactant compositions and operating procedures are
as defined in Example 3.
The resulting latex is tested by the procedures
described above and has a peel value 3.~ pounds per
inch width (evidencing adhesive faiJlure) 9 a loop tack
of 1.2 pounds per 1/2 inch width, and a shear value of
186 minu~es. Although this adhesive has a peel
strength lower than that obtained in Example 3, its
loop tack is essentially equivalent, and its shear
strength is substantially higher. These results are
summarized in Table 2.

-35-
EXAMPLE 5
The operation descr~bed 1n Example 3 is
again repea~ed with ~he exseption ~hat the monomer
pre-emulsion contains 426 grams of 2-ethylhexyl
acrylate, 150 grams methyl acrylate, 12 grants acrylic
acid, and 12 grams AAEMA. Surfactant compos1tion and
concentration and op~rating conditions are otherwise
as defined in Example 3.
This product ~s tes~ed by the procedures de-
scribed above and has a peel value of 2.6 pounds per
inch width (evidencing adhesive failurè), a loop tack
of 1.1 pounds per 1~2 inch width and a shear value of
1,866 minutes. These results demonstrate an l8-fold
increase in shear value over the adhesive of Examp1e 3
with little or no loss in loop tack.
TA8LE_2
MONOMERS~ ~
Ex.No. 2-EHA MA AA AAEMA PEEL TACK SHEAR
. . .
3 71 27 2 0 6 1.3lOO
4 71 26 2 1 3.2 1.2186
71 25 2 2 2.6 l.l1,866
EXAMPLE 6
A latex can be prepared by the procedures
described in Example 3 employing a monomer pre-emulsion
containing 582 grams (97 weight percent~ butyl acrylate,
18 grams (3 weight percent) acrylic acid, 0.1 weight
percent of a sodium salt of sulphated nony1phenoxy
poly(ethyleneoxy)ethanol surfactant, and 1.5 weight
percent of the octyl phenoxy sur~actant described in
Example 3.

~77
-36-
EXAMP E 7
The operation descr~bed in Example 6 car be
repea~ed with the exception that the msnomer compositiDn
in the pre-emulsion contains 576 grams (96 weight
percent) butyl acrylate, 18 grams (3 weight percent)
acrylic acid, and 6 grams (1 weight percent) AAEMA
with all other compositions and operating conditions
remaining the same. The resulting adhesive will have
significantly higher shear strength than will the
adhesive of Example 6 with little or no loss of tack.
EXAMP~E 8
The operation of Example 6 can be repeated
employing a monomer pre-emulsion contai ni ng 582 grams
2-ethylhexyl acrylate and 18 grams acrylic acid corre-
sponding to a polymer composition of 97 weight percent
2-ethyl hexylacrylate and 3 weight percent acrylic
acid, with surfactant compos~tions and operating
conditions otherwise remaining the same.
EXAMPLE 9
The operation described in Example 6 can be
repeated with the exception that the monomer content
of the monomer pre-emulsion corresponds to 576 grams
2-ethylhexyl acrylate, 18 grams acrylic acid and 6
grams AAEMA resulting in a polymer containing 96
weight percent 2-ethylhexyl acrylate, 3 weight percent
acrylic acid, and 1 weight percent AAEMA. This
polymer will have significantly higher shear than the
polymer obtained in Example 8 with little or no loss
in tack.

~3
-37-
EXAMPLE 10
The operation described in Example 6 can be
repeated with a monomer pre-emulsion having a monomer
content of 291 grams butyl acrylate, 2g1 grams 2-ekhyl~
hexyl acrylate, and 18 grams acryl~c acid corresponding
to a polymer compositior of 48.5 we~ght percent butyl-
acrylate, 48.5 weight percent 2-ethylhexyl acrylate,
and 3 weight percent acrylic acid.
EXAMPLE 11
The operation described in Example 6 can be
repeated employing otherwise identical compositions
and conditions with the exceptinn that the monomer
pre-emulsion contains 288 grams butyl acrylate, 288
grams 2-ethylhexyl acrylate, 18 grams acrylic acid~
and 6 grams AAEMA corresponding to a polymer com-
position of 48 weight percent butyl acrylate, 48
weight percent 2-ethylhexyl acrylate, 3 weight percent
acrylic acid, and 1 weight percent AAEMA. The result-
ing polymer will have significantly higher shear than
the polymer of Example 10 with little or no loss of
tack.
EXAMPLE 12
An N-methylolacrylamide-containing polymer
can be obtained by the procedure described in Example
6 with the exception that the monomer pre-emulsion
contains 288 grams butyl acrylate, 288 grams
2-ethylhexyl acrylate, 18 grams acrylic acid and 6
grams ~-methylolacrylamide with all other operating
condi~ions and surfactant composi~ions being the same
as described in ~xample 6. The resulting polymer witl

