Release coating for adhesive articles and method

A polymer includes an ethylene-containing backbone having substituents attached thereto, wherein the substituents include a urethane linked nitrogen-bonded hydrocarbon side chain having about 5 carbon atoms or more in length and a terminal methyl group; and an oxygen linked water solubilizing group. The polymer is particularly useful in a release coating composition and is suitable for forming films from aqueous dispersions thereof, organic solvent dispersions thereof, or mixtures thereof.

BACKGROUND OF THE INVENTION 
Normally tacky and pressure sensitive adhesive (PSA) materials have been 
used for well over half a century. Products of this type, which take the 
form of tapes, labels, and other types of adhesive coated sheets, must be 
protected from unintended adhesion to other surfaces. Hence, tapes are 
typically wound into a roll on their own backing and labels are typically 
laminated to a release sheet to prevent their accidental adhesion to other 
surfaces and also to prevent their contamination with air-borne dust and 
other contaminants. In order to allow a roll of tape to be unwound without 
the undesirable transfer of adhesive to the tape baking, it is customary 
to provide the tape backing with a low adhesion backsize (LAB). Similarly, 
the release sheet or liner, to which the adhesive coated label is 
typically laminated, is supplied with a release coating to permit the easy 
removal of the liner from the label. This LAB or release coating is 
expected to reproducibly provide an appropriate level of release to the 
adhesive of interest, to not deleteriously affect the adhesive, and to be 
resistant to aging so that the release level remains relatively 
predictable with time. 
The Handbook of Pressure Sensitive Adhesive Technology, 2nd Ed., D. Satas 
Ed., Van Nostrand Reinhold, N.Y., 1989, Chapter 23, describes polymers 
which may be used as release agents for PSA tapes. Various polymers of 
lower critical surface tension such as silicones, fluorine-containing 
polymers, and long alkyl chain branched polymers are useful as release 
coatings. Long alkyl chain branched polymers are waxy compounds that can 
be used to prepare release coatings of medium release value which are 
especially desirable for PSA tapes. Many release coating patents describe 
the use of such long alkyl chain branched polymers. For example, 
Hendricks, U.S. Pat. No. 2,607,711 (1952) describes the use of copolymers 
of alkyl acrylate and acrylic acid for tape release coatings. According to 
Hendricks, all acrylates having an alkyl side chain of 16-20 carbon atoms 
are the more suitable, with octadecyl acrylate being the preferred 
comonomer. 
Examples of other long alkyl chain branched polymers or copolymers include 
stearyl methacrylate-acrylonitrile copolymer (U.S. Pat. No. 3,502,497); 
copolymers of stearyl acrylate or methacrylate with other monomers (U.S. 
Pat. No. 4,241,198); polyvinyl esters such as polyvinyl stearate, 
polyvinyl palmitate, polyvinyl arachidate, and polyvinyl behenate (U.S. 
Pat. No. 2,829,073); stearyl maleate-vinyl acetate copolymer (U.S. Pat. 
No. 3,285,771); polyvinyl stearate, polyvinyl laurate, copolymers of vinyl 
stearate with vinyl acetate and maleic anhydride, copolymers of octadecyl 
acrylate with other monomers (U.S. Pat. No. 2,913,355); polyethylene 
imines acylated with higher fatty acids (U.S. Pat. No. 3,510,342); 
poly-N-acyl imine (U.S. Pat. No. 3,475,196); solution polymers of vinyl 
stearate, allyl stearate, or vinyl octadecyl ether with maleic anhydride 
(U.S. Pat. No. 2,876,894); N-stearyl polyacrylamide (U.S. Pat. No. 
3,051,588); solution polymerized stearyl itaconate, monoacetyl itaconate, 
and monobehenyl itaconate (U.S. Pat. No. 3,052,566); copolymers of 
N-substituted long straight chain allyl maleamic acids and vinyl monomers 
(U.S. Pat. No. 3,342,625); and polyvinyl N-octadecyl carbamate prepared by 
reacting polyvinyl alcohol and octadecyl isocyanate (U.S. Pat. No. 
2,532,011). 
Other known release coating systems include an organic solvent based 
polymerization of a vinyl monomer of the general formula CH.sub.2 
.dbd.CR'COO(CH.sub.2 CHR"O).sub.n CONHR'" wherein R' and R" each represent 
a hydrogen or methyl group, R'" represents an alkyl group of at least 12 
carbon atoms or a fluoroalkyl group of at least 6 carbon atoms, and n is 
an integer of 1 to 6. Also known is the polymerization of the vinyl 
monomer with other vinyl compounds that does not include the preparation 
of water-borne LABs or release coatings from such monomers. Other known 
release coating systems include those that use surfactants (emulsifiers) 
in the stabilization of the polymer. For example, U.S. Pat. No. 5,516,865 
(Urquiola) describes a water-borne polymer composition having latex 
particles formed by emulsion polymerization including an emulsifier at a 
concentration of about 0.5 to about 8 weight percent based on the total 
weight of all monomers. The latex particles are formed by emulsion 
polymerizing long alkyl chain (meth)acrylate monomers and short alkyl 
chain (meth)acrylate monomers. U.S. Pat. No. 5,225,480 (Tseng et al.) 
describes a water-borne low adhesion backsize and release coating latex 
composition prepared by emulsion polymerization including about 0.05 to 
about 4 weight percent of an emulisifier. The latex particles are 
stabilized by the emulsifier within the aqueous phase.

SUMMARY OF THE INVENTION 
One aspect of the present invention is a release coating composition 
including a polymer containing a polyethylene backbone having substituents 
attached thereto. Preferably, the substituents include a urethane linked 
nitrogen-bonded hydrocarbon side chain having about 5 carbon atoms or more 
in length and a terminal methyl group; and an oxygen linked water 
solubilizing group. The substituents may further include hydrogen; a 
hydroxyl; a halide; an alkylene, an alkenylene, an alkynylene, an arylene 
group, or mixtures thereof, having a terminal hydroxyl group; 
##STR1## 
--O--R.sup.5 ; --R.sup.6 ; or mixtures thereof; wherein each R.sup.4, 
R.sup.5, and R.sup.6 is independently selected from the group of an 
aliphatic group, an aromatic group, and mixtures thereof. 
A water solubilizing group is a functionality capable of being ionized or 
is the ionized form thereof, which can either be anionic or cationic. For 
example, the water solubilizing group may include an acidic group capable 
of forming an anionic species. Preferably, when the water solubilizing 
group contains an anion, it is selected from the group of --OSO.sub.2 
O.sup.-, --SO.sub.2 O.sup.-, --CO.sub.2.sup.-, (--O).sub.2 P(O)O.sup.-, 
--OP(O)(O.sup.-).sub.2, --P(O)(O.sup.-).sub.2, --P(O.sup.-).sub.2, and 
--PO(O.sup.-).sub.2. Equally preferable is a water solubilizing group 
containing a cation selected from the group of --NH(R.sup.8).sub.2.sup.+ 
and --N(R.sup.8).sub.3.sup.+, wherein R.sup.8 is selected from the group 
of a phenyl group; a cycloaliphatic group; and a straight or branched 
aliphatic group having about 1 to about 12 carbon atoms. 
A release coating composition of the invention may be coated from an 
organic solvent, water, or mixtures thereof. Thus, the release coating 
composition may contain organic solvents, preferably selected from the 
group of an aromatic hydrocarbon, an ester, an aliphatic hydrocarbon, an 
alcohol, a ketone, and mixtures thereof; or it may contain water. 
As used herein, "release coating" refers to a component, preferably a film, 
that exhibits low adhesion to an adhesive, such as a pressure sensitive 
adhesive (PSA), so that separation occurs substantially between the 
adhesive and release coating interface. A release coating is also referred 
to as "low adhesion backsize" or LAB. Release coatings can be used in 
adhesive tape rolls, where the tape is wound upon itself and usage 
requires unwinding of the tape roll. Release coatings can also be used as 
a "liner" for other adhesive articles such as labels or medical dressing 
bandages, where the adhesive article is generally supplied as a sheet-like 
construction, as opposed to a roll construction. 
Optionally, a release coating composition of the present invention may 
further include an optional additive. Preferred optional additives are 
selected from the group of a crosslinker; a defoamer; a flow and leveling 
agent; a colorant; an adhesion promoter; a plasticizer; a thixotropic 
agent; a rheology modifier; a film former; a biocide/anti-fungal agent; a 
corrosion inhibitor; an antioxidant; a surfactant/emulsifier; an extender 
(e.g., polymeric emulsion, thickener, filler); and mixtures thereof. A 
preferred optional additive is an extender. 
In another aspect of the present invention, a release coating composition 
includes a polymer including a vinyl-derived backbone having substituents 
attached thereto. Preferably, the substituents include a urethane linked 
nitrogen-bonded hydrocarbon side chain having about 5 carbon atoms or more 
in length and a terminal allyl group; and an oxygen linked water 
solubilizing group, as defined above, wherein the release coating 
composition comprises about 0.5% by weight or less of a surfactant. 
Preferably, the vinyl-derived backbone is formed from one or more precursor 
compounds, which are selected from the group of ethylene, vinyl halides, 
vinyl ethers, vinyl esters, acrylic esters, methacrylic esters, 
(meth)acrylic acid, amides, aromatic vinyl compounds, heterocyclic vinyl 
monomers, allyl compounds, esters and half esters of diacids, and mixtures 
thereof. More preferably, the vinyl-derived backbone is a polymeric 
backbone component selected from the group of partially or fully 
hydrolyzed polyvinyl acetate, partially or fully hydrolyzed ethylene/vinyl 
acetate, and mixtures thereof. 