7 ~ 3
-38-
con~in 48 ~e19ht percent butyl acrylate, 4~ we1ght
percent 2-ethylhexyl 3crylate, 3 weight percent
acrylic acid, and 1 weight percent H-methylolacrylamide.
Th~s polymer will have s~gn~cantly h1gher cohes~ve
(shear) strength than the polymer descrfbed ~n Example
10 and peel and tack values substantially lower th~n
the peel and tack values of the polymer obta1ned in
Exa~ple 11.
EXAMPLE 13
. .
A styrene--butadiene-acrylic acid polymer can
be prepared by adding to a pressure reaceor 67 we~gh~
parts water, 8.3 weight parts Polystep RA 35 S surfactant
~thc sodium salt of a sulfonated nony1phenol polye~hyl-
eneoxy maleate available from Stepan Chem~cal Company,
Northfield, Illinois), 2.5 weight parts acrylic acid,
0.2 weight parts tetrapo~assium pyrophosphate and 0.83
weight parts sodlum hydroxide with continuous agitation.
2 weight parts dodecyl mercaptan dissolved ~n 30
weight parts styrene is added, and 67.5 weight parts
butadiene is then introduced. Reaction is initiated
by introduction of 8.3 weight parts of a 4 weight
percent solution of potassium persulfate, reactor
temperature is brought to 100 F., 0.002 9. sodium
ferric ethylenediamine tetracetate i5 added, and
polymerization is continued for 1 hour dt 100 to 115
F. Reaction temperature is then incrementally increased
over the next 6 hours to 155 F., and polymerization
is continued at that temperature for an additional 24
hours. 50 weight parts of the resulting polymer latex
(dry weight) is then blended with 50 weight parts (dry
weight) of an aqueous emulsion of Burez Stabilized
Ester 85, a pentaerythritol ester of dispropor-
tionated rosin available from Tenneco Malrose Ltd.,
Rocklngham ~orks, Avonmouth, Bristot, Engl~nd. The
Trademark

7 ~ 83
-39-
peel, shear, 700p tack and corrug~ted hold values for
this adhesive can be determined by the prosedures
discussed above.
EXAMPLE 14
The procedure described in Example 13 can be
repeated with the exceptlon that 2 weight parts AAEMA
is added to the polymerization mixture along with the
butadiene. Reaction conditions, polymer eomposition
and tackifier blending are otherwise as described in
Example 13. The peel, shear, loop tack and corrugated
hold values for the product can be determined by the
procedures discussed above, and it will be found to
have significantly higher shear and a~ least comparable
or higher peel, loop tack and corrugated hold values
in comparison to the polymer of Example 13.
EXAMPLE 15
The operation described in Example 13 can be
repeated using a monomer mixture containing 30 weight
parts styrene, 69 weight parts butadiene and 1 weigh~
part itaconic acid, with all other conditions and
compositions remaining the same. The resulting latex
can be blended with tackifier emulsion as described
in Example 13, and strength values can be determined
as described above.
EXAMPLE 16
The operation described in Example 15 can be
repeated with the exception that 1 weight part AAEMA
is added to the monomer mixture along with the butadiene.
When evaluated by the test procedures discussed above,
the adhesive of this example will exhibit signi~icantly

7C)8~3
-40-
higher shear strength dnd approx~mately comparable or
higher peel, loop tack and corrugated hold values in
comparison to the adhesive of Example 15.
While part~cular embodiments of the inYention
have been descr~bed, it will be understood, of course~
that the invention is not limited to these embodiments,
since many obvious modifications can be made, and it
is intended to include within this invention any such
modifications as will fall within the scope of the
appended claims.

Representative Drawing