In yet another aspect of the invention, a composition for forming a release 
coating is provided, wherein the composition includes a polymer formed by 
combining a polymeric backbone component (e.g., hydrolyzed polyvinyl 
acetate) with an isocyanate-containing hydrocarbon having about 5 carbon 
atoms or more and a terminal methyl group and a water solubilizing 
compound. Optionally, a polymeric backbone component can be prepared by 
combining 1 or more precursors prior to combining with an 
isocyanate-containing hydrocarbon and/or a water solubilizing compound. 
In one preferred embodiment of the release coating composition of the 
present invention, a polymer includes units of the following formula: 
##STR2## 
wherein each R.sup.1 is independently selected from the group of hydrogen 
and an aliphatic group; and each R is independently selected from the 
group of X; a urethane-linked hydrocarbon of the formula: 
##STR3## 
wherein q is about 5 or more; and an oxygen linked water solubilizing 
group of the formula: 
##STR4## 
wherein each R.sup.3 is independently a divalent organic linking group and 
m is 0 or 1; and the X moiety is selected from the group of hydrogen; a 
hydroxyl group; a halide; an alkylene, an alkenylene, an arylene group, 
and mixtures thereof, having a terminal hydroxyl group; 
##STR5## 
--O--R.sup.5 ; or --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
is independently selected from the group of an aliphatic group, an 
aromatic group, or mixtures thereof; and further wherein each Y moiety 
independently comprises a functionality capable of being ionized or is the 
ionized form thereof; with the proviso that the polymer contains at least 
one each of the urethane linked hydrocarbon group and the oxygen linked 
water solubilizing group. 
In a further embodiment of the present invention, a release coating 
composition comprising a polymer comprising: 
##STR6## 
wherein each R.sup.1 is independently selected from the group of hydrogen 
and an aliphatic group; each X is independently selected from the group of 
hydrogen; a hydroxyl group; a halide; an alkylene, an alkenylene, an 
arylene group, or mixtures thereof, having a terminal hydroxyl group; 
##STR7## 
--O--R.sup.5 ; and --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
is independently selected from the group of an aliphatic group, an 
aromatic group, and mixtures thereof; and wherein each R.sup.3 is 
independently a divalent organic linking group and each Y is independently 
a functionality capable of being ionized or is the ionized form thereof, 
and further wherein q is about 5 or more; m is 0 or 1; x is about 0 to 
about 70; y is about 5 to about 95; and z is about 5 to about 50. 
Optionally, a release coating composition may further include an additive, 
as described above. 
Another aspect of the present invention provides a method for making a 
polymer. One preferred method includes the steps of admixing a polymeric 
backbone component and at least one organic solvent; adding an 
isocyanate-containing hydrocarbon having at least about 5 carbon atoms in 
length and a terminal methyl group to the admixture to modify the 
polymeric backbone component; and adding a water solubilizing compound to 
the admixture to modify the polymeric backbone component. 
Preferably, one or more precursors of the polymeric backbone component are 
selected from the group of ethylene, vinyl halides, vinyl ethers, vinyl 
esters, acrylic esters, methacrylic esters, (meth)acrylic acid, amides, 
aromatic vinyl compounds, heterocyclic vinyl monomers, allyl compounds, 
esters and half esters of diacids, and mixtures thereof. Preferably, the 
polymeric backbone component is selected from the group of partially or 
fully hydrolyzed polyvinyl acetate, partially or fully hydrolyzed 
ethylene/vinyl acetate, and mixtures thereof. 
A suitable water solubilizing compound is preferably capable of forming a 
water solubilizing group including an anionic group comprising an anion 
selected from the group of --OSO.sub.2 O.sup.-, --SO.sub.2 O.sup.-, 
--CO.sub.2.sup.-, (--O).sub.2 P(O)O.sup.- ; --OP(O)(O.sup.-).sub.2, 
--P(O)(O.sup.-).sub.2, --P(O.sup.-).sub.2, and --PO(O.sup.-).sub.2, once 
the water solubilizing compound modifies the polymeric backbone component. 
Similarly, another suitable water solubilizing compound is preferably 
capable of forming a water solubilizing group including a cationic group 
comprising a cation selected from the group of --NH(R.sup.8).sub.2.sup.+ 
and --N(R.sup.8).sub.3.sup.+, wherein R.sup.8 is selected from the group 
of a phenyl group; a cycloaliphatic group; and a straight or branched 
aliphatic group having about 1 to about 12 carbon atoms. Accordingly, a 
preferable water solubilizing compound is selected from the group of 
succinic anhydride, maleic anhydride, glutaric anhydride, phthalic 
anhydride, 2-sulfobenzoic acid cyclic anhydride, and mixtures thereof. 
In a method of making a polymer according to the present invention, a 
preferred organic solvent is selected from the group of an aromatic 
hydrocarbon, N-methyl-2-pyrrolidinone, dimethylformamide, diglyme, and 
mixtures thereof. Additionally, a method may further include a step of 
adding an optional additive selected from the group of a crosslinker; a 
defoamer; a flow and leveling agent; a colorant; an adhesion promoter; a 
plasticizer; a thixotropic agent; a rheology modifier; a film former; a 
biocide/anti-fungal agent; a corrosion inhibitor; an antioxidant; a 
surfactant/emulsifier; an extender; and mixtures thereof. Preferably, the 
method of the invention further includes a step of adding an optional 
additive comprising an extender to the release composition. 
In the method of the present invention, it may be desirable to add a salt 
forming compound, a solvent, and water; and remove the organic solvent to 
form an aqueous dispersion of the release coating composition. As used 
herein, an "aqueous dispersion" of a composition includes within its scope 
a composition that is dispersible, partially soluble, or readily soluble 
in water. Thus, a "dispersion" as used herein includes a "solution." 
Preferably, the salt forming compound may either be an organic base or an 
inorganic base. Preferable organic bases include tertiary amines. 
Preferable inorganic bases include hydroxides or carbonates of alkali 
metals. More preferable salt forming compounds are selected from the group 
of ammonia, ammonium hydroxide, trimethylamine, triethylamine, 
tripropylamine, triisopropylamine, tributylamine, triethanolamine, 
diethanolamine, dimethylethanolamine, and mixtures thereof. 
A further aspect of the present invention is an article including a backing 
having a first major surface and a second major surface; a pressure 
sensitive adhesive coated on the first major surface of the backing; and a 
low adhesion backsize coated on the second major surface. Preferably, a 
low adhesion backsize is formed from a release coating composition 
including a polymer containing an ethylene-containing backbone having 
substituents attached thereto. Preferably, the substituents include a 
urethane linked nitrogen-bonded hydrocarbon side chain having about 5 
carbon atoms or more in length and a terminal methyl group; and an oxygen 
linked water solubilizing group, as described above. 
Another aspect of the present invention provides a polymer containing a 
vinyl-derived backbone having substituents attached thereto. Preferably, 
the substituents include a urethane linked nitrogen-bonded hydrocarbon 
side chain having about 5 carbon atoms or more in length and a terminal 
alkyl group; and an oxygen linked water solubilizing group, as described 
above. 
Yet another aspect of the present invention is a polymer including repeat 
units of the following formula: 
##STR8## 
wherein each R.sup.1 is independently selected from the group of hydrogen 
and an aliphatic group; and each R is independently selected from the 
group of X; a urethane-linked hydrocarbon of the formula: 
##STR9## 
wherein q is about 5 or more; and an oxygen linked water solubilizing 
group of the formula: 
##STR10## 
wherein the X moiety is selected from the group of hydrogen; a hydroxyl 
group; a halide; an alkylene, an alkenylene, an arylene group, or mixtures 
thereof, having a terminal hydroxyl group; 
##STR11## 
--O--R.sup.5 ; and --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
is independently selected from the group of an aliphatic group, an 
aromatic group, and mixtures thereof, and further wherein each R.sup.3 is 
independently a divalent organic linking group, m is 0 or 1, and each Y 
moiety independently comprises a functionality capable of being ionized or 
is the ionized form thereof; with the proviso that the polymer contains at 
least one each of the urethane linked hydrocarbon group and the oxygen 
linked water solubilizing group. 
Still another aspect of the present invention provides a polymer including 
the following structure: 
##STR12## 
wherein each R.sup.1 is independently selected from the group of hydrogen 
and an aliphatic group; each X is independently selected from the group of 
a hydrogen; a hydroxyl group; a halide; an alkylene, an alkenylene, an 
arylene group, or mixtures thereof, having a terminal hydroxyl group; 
##STR13## 
--O--R.sup.5 ; and --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
is independently selected from the group of an aliphatic group, an 
aromatic group, and mixtures thereof; and wherein each R.sup.3 is 
independently a divalent organic linking group and each Y is independently 
a functionality capable of being ionized or is the ionized form thereof; 
and further wherein q is about 5 or more; m is 0 or 1; x is about 0 to 
about 70; y is about 5 to about 95; and z is about 5 to about 50. 
Another aspect of the present invention is an article including a porous 
backing having a first major surface and a second major surface; a 
pressure sensitive adhesive coated on the first major surface of the 
backing; and a low adhesion backsize coated on the second major surface. 
Preferably, the low adhesion backsize is formed from a release coating 
composition including a polymer containing an ethylene-containing backbone 
having substituents attached thereto. The substituents include, but are 
not limited to, a urethane linked nitrogen-bonded hydrocarbon side chain 
having about 5 carbon atoms or more in length and a terminal methyl group; 
and an oxygen linked water solubilizing group. Such an article may be a 
medical tape, or may include a hypoallergenic pressure sensitive adhesive. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
A composition in accordance with the invention includes a polymer having an 
ethylene-containing (e.g., vinyl-derived) backbone with substituents 
attached thereto. The polymer comprises repeat units of the following 
formula: 
##STR14## 
wherein in the polymer each R.sup.1 is independently selected from the 
group of hydrogen and an aliphatic group (preferably having 1 to 4 carbon 
atoms); and wherein each R is independently selected from the group of X, 
which can be hydrogen, a halide, or an organic group optionally containing 
heteroatoms or functional groups; a urethane linked nitrogen bonded 
hydrocarbon group, such as that shown by the following structure: 
##STR15## 
wherein q is about 5 or more; and an oxygen linked water solubilizing 
group, such as that shown by the following structure: 
##STR16## 
wherein each R.sup.3 is independently a divalent organic linking group 
(preferably having 1 to 20 carbon atoms), which includes aromatic groups 
and optionally heteroatoms or functional groups within the organic group, 
m is 0 or 1, and each Y is independently a functionality capable of being 
ionized or is the ionized form thereof, with the proviso that the polymer 
contains at least one each of the urethane linked nitrogen bonded 
hydrocarbon group and the oxygen bonded water solubilizing group. 
As used herein, the terms "organic group" and "organic linking group" means 
a hydrocarbon group that is classified as an aliphatic group, cyclic 
group, or combination of aliphatic and cyclic groups (e.g., alkaryl and 
aralkyl groups). In the context of the present invention, the term 
"aliphatic group" means a saturated or unsaturated linear or branched 
hydrocarbon group. This term is used to encompass alkyl, alkenyl, and 
alkynyl groups, for example. The term "alkyl group" means a saturated 
linear or branched hydrocarbon group including, for example, methyl, 
ethyl, isopropyl, t-butyl, heptyl, dodecyl, octadecyl, amyl, 2-ethylhexyl, 
and the like. The term "alkenyl group" means an unsaturated, linear or 
branched hydrocarbon group with one or more carbon-carbon double bonds, 
such as a vinyl group. The term "alkynyl group" means an unsaturated, 
linear or branched hydrocarbon group with one or more carbon-carbon triple 
bonds. The term "cyclic group" means a closed ring hydrocarbon group that 
is classified as an alicyclic group, aromatic group, or heterocyclic 
group. The term "alicyclic group" means a cyclic hydrocarbon group having 
properties resembling those of aliphatic groups. The term "aromatic group" 
or "aryl group" means a mono- or polynuclear aromatic hydrocarbon group. 
Such organic groups or organic linking groups, as used herein, include 
heteroatoms (e.g., O, N, or S atoms), as well as functional groups (e.g., 
carbonyl groups). 
Preferably, each X moiety is independently selected from the group of 
hydrogen; a hydroxyl group; a halide; an alkylene, an alkenylene, an 
alkynylene, an arylene group, or mixture thereof, having a terminal 
hydroxyl group (preferably having 1 to 10 carbon atoms); 
##STR17## 
--O--R.sup.5 ; and --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
is independently selected from the group of an aliphatic group, an 
aromatic group, and mixtures thereof, optionally containing heteroatoms or 
functional groups. Preferably, each R.sup.4, R.sup.5, and R.sup.6 
independently has 1 to 20 carbon atoms. 
Because each Y moiety is independently a functionality capable of being 
ionized or is the ionized form thereof, the polymer is capable of being 
dissolved or dispersed in water. Accordingly, a polymer of the present 
invention preferably contains the following units: 
##STR18## 
wherein each R.sup.1 is independently selected from the group of hydrogen 
and an aliphatic group (preferably having 1 to 4 carbon atoms), each X is 
independently selected from the group of hydrogen; a hydroxyl group; a 
halide; an alkylene, an alkenylene, an arylene group, or mixture thereof, 
having a terminal hydroxyl group; 
##STR19## 
--O--R.sup.5 ; and --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
is independently selected from the group of an aliphatic group, an 
aromatic group and mixtures thereof; and wherein each R.sup.3 is 
independently a divalent organic linking group; m is 0 or 1; q is about 5 
or more; and each Y is independently a functionality capable of being 
ionized or the ioinized form thereof. Thus, each Y is independently 
capable upon neutralization of dispersing (preferably, solubilizing) the 
polymer in water. The relative proportion of the units in a polymer 
according to the present invention is as follows: x is about 0 to about 
70; y is about 5 to about 95; and z is about 5 to about 50; wherein x, y 
and z each represent mole percent. 
As stated above, the water solubilizing group contains a functionality, 
labeled Y, that is capable of being ionized (such as an acidic group) or 
is the ionic form thereof that may be anionic or cationic. Examples of 
suitable anionic groups, which may be formed from acidic groups, include 
an anion selected from the group of --OSO.sub.2 O.sup.-, --SO.sub.2 
O.sup.-, --CO.sub.2.sup.-, (--O).sub.2 P(O)O.sup.- ; 
--OP(O)(O.sup.-).sub.2, --P(O)(O.sup.-).sub.2, --P(O.sup.-).sub.2, and 
--PO(O.sup.-).sub.2. Examples of suitable cationic groups include 
organo-ammonium groups that include a cation selected from the group of 
--NH(R.sup.8).sub.2.sup.+ and --N(R.sup.8).sub.3.sup.+, wherein R.sup.8 is 
selected from the group of a phenyl group; a cycloaliphatic group; and a 
straight or branched aliphatic group having about 1 to about 12 carbon 
atoms. Preferably, R.sup.8 is a lower alkyl group of about 1 to about 4 
carbon atoms. 
A polymer according to the invention may be used in compositions that are 
suitable as release coatings for use in adhesive articles, such a tapes, 
bandages, labels, to name a few. The release coating compositions of the 
present invention are capable of being dispersed and coated out of water, 
although they can also be dispersed and coated out of organic solvents or 
mixtures of organic solvents and water. As used herein, a "water 
dispersible" composition includes within its scope a composition that is 
only dispersible, partially soluble, or readily soluble in water. 
Polymeric Backbone Components 
A polymer according to the invention includes a backbone of repeating 
ethylene containing (e.g., vinyl-derived) units having substituents 
attached thereto, as shown above. A polymer according to the invention can 
be made by a variety of known methods. Preferably, it is made by modifying 
the polymeric backbone component by adding isocyanate-containing 
hydrocarbons and water solubilizing groups, both as shown above. For 
example, a polymeric backbone component preferably includes repeating 
ethylene containing units, such as a polyethylene, wherein the polymer has 
at least one pendant hydroxyl group attached thereto. This can be either 
purchased or prepared from smaller units (i.e., precursors). 
For example, the polymeric backbone can be formed from one or more 
precursors including, but not limited to, the group of ethylene, vinyl 
halides (e.g., vinylidene chloride), vinyl ethers (e.g., vinyl propyl 
ether), vinyl esters (e.g., vinyl acetate), acrylic esters (e.g., methyl 
acrylate), methacrylic esters (e.g., ethyl methacrylate), acids such as 
acrylic acid and methacrylic acid, amides (e.g., acrylamide), aromatic 
vinyl compounds (e.g., styrene), heterocyclic vinyl monomers, allyl 
compounds, esters and half esters of diacids (e.g., diethyl maleate), and 
mixtures thereof Of these, those that do not contain acrylate groups are 
the more preferred. 
Preferred polymeric backbone components are prepared from polymerizing and 
copolymerizing vinyl esters to afford, for example, polyvinyl acetate and 
ethylene/vinyl acetate copolymer, both fully or partially hydrolyzed, to 
form a polyvinyl alcohol. Some commercially available materials may retain 
acetate groups. These materials are also referred to herein as 
vinyl-derived and are preferably non-acrylate derived. 
Accordingly, a preferred backbone unit, prior to modification by an 
isocyanate containing hydrocarbon and a water solubilizing compound, in a 
polymer according to the invention has the formula: 
##STR20## 
wherein in the polymer each R.sup.1 is independently selected from the 
group of hydrogen and an aliphatic group. Each X moiety is preferably 
independently selected from the group of hydrogen; a hydroxyl group; a 
halide; an alkylene, an alkenylene, an alkynylene, an arylene group, or 
mixtures thereof, having a terminal hydroxyl group; 
##STR21## 
--O--R.sup.5 ; and --R.sup.6 ; wherein each R.sup.4, R.sup.5, and R.sup.6 
are independently selected from the group of an aliphatic group, an 
aromatic group, and mixtures thereof, with the proviso that at least one 
of the X substituents on the polymeric backbone is a hydroxyl group (prior 
to modification). It will be understood by one of skill in the art that 
because each R.sup.1 and X groups is independently selected from the above 
lists, the polymeric backbone component (prior to modification) may 
contain more than one type of unit. This is also true for the polymer 
according to the invention. One skilled in the art will further recognize 
that if X contains an alkylene, an alkenylene, an alkynylene group, an 
arylene group, or mixtures thereof having a terminal hydroxyl group, then 
that is the point of modification, and the resultant polymer will have a 
respective intervening group between the backbone and oxygen link. 
Isocyanate-containing Hydrocarbons 
As mentioned above, a composition according to the invention includes a 
polymer formed from modification of an ethylene-containing, preferably a 
vinyl-derived, backbone, as described above, with certain 
isocyanate-containing hydrocarbons. These hydrocarbons are also referred 
to herein as "hydrocarbon isocyanates." For example, reaction of a 
polyvinyl alcohol with an isocyanate results in the modification of 
hydroxyl groups on the backbone to urethane (or carbamate) groups. 
Preferably, the urethane links long side chain hydrocarbons which 
terminate with methyl groups. 
Preferably, these isocyanate-containing hydrocarbons are capable of forming 
urethane linked nitrogen-bonded hydrocarbon side chains having more than 
about 5 carbon atoms in length and a terminal methyl group. More 
preferably, the nitrogen bonded hydrocarbon side chains have at least 
about 12 carbon atoms, even more preferably at least about 14 and, most 
preferably, at least about 16 carbon atoms in length. The length of the 
hydrocarbon side chain affects the melting point of the polymer prepared 
therefrom, as taught by Dahlquist et al. (See e.g., U.S. Pat. No. 
2,532,011). If the length of the hydrocarbon side chain is too short, 
i.e., less than about 5, the long chain monomer does not crystallize at 
room temperature, and consequently, the side chain does not contribute to 
the release properties of the polymer prepared therefrom. 
Typically, hydrocarbon isocyanates have the general formula: 
EQU (C.sub.q H.sub.2q+1).N.dbd.C.dbd.O 
where q preferably has a value of more than about 5, more preferably, at 
least about 12, even more preferably at least about 14, and most 
preferably, at least about 16. One preferred hydrocarbon isocyanate for 
use in the present invention has the formula: 
EQU C.sub.18 H.sub.37.N.dbd.C.dbd.O 
(octadecyl isocyanate) which has 18 carbons in the nitrogen-linked alkyl 
chain. When, for example, this is reacted with polyvinyl acetate 
(partially or fully hydrolyzed), the resulting N-octadecyl carbamate side 
chains have the structure indicated by the formula: 
##STR22## 
where the carbon atom at the extreme right is one of those in the 
backbone, wherein each R.sup.1 is independently hydrogen or an aliphatic 
group. The nitrogen-linked group need not be a continuous aliphatic 
hydrocarbon chain, and may include other atoms or radicals capable of 
being present in the isocyanates, provided that they do not interfere with 
the desired release property of the polymer formed therefrom and that they 
permit a nitrogen-linked side chain which terminates with an alkyl group 
more than 5 carbon atoms in length having a terminal methyl group. 
Accordingly, one preferred unit in a polymer of the present invention 
having a urethane linked nitrogen-bonded hydrocarbon side chain having 
about 5 carbon atoms or more in length and a terminal methyl group 
attached thereto is: 
##STR23## 
wherein q is about 5 or more, each R.sup.1 is independently selected from 
the group of hydrogen and an aliphatic group and y is about 5 to about 95 
mole percent of the polymer. 
Water Solubilizing Compounds 
Water solubilizing groups preferably include functionalities capable of 
being ionized or are the ionic form thereof. These water solubilizing 
groups are hydrophilic so that when present in the polymer, they assist in 
solubility or dispersibility of the polymer in water and likely enhance 
the stability of aqueous water dispersions of the polymer. Typically, 
urethanes with long hydrocarbon side chains are hydrophobic and not 
readily water dispersible. Thus, a water solubilizing group may be 
incorporated in a polymer, in a nonionized form, that subsequently ionizes 
with the addition of a salt forming compound allowing the polymer to be 
dispersed in water. 
It is preferred to incorporate such water solubilizing groups into a 
polymer in accordance with the invention by means of a water solubilizing 
compound. "Water solubilizing compound" refers to a compound that has a 
water solubilizing group, as defined above, and is capable of being 
attached to the polymeric backbone via an oxygen linkage, preferably an 
ester linkage. Therefore, a water solubilizing compound may have the water 
solubilizing group in an ionized or a nonionized form. For example, a 
carboxylic acid group is an acidic water solubulizing group that can be 
ionized by salt formation, for instance, by reaction with a base. 
The water solubilizing groups preferably are derivatives of carboxylic 
acids and more preferably, derivatives of cyclic anhydrides. Most 
preferred water solubilizing groups may include aromatic moieties or alkyl 
chains that may be saturated or unsaturated, and linear or branched. 
Examples of preferred water solubilizing compounds that form water 
solubilizing groups, when attached to the polymer backbone, are succinic 
anhydride, maleic anhydride, glutaric anhydride, phthalic anhydride, and 
2-sulfobenzoic acid cyclic anhydride. Other water solubilizing compounds 
include those capable of reacting with the polymeric backbone component to 
form pendant water solubilizing groups such as halo-alkyl acids, e.g. 
chloroacetic acid. It is believed that the functionality on the polymer, 
preferably an ester linked acid group, is important for water 
dispersibility of the polymer because it can be neutralized by a base. 
As mentioned above, water dispersibility of the polymer is preferably 
accomplished by ionization of the water solubilizing group, preferably by 
the formation of a salt by the water solubilizing group. That is, the 
nonionized form of the water solubilizing group is soluble in an organic 
solvent (such as toluene) while the salt (or ionized) form of the water 
solubilizing group is dispersible in water. Thus, a salt forming compound 
is preferably selected from the group of organic bases and inorganic 
bases. One suitable class of an organic base includes a tertiary amine 
compound. Suitable inorganic bases include hydroxides or carbonates of 
alkali metals (e.g., potassium hydroxide). More preferably, a salt forming 
compound is selected from the group of ammonia, ammonium hydroxide, 
trimethylamine, triethylamine, dimethylethanolamine, tripropylamine, 
triisopropylamine, tributylamine, triethanolamine, diethanolalamine, and 
mixtures thereof. Triethylamine is a preferred salt forming compound. 
Accordingly, another preferred unit in a polymer of the present invention 
having a water solubilizing group attached thereto is: 
##STR24## 
wherein each R.sup.1 is independently selected from the group of hydrogen 
or an aliphatic group, each R.sup.3 is independently a divalent organic 
linking group, m is 0 or 1, each Y is independently a functionality 
capable of being ionized or the ionic form thereof, and z is about 5 to 
about 50 mole percent of the polymer. 
Consequently, a polymer so formed possesses a desirable structure 
exhibiting good film forming characteristics (i.e., polymeric particles 
have a propensity to coalesce and form a film) as well as good surface 
adhesion when coated on a substrate surface. Additionally, the polymer 
structure possesses good release properties (e.g., release values), which 
are stable upon aging against pressure sensitive adhesives (PSAs). It was 
found that lower amounts of water solubilizing groups in the polymer 
appear to yield better release, particularly under high humidity 
conditions (as indicated by the aging experiments herein). 
Optional Additives 
Other compounds, or additives, may be added to compositions including the 
polymer according to the invention to enhance or obtain particular 
properties. Such compositions are particularly useful as release coatings. 
Thus, suitable optional additives are those that preferably do not 
interfere with the film forming and release properties of a release 
coating composition according to the invention that may account for up to 
about 99% by weight of the release coating composition. Optional additives 
are preferably selected from the group of a crosslinker; a defoamer; a 
flow and leveling agent; a colorant (e.g., a dye or a pigment); an 
adhesion promoter for use with certain substrates; a plasticizer, a 
thixotropic agent; a rheology modifier; a film former (e.g., a coalescing 
organic solvent to assist in film formation); a biocide/anti-fungal agent; 
a corrosion inhibitor; an antioxidant; a photostabilizer (UV absorber); 
and a surfactant/emulsifier; and an extender (e.g., polymeric emulsion, 
thickener, filler); and mixtures thereof. 
Particularly useful optional additives from the group of extenders include 
thickeners (also referred to as wetting agents) that can be added to a 
release coating composition of the present invention as a cost savings 
measure and can be present in a release coating composition in an amount 
that does not significantly adversely affect release properties of a 
release coating so formed. Thickeners are usually cellulosic ethers that 
typically act by immobilization of water molecules and, consequently, can 
be added to increase the dispersion viscosity. Increase in dispersion 
viscosity is generally a function of thickener concentration, degree of 
polymerization, and chemical composition. An example of a suitable 
commercially available thickener is available under the trade designation 
NATROSOL from Aqualon Company, Wilmington, Del. A subset of thickeners 
include associative thickeners that can be added to increase viscosity. 
Associative thickeners typically have a hydrophilic and a hydrophobic 
portion in each molecule. It is believed that preferential interaction of 
these portions with themselves and with the polymer according to the 
invention form a three dimensional network structure within the 
dispersion. An example of a suitable commercially available associative 
thickener is available under the trade designation RHEOVIS CR2 from Allied 
Colloids, Suffolk Va. 
Other useful optional additives from the group of extenders can be in the 
form of polymeric emulsions. An example of suitable commercially available 
polymer emulsion includes a vinyl acetate/ethylene copolymer emulsion from 
Air Products, Inc., Allentown, Pa. 
Typically, conventional water-borne release coating compositions include a 
surfactant/emulsifier to stabilize the emulsion dispersion during 
polymerization and prior to coating. (See e.g., U.S. Pat. No. 5,225,480 to 
Tseng et al. and U.S. Pat. No. 5,516,865 to Urquiola). However, a release 
coating composition of the present invention is formed from a polymer that 
includes a water solubilizing group that is preferably a salt, as 
described above. In this instance, the release coating composition is 
preferably substantially surfactant-free. That is, a preferred release 
coating composition of the invention can include less than about 0.5 
weight percent, more preferably less than about 0.05 weight percent, of a 
surfactant for the purpose of stabilizing the emulsion dispersion during 
polymerization. Advantageously, it has been found that by modifying the 
polymer with an ionized form of a water solubilizing group, a surfactant 
is not required for either the formation of the polymer or to enhance the 
stability of the polymer for producing a water borne release coating. This 
is significant because in certain situations, it has been found that 
release coatings formed from release coating compositions including a 
surfactant may have a surfactant residue on an exposed surface of the 
release coating which may interfere with release properties of the release 
coating. 
The polymer of the present invention can be coated out of an organic 
solvent, water, or mixtures thereof (i.e., a carrier solvent). Preferably, 
it is coated out of water. Thus, compositions including a polymer in 
accordance with the invention may include an organic solvent when it is 
desired to coat the release coating composition from an organic solvent, 
such as aromatic hydrocarbons (e.g., toluene and xylene); esters (e.g., 
ethyl acetate); aliphatic hydrocarbons (e.g., heptane and hexane); 
alcohols (e.g., isopropanol and n-butanol); ketones (e.g., acetone and 
methyl ethyl ketone); and mixtures thereof. Other organic solvents that 
may be included are residual reaction solvents from the synthesis of the 
polymer, which include, preferably, N-methyl-2-pyrrolidinone, 
dimethylformamide, diglyme, and mixtures thereof. 
Method of Making Release Coating Compositions 
A release coating composition of the invention is preferably prepared by a 
method that includes admixing a polymeric backbone component with an 
isocyanate hydrocarbon and a water solubilizing compound, and inverting 
(or ionizing the nonionized form of a water solubilizing group) so that 
the release composition can be applied from an aqueous dispersion, 
although this need not be done if coating from an organic solvent. 
Typically, an admixture of a polymeric backbone component and at least one 
organic solvent are charged into a suitable reaction vessel. Preferred 
organic solvents include an aromatic hydrocarbon, 
N-methyl-2-pyrrolidinone, dimethylformamide, diglyme, and a mixture 
thereof. Examples of suitable aromatic hydrocarbon solvents include 
toluene and xylene. This admixture is dewatered via azeotropic 
distillation and then allowed to react with an isocyanate containing 
hydrocarbon, commonly at an elevated temperature of about 70.degree. C. to 
about 140.degree. C. until the isocyanate containing hydrocarbon is 
consumed, about 0.2 hour to about 12 hours. A water solubilizing compound, 
as defined above, is then added at an elevated temperature of about 
70.degree. C. to about 140.degree. C. until consumption of the water 
solubilizing compound (about 1 hour to about 12 hours). The resulting 
polymer may now be used in a release coating composition with optional 
additives, if it is desirable to coat the release coating composition out 
of an organic solvent. 
When the release coating composition is to be applied from an aqueous 
dispersion, it is converted to a water dispersible derivative thereof. 
Typically, this is accomplished by addition of a salt forming compound to 
the organic solvent dispersed polymer. A convenient method for providing 
an aqueous dispersion of a polymer according to the invention is to add 
the polymer to a mixture of an organic solvent (e.g., isopropanol), water, 
and a salt forming compound. The organic solvent can then be removed by 
distillation, for example, in a sufficient amount to form an aqueous 
dispersion of the polymer. While not wishing to be bound by any particular 
theory, it is believed that the salt forming compound neutralizes (or 
ionizes) the nonionized form of the water solubilizing group so as to 
"invert" the polymer to become water dispersible. It is further believed 
that the polymer remains as its inverted (or ionized) form dispersed in 
water, and then may revert to its original state (i.e., the water 
solubilizing group is in an acidic form) as the release coating 
composition dries on a substrate surface. Accordingly, there is no need to 
add surfactants/emulsifiers to achieve a stable aqueous dispersion of the 
polymer. 
Release coating compositions provided as aqueous dispersions of the 
polymer, besides being economical, eliminate many problems ordinarily 
associated with organic solutions and dispersions such as adverse effects 
of the organic solvent on the surface to be coated, fire hazards, health 
and toxicity dangers, odor, and other environmental and safety concerns 
during manufacturing. 
A release coating composition according to the invention may be clear, and 
is believed to be a solution, so that a substantially uniform film may be 
formed by coating at room temperature. However, a release coating 
composition according to the invention may be cloudy or opaque, wherein 
application of heat is required to coalesce particles of the release 
coating composition so that a substantially uniform film is formed. 
Release Coated Materials 
A composition of the present invention can be generally used as a release 
coating for a solid substrate, which may be a sheet, a fiber, or a shaped 
object. One preferred type of substrate is that which is used for pressure 
sensitive adhesive articles, such as tapes, labels, bandages, and the 
like. The composition may be applied to at least one major surface of 
suitable flexible or inflexible backing materials before drying is 
initiated. Useful flexible backing materials include paper, plastic films 
such as polypropylene, polyethylene, polyvinylchloride, 
polytetrafluoroethylene, polyester, polyethylene terephthalate, cellulose 
acetate, and the like. Backings can also be of woven fabric formed of 
threads of synthetic fibers or natural materials such as cotton or blends 
of these. Alternatively, backing materials may be nonwoven fabric such as 
air laid webs of synthetic or natural fibers or blends of these. In 
addition, suitable backings can be formed of metal, foils, or ceramic 
sheet material. Primers known in the art can be utilized to aid in the 
adhesion of the release coating composition to the substrate, although 
they are generally not necessary. 
The desired concentration of the polymer in a release coating composition 
depends upon the method of coating and upon the desired final coating 
thickness. Typically, a release coating composition is coated at about 1% 
to about 15% solids. 
A release coating composition may be applied to a suitable substrate by 
means of conventional coating techniques such as wire-wound rod, direct 
gravure, offset gravure, reverse roll, air-knife, and trailing blade 
coating. The coating can be dried at room temperature, at an elevated 
temperature, or a combination thereof, provided that the backing material 
can withstand the elevated temperature. Typically, the elevated 
temperature is about 60.degree. C. to about 130.degree. C. A resulting 
release coating provides an effective release for a wide variety of 
conventional pressure-sensitive adhesives such as natural rubber-based, 
acrylic, tackified block copolymer, and other synthetic film-forming 
elastomeric materials. 
A release coating of the present invention can be used in a variety of 
formats such as low adhesion backsize (LAB) for pressure-sensitive 
adhesive (PSA) tapes. For example, as shown in FIG. 1, a roll of tape 10 
includes a flexible backing 11, a pressure sensitive adhesive coating on 
one major surface 12 (i.e., a first major surface) of the backing and a 
release coating on the opposite major surface 14 (i.e., a second major 
surface) of the backing. The release coating is formed from the 
composition described above. The tape is wound into a roll such that the 
pressure sensitive adhesive releasably contacts the release coating. FIG. 
2 is an exploded cross-section of a segment of the tape 10 (FIG. 1). 
Referring now to FIG. 2, the tape 20 includes the backing 21, a pressure 
sensitive adhesive 22, and a release coating (or LAB) 23. The LAB 23 
results in a lower specific adhesion toward the pressure sensitive 
adhesive than does the surface of the backing on which the pressure 
sensitive adhesive is coated. This permits unwinding of the tape from a 
roll without offsetting or transfer of the pressure sensitive adhesive 
from the backing. Another format is a transfer tape including a film of a 
pressure sensitive adhesive between two release liners, at least one being 
coated with the release coating composition described above. 
Particularly preferred articles including a release coating (or LAB) of the 
invention are tapes, labels, wound dressings, and medical grade tapes. For 
example, one preferred wound dressing includes a polymeric film that is 
extremely thin, flexible, and supple such that it is conformable. The 
wound dressing is also typically supplied with a releasable protective 
liner covering the adhesive coated surface of the film. When the liner is 
removed and/or when the dressing is rubbed against clothing or bed linens, 
the LAB may prevent the adhesive coated film from wrinkling and adhering 
to itself and thus interfering with the smooth, aseptic application of the 
dressing to a patient's skin. Therefore, in addition to providing a low 
adhesion backsize coating on the surface of the film opposite the 
adhesive, it is also desirable to provide the surface with a low 
coefficient of friction to reduce edge lift of the dressing when rubbed 
against bed linen or clothing. 
A medical grade tape, or other article, may include a release coating 
composition of the invention. Medical grade tapes, or other articles, are 
typically "breathable," in that they are moisture vapor permeable due to 
the use of a porous backing. Such tapes may also include a variety of 
characteristics, such as softness and conformability. Woven, nonwoven or 
knitted materials are typically used as backings in such tapes. Examples 
of suitable backings include nonwoven fabrics such as carded, spun-bonded, 
spun-laced, air-laid, and stitch-bonded fabrics; woven fabrics having 
sufficient stretch to benefit from the use of an elastomer; and knitted 
fabrics such as warp-knitted and weft-knitted materials. 
Preferred backings exhibit a desired combination of properties such as 
moisture vapor transmission, softness, conformability, yield modulus, 
texture, appearance, processability, and strength. The particular 
combination of properties is typically determined by the desired 
application. For example, for many uses in the medical area, the fabric 
will have a low yield modulus and will be of sufficient strength for the 
desired application and for dispensation in a roll or pad form. 
Pressure sensitive adhesives can be any of a variety of materials known and 
are generally applied to a backing material. Generally, pressure sensitive 
adhesives are used in tapes wherein a tape includes a backing (or 
substrate) and a pressure sensitive adhesive. A pressure sensitive 
adhesive adheres with no more than applied finger pressure and can be 
permanently tacky. Pressure sensitive adhesives can be used with primers, 
tackifiers, plasticizers, and the like. The pressure sensitive adhesives 
are preferably sufficiently tacky in their normal dry state, and have a 
desired balance of adhesion, cohesion, stretchiness, elasticity and 
strength for their intended use. 
Tapes can be used in a wide variety of applications such as to adhere two 
surfaces together (e.g., flaps of packing material) or in the medical area 
(e.g., wound dressings). In the latter case, a pressure sensitive adhesive 
is a coating on the skin-facing side of the backing. Such adhesives are 
preferably "hypoallergenic" in that they exhibit acceptable performance in 
the 21-day Draize test on human subjects. 
EXAMPLES 
The objects, features and advantages of the present invention illustrated 
in the following examples, which incorporate particular materials and 
amounts, should not be construed to unduly limit this invention. All 
materials are commercially available from Aldrich Chemical, Milwaukee, 
Wis., unless otherwise stated or apparent. All parts, percentages, ratios, 
etc., in the examples are by weight unless otherwise indicated. 
NMR Test Method 
A sample of a polymer according to the invention (100 mg) was dissolved 
with heat in 1 g of deuterated chloroform. The sample was then loaded into 
a Varian INOVA 400 MHz Spectrometer (Varian NMR Instruments, Palo Alto, 
Calif.). 
Peel Strength Test Method 
This test measures the effectiveness of the release coating composition 
after a period of aging at room temperature or at an elevated temperature 
and at varying humidity conditions. The initial or aged release value is a 
quantitative measure of the force required to remove a flexible PSA tape 
from a substrate coated with the test composition at a specific angle and 
rate of removal. The force is expressed in Newtons (N) per 100 mm. 
Water dispersions of the release coating compositions were coated onto 
40-micron thick, flame-treated biaxially oriented polypropylene substrates 
using a #3 or #6 Mayer Bar. The coatings were dried in an oven and then 
allowed to cool in a constant temperature room. Dried release coatings had 
a thickness of approximately 0.1-0.2 microns. The dried coatings were 
conditioned (or aged) at room temperature and 50% relative humidity for 24 
hours. 
Aged release testing was conducted by rolling down 2.54 cm by 20 cm strips 
of a PSA tape onto the release coatings with 6 passes of a 2-kg rubber 
roller. The PSA tape/release coated film composites were allowed to age 
for the desired time/temperature conditions and were then adhered to a 
glass plate of a slip/peel tester (Model 3M90, IMASS Inc., Hingham, Mass.) 
with double coated tape. The force required to peel the test tape at a 
peel rate of 230 cm/minute at a 180.degree. peel angle from the release 
coating was then measured. 
Readhesion to Glass Test Method 
Readhesion to glass was measured by adhering the freshly peeled tape (from 
the above Peel Strength Test Method) to a clean glass plate and measuring 
the peel adhesion in normal fashion using the same slip/peel tester (Model 
3M90, IMASS Inc., Hingham, Mass.) from above, again peeling at 230 cm/min 
and at a 180.degree. peel angle. A 2-kg roller was used to roll down the 
tape onto the glass plate, and the readhesion was measured immediately 
without further dwell time. These measurements were taken to determine 
whether a drop in the adhesion value occurred due to undesirable 
contamination of the adhesive surface by the release coating. Readhesions 
are reported as the force (N/100 mm) required to remove the aged sample 
from a clean glass plate. The force to peel a control tape sample (which 
had not been adhered to the release coating) from a clean glass plate was 
also measured. 
"Unwind" and "Adhesion to Glass" Test Methods 
Unwind was measured by attaching a tape roll to a spool fixture of a 
slip/peel tester (Model 3M90, IMASS Inc., Hingham, Mass.) and the force 
required to unwind the tape from the tape roll was measured at a peel rate 
of 31 cm/minute at a 90.degree. angle with respect to the tape roll. The 
adhesion to glass was measured as described above in the Readhesion to 
Glass Test except that the tape sample was derived from a tape roll. 
Example 1 
This example describes the preparation, purification and recovery of a 
polymer having an acidic water solubilizing group according to this 
invention starting with a 98% hydrolyzed (by mole) polyvinyl acetate. 
The following ingredients were charged into a 250-ml round bottom flask: a 
polymeric backbone component of a medium MW polyvinyl alcohol prepared by 
hydrolyzing (98% by mole) polyvinyl acetate available under the trade 
designation ELVANOL 71-30 from Dupont, Wilmington, Del. (5 g, 113.5 
mmoles), N-methyl-2-pyrrolidinone solvent (80 ml), and toluene (20 ml). 
With heating and stirring, 19 ml of volatiles was distilled from the 
solution. The solution was placed in an oil bath at 125.degree. C. and an 
isocyanate-containing hydrocarbon, octadecyl isocyanate, available under 
the trade designation MONDUR O. Bayer Chemical Co., Leverkusen, Germany) 
(21.8 g, 73.8 mmoles) was then added over 5 minutes. After stirring for 15 
additional minutes, a water solubilizing compound, glutaric anhydride, 
(6.7 g, 58.8 mmoles) and diisopropylethylamine (7.55 g, 58.8 mmoles) were 
added sequentially and the solution was allowed to stir at 125.degree. C. 
for 5 hours. Work-up consisted of adding acetic acid (6 g, 100 mmoles), 
isopropyl alcohol (80 ml), and then methanol (100 ml) to precipitate out 
the product. Additional purification was accomplished by redissolving the 
product in isopropyl alcohol (80 ml) and then precipitating with the 
addition of methanol (40 ml). After drying, the product was isolated as a 
beige solid (28.7 g). 
Typical chemical shifts for Example 1 are shown by NMR analysis using 
methodology described above. .sup.1 H-NMR (CDCl.sub.3, 400 MHz) delta 
4.7-5.2 (at least two overlapping broad peaks, NH resonances of the 
urethane and R--OCH backbone resonances where R is not H), 3.8 (broad, OH 
of the alcohol), 3.7 (broad, HO--CH on backbone), 3.1 (broad, NHCH.sub.2 
methylene attached to urethane), 2.4 (broad, OOCCH.sub.2 CH.sub.2 CH.sub.2 
COOH methylenes attached to carbonyls on the water solubilizing group), 
1.1-2.0 (multiple peaks dealing with the methylene hydrogens), 0.88 
(triplet, CH.sub.3 terminal methyl group of urethane linked 
nitrogen-containing long chain alkyl substituent). Thus, integration of 
signals obtained by NMR analysis showed the Alkyl/Acid/OH molar ratio to 
be 70/22/8. 
Example 2 
This example describes the preparation, purification and recovery of a 
polymer having an acidic water solubilizing group according to this 
invention starting with a 98% hydrolyzed (by mole) polyvinyl acetate. 
The following ingredients were charged into a 1000-ml round bottom flask: a 
polymeric backbone component of a low MW polyvinyl alcohol prepared by 
hydrolyzing (98% by mole) polyvinyl acetate available under the trade 
designation AIRVOL 103 from Air Products, Allentown, Pa. (30 g), 
N-methyl-2-pyrrolidinone solvent (420 ml), and toluene (330 ml). With 
heating and stirring, 227 ml of volatiles was distilled from the solution. 
The solution was placed in an oil bath at 100.degree. C. and an 
isocyanate-containing hydrocarbon, octadecyl isocyanate (145.1 g) was then 
added over 3 minutes. After stirring for 15 additional minutes, a water 
solubilizing compound, glutaric anhydride, (17.99 g) and 
diisopropylethylamine (22.2 g) were added sequentially and the solution 
was allowed to stir at 90.degree. C. for 5 hours. Work-up consisted of 
filtering the hot solution over diatomaceous earth and then precipitating 
with the addition of methanol (900 ml). After drying, the product was 
isolated as a white solid (150 g). 
Typical chemical shifts for Example 2 were exemplified as recited for 
Example 1, except that the mole percent ratio of the alkyl, acid and 
alcohol portions of the polymer in Example 2 were derived from integration 
of the signals located at 0.88, 2.4, and 3.7 ppm, respectively, in the 
spectrum. Thus, integration of signals obtained by NMR showed the 
Alkyl/Acid/OH molar ratio to be 67/11/22. 
Example 3 
This example describes the preparation, purification and recovery of a 
polymer having an acidic water solubilizing group according to this 
invention starting with a 50% hydrolyzed (by mole) polyvinyl acetate. 
The following ingredients were charged into a 250-ml round bottom flask: a 
polymeric backbone component of a polyvinyl alcohol prepared by 
hydrolyzing (50% by mole) polyvinyl acetate available under the trade 
designation POLYVIOL W45-450 from Wacker Chemie GmbH, Munich, Germany (2.5 
g, 18.73 mmoles) and xylenes solvent (60 ml). With heating and stirring, 
10 ml of volatiles was distilled from the solution. An 
isocyanate-containing hydrocarbon, octadecyl isocyanate, (3.92 g, 13.3 
mmoles) was added and the solution was heated to reflux for 3 hours. A 
water solubilizing compound, succinic anhydride, (0.543 g, 5.42 mmoles) 
and triethylamine (0.60 g, 5.9 mmoles) were added sequentially and the 
solution was heated to reflux for 4 hours. Work-up consisted of adding 
isopropyl alcohol (50 ml) and then precipitating by pouring into a 
solution of methanol (100 ml) and acetic acid (10 g). Additional 
purification was accomplished by redissolving the product in isopropyl 
alcohol (10 ml) and then precipitating with the addition of methanol (20 
ml). After drying, the product was isolated as a fluffy white solid. 
Typical chemical shifts for Example 3 were exemplified as recited for 
Example 1, except that the mole percent ratio of the alkyl, acid and 
alcohol portions of the polymer in Example 3 were derived from integration 
of the signals located at 0.88, 2.4, and 3.7 ppm, respectively, in the 
spectrum. Thus, integration of signals obtained by NMR showed the 
Acetate/Alkyl/Acid/OH molar ratio to be 52/35/10/3. 
Example 4 
This example describes the preparation, purification and recovery of a 
polymer having an acidic water solubilizing group according to this 
invention starting with a fully hydrolyzed ethylene/vinyl acetate 
copolymer. 
The following ingredients were charged into a 250-ml round bottom flask: a 
polymeric backbone component of an about 40,000 MW "ethylene vinyl 
alcohol" copolymer prepared by fully hydrolyzing an ethylene (44% by 
mole)/vinyl acetate copolymer available under the trade designation EVAL E 
105A (EVALCA Co., Lisle, Ill.) (1 g, 15.13 mmoles), diglyme solvent (15 
ml), and xylenes (7.5 ml). With heating and stirring, 8.5 ml of volatiles 
was distilled from the solution. An isocyanate containing hydrocarbon, 
octadecyl isocyanate, (2.91 g, 9.85 mmoles) was added and the solution was 
heated to reflux for 3.5 hours. A water solubilizing compound, succinic 
anhydride, (0.58 g, 5.8 mmoles) and diisopropylethylamine (0.75 g, 5.8 
mmoles) were added sequentially and the solution was heated to reflux for 
5 hours. Work-up consisted of adding isopropyl alcohol (7 ml) and then 
precipitating by pouring into a solution of methanol (15 ml) and acetic 
acid (1.5 g). After drying, the product was isolated as a fluffy white 
solid. 
Typical chemical shifts for Example 4 were exemplified as recited for 
Example 1, except that the mole percent ratio of the alkyl, acid and 
alcohol portions of the polymer in Example 4 were derived from integration 
of the signals located at 0.88, 2.4, and 3.7 ppm, respectively, in the 
spectrum. Thus, integration of signals obtained by NMR showed the 
Alkyl/Acid/OH molar ratio to be 64/30/6. 
Example 5 
This example describes the preparation of a polymer according to this 
invention dispersed in water formed from the polymer of Example 1, wherein 
the water solubilizing group is neutralized to form a water dispersible 
polymer. 
The polymer product of Example 1 (25 g) was dissolved in isopropanol (50 g) 
and a salt forming compound, triethylamine, (6 g) by heating at reflux for 
about 5 minutes. With vigorous stirring, a 1:1 water/isopropanol mix (20 
g) was slowly added to the still hot solution and then water (500 g) was 
added over 3 minutes. Using a rotoevaporater, 95 g of liquid was removed 
and then the solution was filtered over diatomaceous earth. The resulting 
solution was a slightly yellow, transparent, 5% dispersion of the 
polymeric composition in water. 
Example 6 
This example describes the preparation of a polymer having a neutralized 
water solubilizing group according to this invention dispersed in water by 
starting with a 98% hydrolyzed (by mole) polyvinyl acetate. 
A polymeric backbone component of a low molecular weight polyvinyl alcohol 
prepared by hydrolyzing (98% by mole) polyvinyl acetate available under 
the trade designation AIRVOL 103 (100 g) and N-methyl-2-pyrrolidinone 
solvent (333 g) were added to a vessel equipped with a mechanical stirrer 
(glass rod, teflon blade) and a Dean/Stark trap with a nitrogen inlet. The 
mixture was heated in an oil bath at 125.degree. C. for 30 minutes with 
stirring to dissolve the polyvinyl alcohol. Heptane (enough to fill the 
Dean/Stark trap plus 50 ml) was added and the mixture heated at reflux to 
dewater the solution (30 minutes). The heptane was then distilled off to 
redissolve the polymer (about 30 minutes). An isocyanate-containing 
hydrocarbon, octadecyl isocyanate, (484 g) was added over about 5 minutes 
to the solution with stirring. After about 30 minutes, a water 
solubilizing compound, solid glutaric anhydride, (34.9 g) was added all at 
once with stirring. After about 4.5 hours, the solution was cooled to 
100.degree. C. and methanol (1500 ml) was added with stirring. The mixture 
was heated at reflux and stirred for 5 minutes and the liquid portion then 
decanted off while still hot. This step was repeated using 1400 ml of 
methanol, and the methanol then removed by distillation at 125.degree. C. 
Isopropyl alcohol (2500 g) and a salt forming compound, triethylamine, 
(34.1 g) were added and the resulting mixture heated at reflux until the 
solid product was dissolved. With rapid stirring, hot deionized water 
(80.degree. C., 5570 ml) was added over 1 minute and the solution heated 
at reflux to distill off 3531 g of liquid. The pH of the resulting 
solution was adjusted to 8 with triethylamine and the solution filtered 
over diatomaceous earth. The resulting 12% dispersion of polymeric 
composition in water was slightly yellow/transparent to beige/cloudy in 
appearance. 
Typical chemical shifts for Example 6 were exemplified as recited for 
Example 1, except that the mole percent ratio of the alkyl, acid and 
alcohol portions of the polymer in Example 6 were derived from integration 
of the signals located at 0.88, 2.4, and 3.7 ppm, respectively, in the 
spectrum. Thus, integration of signals obtained by NMR showed the 
Alkyl/Acid/OH molar ratio to be 71/12/17. 
Example 7 
This example describes the preparation of a polymer having a neutralized 
water solubilizing group according to this invention dispersed in water 
starting with a 98% hydrolyzed (by mole) polyvinyl acetate. 
A polymeric backbone component of a low molecular weight polyvinyl alcohol 
prepared by hydrolyzing (98% by mole) polyvinyl acetate available under 
the trade designation AIRVOL 103 (8.7 parts) and N-methyl-2-pyrrolidinone 
solvent (29.1 parts) were added to a vessel equipped with a mechanical 
stirrer and a decanter trap. The mixture was heated at 125.degree. C. for 
30 minutes with stirring to dissolve the polyvinyl alcohol. Heptane 
(enough to fill the Dean/Stark trap plus 50 ml) was added and the mixture 
heated at reflux to dewater the solution (30 minutes). The heptane was 
then distilled off to redissolve the polymer (about 30 minutes). An 
isocyanate-containing hydrocarbon, octadecyl isocyanate, (42.2 parts) was 
added over about 3 minutes to the solution with stirring. After about 30 
minutes, a water solubilizing compound, solid glutaric anhydride, (3 
parts) was added all at once with stirring. After about 4.5 hours, the 
solution was cooled to 100.degree. C. and propylene glycol (65 parts) and 
deionized water (120 parts) were added with stirring. The mixture was 
heated at reflux and stirred for 10 minutes and the liquid portion then 
decanted off while still hot (about 50.degree. C.). This step was repeated 
using 300 parts of deionized water. Isopropyl alcohol (150 parts) and a 
salt forming compound, triethylamine (3 parts), and water (150 parts) were 
added and the solution was heated at reflux to distill off 135 parts of 
liquid. The pH of the resulting dispersion was adjusted to 8 with 
triethylamine and the milky dispersion (24.7% solids) was drained from the 
vessel. A portion (97.2 parts) of this dispersion was added back into the 
vessel along with deionized water (173.4 parts), isopropanol (113.4 
parts), and triethylamine (0.09 parts). The solution was heated at reflux 
for 30 minutes to distill off 150 parts of liquid and then filtered 
through two 20-micron filters to yield an 11% solids milky white 
dispersion that was then diluted with the addition of deionized water to 
give a 10% solids dispersion. 
Typical chemical shifts for Example 2 were exemplified as recited for 
Example 1, except that the mole percent ratio of the alkyl, acid and 
alcohol portions of the polymer in Example 2 were derived from integration 
of the signals located at 0.88, 2.4, and 3.7 ppm, respectively, in the 
spectrum. Thus, integration of signals obtained by NMR showed the 
Alkyl/Acid/OH molar ratio to be 75/11/14. 
Examples 8-22 
Additional polymeric compositions of this invention were prepared according 
to the above examples with minor variations in reactant amounts and 
reaction conditions. Polymeric compositions in Examples 8-12 were prepared 
as in Example 1. Polymeric compositions in Examples 13-14 were prepared as 
in Example 2. Polymeric compositions in Examples 15-22 were prepared as in 
Example 3. The NMR-determined molar ratios of the resulting polymers are 
provided in Table 1. 
TABLE 1 
______________________________________ 
"Polyvinyl Alcohol" 
Molar Ratio 
Ex. Starting Material Acetate Alkyl Acid OH 
______________________________________ 
8 ELVANOL 71-30 1 64 35 0 
9 ("98% Hydrolyzed" Polyvinyl 
1 69 10 20 
Acetate) 
10 ELVANOL 50-42 (Dupont) 
12 68 14 06 
("88% Hydrolyzed, High MW" 
Polyvinyl Acetate) 
11 ELVANOL 51-05 (Dupont) 
12 65 15 08 
12 ("88% Hydrolyzed, Low 
12 62 20 06 
MW" Polyvinyl Acetate) 
13 POLYVIOL W45-450 51 36 4 9 
14 ("50% Hydrolyzed" Polyvinyl 
51 28 6 15 
Acetate) 
15 EVAL E 105A 0 45 42 13 
16 ("Fully Hydrolyzed" "44% 
0 76 10 14 
17 Ethylene"/Vinyl Acetate 
0 59 39 2 
18 Copolymer) 0 81 4 15 
19 0 57 26 17 
20 0 42 6 52 
21 0 36 4 60 
22 EVAL L 101(EVALCA) 
0 80 13 7 
("Fully Hydrolyzed" "27% 
Ethylene"/Vinyl Acetate 
Copolymer) 
______________________________________ 
Example 23 
The feasibility of coating polypropylene film with a water-dispersible 
release coating composition containing a water dispersible polymer having 
a neutralized water solubilizing group and an associative thickener 
additive was demonstrated in this example. 
An associative thickener, a 30% aqueous dispersion available under the 
trade designation RHEOVIS CR2 (Allied Colloids, Suffolk Va.) (0.068 g), 
was added to 10 g of a 10% water dispersion of the water dispersible 
polymer prepared in Example 7. The mixture was stirred for about 5 seconds 
and the resulting solution hand coated onto a 15 cm.times.60 cm sheet of 
50-micron, flame-treated, biaxially oriented polypropylene (BOPP) film 
with a #6 Mayer Bar (RDS Specialties, Webster, N.Y.) which spread the 
solution evenly over the film. The film was dried at 110.degree. C. for 
about 1 minute in a drying oven to afford a clear-coated film. 
Example 24 
The feasibility of coating polypropylene film with a water-dispersible 
release coating composition containing a polymer having a neutralized 
water solubilizing group and a viscosity modifier additive was 
demonstrated in this example. 
A 0.5% aqueous dispersion of a viscosity modifier available under the trade 
designation NATROSOL (Aqualon Company, Wilmington, Del.) (9.38 g) was 
added to 10 g of a 10% water dispersion of the polymer prepared in Example 
7. The mixture was stirred for about 5 seconds and the resulting solution 
hand coated onto a 15 cm.times.60 cm sheet of 50-micron, flame-treated, 
BOPP film with a #6 Mayer Bar which spread the solution evenly over the 
film. The film was dried at 110.degree. C. for about 1 minute in a drying 
oven to afford a clear-coated film. 
Example 25 
The feasibility of coating cellulose acetate film with a water-dispersible 
release coating composition containing a polymer having a neutralized 
water solubilizing group and no additives was demonstrated in this 
example. 
A 12% water dispersion (about 0.25 ml) of the polymeric composition 
prepared in Example 6 was hand coated onto a 15 cm.times.60 cm sheet of 
matte-finished cellulose acetate film with a #6 Mayer Bar which spread the 
solution evenly over the film. The film was dried at ambient conditions 
for about 15 minutes to afford a clear-coated film. 
Examples 26-28 
These examples describe the testing of various PSA tapes applied to a 
polypropylene substrate coated with a blend of a water-dispersible release 
coating composition of a polymer having a neutralized water solubilizing 
group and a waterborne film former that alone does not provide a release 
surface. 
A 55% aqueous emulsion of a film former (a vinyl acetate/ethylene copolymer 
emulsion available under the trade designation AIRFLEX 100HS from Air 
Products, Inc., Allentown, Pa.) (8.2 g) was added to 5 g of a 10% water 
dispersion of the polymer prepared in Example 7. Water (86.8 g) was added 
to provide a solution containing 5% solids which was then hand coated 
using a #6 Mayer Bar onto BOPP and tested for peel strength and readhesion 
to glass using 3 commercial pressure sensitive adhesive (PSA) tapes 
according to the Peel Strength and Readhesion Test Methods described 
above. The different commercially available tapes (all from 3M Company, 
St. Paul, Minn.) were evaluated and the test results are provided in Table 
2. 
TABLE 2 
______________________________________ 
Readhesion to 
Peel Strength (N/100 mm) 
Glass 
1 Week at 
1 Week at 
(N/100 mm) 
(21.degree. C./ 
(50.degree. C./ 
(1 wk 
Exp. Tape Sample Initial 
50% RH) 
50% RH) 
at 50.degree. C.) 
______________________________________ 
26 SCOTCH Brand 
2.88 5.17 4.67 37 
MAGIC Tape (Control = 27) 
(3M Company, 
St. Paul, MN) 
27 SCOTCH Brand 
5.50 5.81 5.50 30 
CRYSTAL (Control = 28) 
CLEAR Tape 
(3M Company, 
St. Paul, MN) 
28 SCOTCH Brand 
5.33 7.80 5.20 23 
SATIN Tape (Control = 22) 
(3M Company, 
St. Paul, MN) 
______________________________________ 
Desired target peel strength for the tapes in Table 2 range from 4 to 8 
N/100 mm. The data in Table 2 show that the tapes in Examples 26-28 
display release and readhesion from this range of acrylate adhesive tapes. 
Example 29 
This example describes the preparation and testing of a backing material 
suitable for use as a wound dressing tape coated with a water-dispersible 
release coating composition of a polymer of Example 2 having an acidic 
water solubilizing group. An aqueous dispersion of the polymer from 
Example 2 was prepared using the method of Example 5 except that the 
amount of water was adjusted to result in an 8% solids dispersion. 
An 8% solids aqueous dispersion of the polymeric composition described in 
Example 2 was coated onto a porous, nonwoven fibrous tape material 
prepared in accordance with the description found in U.S. Pat. No. 
3,121,021 (Copeland) that did not yet have a release coating. The coating 
was accomplished via a nipped gravure station using a 90 line ruling mill 
gravure roll and the residence time in a 130.degree. C. drying oven was 10 
seconds. The resulting tape roll was then aged at various conditions and 
tested for unwind and adhesion to glass according to the methods described 
above. Test results are compared with results from commercially available 
MICROPORE Tape (3M Company, St. Paul, Minn.) in Table 3. 
TABLE 3 
______________________________________ 
Unwind Adhesion to Glass 
(N/100 mm) (N/100 mm) 
11 Days at 
14 Days at 
After 11- 
After 14- 
50.degree. C./ 
50.degree. C./ 
Day Day 
Tape Sample "Dry" 90% RH Aging Aging 
______________________________________ 
Nonwoven/porous 
3.3 14.2 23.0 18.6 
Tape 
MICROPORE 5.5 12.0 23.0 19.7 
Brand Tape 
(Commercial Product) 
______________________________________ 
The desired peel strength of MICROPORE brand tape ranges from 3 to 18 N/100 
mm. The data in Table 3 show that the test tape displays desirable release 
and readhesion characteristics. Noteworthy is the fact that the peel 
strength does not increase prohibitively with aging. The readhesion does 
decrease somewhat but is comparable to the commercially available product. 
Examples 30-32 
These examples describe the testing of rubber-based, Kraton-based, and 
acrylic-based PSA tapes applied to a polypropylene substrate coated with 
various water-dispersible release coating compositions. 
Aqueous dispersions of the polymers from Examples 1 and 4 were prepared 
using the method of Example 5 except that the amount of water added was 
adjusted to result in 10% solids dispersons. These water-borne release 
coating compositions were hand coated onto aminated butadiene primed 
polyester film using a #3 Mayer Bar and tested for Peel Strength and 
Readhesion to glass using 3 commercial PSA tapes according to the Test 
Methods described above. The different commercially available tapes (all 
from 3M Company, St. Paul, Minn.) evaluated and the test results are 
provided in Table 4. 
TABLE 4 
______________________________________ 
Peel Strength 
(N/100 mm) Readhesion to 
3 Days at 
3 Days at 
Glass (N/100 mm) 
23.degree. C./ 
50.degree. C./ 
(After 3-Day Aged 
Exp. Tape Sample 50% RH 50% RH Peel) 
______________________________________ 
30 3M Brand #232 
21.3 16.6 43.8 
Masking Tape (Control = 43.0) 
(Rubber-Based 
Adhesive) 
(Polymer from 
Example 1) 
31 SCOTCH Brand 5.3 6.8 34.0 
MAGIC Tape (Control = 27.0) 
(Acrylic-Based 
Adhesive) 
(Polymer from 
Example 1) 
32 3M Brand #375 
1.9 2.8 92.0 
Box Sealing Tape (Control = 88.0) 
(Kraton-Based 
Adhesive) 
(Polymer from 
Example 4) 
______________________________________ 
The data in Table 4 show that the tapes of Examples 30-32 displayed 
desirable release and readhesion from the different classes of pressure 
sensitive adhesives. 
The complete disclosures of all patents, patent applications, and 
publications are incorporated herein by reference as if individually 
incorporated. Various modifications and alterations of this invention will 
become apparent to those skilled in the art without departing from the 
scope and spirit of this invention, and it should be understood that this 
invention is not to be unduly limited to the illustrative embodiments set 
forth herein.