Note: Descriptions are shown in the official language in which they were submitted.
l ~
~ 5'~g4~
TERPOLYMl~RS OF STYR~:NE, ISOBUTYLENE A~1D BETA-PINENE
Specifi~cation
This invention relates to new terpolymers, to prepara-
tional methods therefor and to novel resinous compositions
containing such terpolymers. More particularly, this invention :~
relates to homogeneous random low molecular weight terpolymers
of styrene, isobutylene and beta-pinene.
The polymerization of styrene with other monomers
to form both copolymers and terpolymers is well known. The
preparational methods used during polymerization are deter-
minative of the class of polymer ob;ained. Thus, typically
in cationic polymerizations, low polymerization temperatures
are employed to prepare high molecular weight polymers whereas
high preparational temperatures are used to obtain low molecu-
lar weight polymers. The low molecular weight polymers, i.e.
those having a number average molecular weight below 20,000
are often used in hot melt coating as well as hot melt adhe-
sive applications. Ih such app~ications the polymers are
typically combined with microcrystalline or paraffin waxes.
However~ it has been found that polymers containing large -
proportions of styrene exhibit inco~patibility with hydrocarbon
waxes.
It has now been found that certain terpolymers of
styrene, isobutylene and beta-pinene possess highly desirable
properties including improved compatibility with both paraffin
and microcrystalline waxes and are therefore particularly
useful in hot melt coatings and adhesives. Further, these
polymers are useful for preparing novel pressure-sensitive
adhesives. More specifically, the present invention resides
in a solid, homogeneous and essentially random terpolymer
of styrene, isobutylene and beta-pinene having a number average
molecular weight of from about 1500 to about`7000, a styrene
.
~5;~946
content of from about 40 to about 60 weight percent, an iso-
butylene content of from about 10 to about 40 weight percent,
a beta-pinene content of from about 10 to 40 weight percent
and a ring and ball softening point of from about 160F to
about 240F. :
The terpolymers of this invention, as indicated,
are characterized by a high degree of randomness, that is, ~ .
the terpolymers consist essentially of basic repeating units
of the fo1lowing formule:
'' ' '.~ '`
":
. ~'` ~ .
'
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. .
:
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~5~946
. ~' ' I -
/=\
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~ - u - m
. ~ $
cm _ C ~ ~3 c~ - m -
C~
m
a~
.` ' ~ ' ~ '
~`` C~ -~ ~ - c~ ' .
:~ C,~
; I
~} C,~
: ~
:~ , C) -: '
,~, ~ ..
C~_ _
m - c~ - ~7 ;.
r r
~ Cl~
`~ C~- .
~ . . .
m - c~
m - c~--m
. . I~ I . ,,. ,1 ,
., .. ~. .
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~5~946
wherein a, b, c, d, e, f and g are integers from 0 to 10
provided that at least one of a, d and g, at least one of
b and f and at least one of c and e is greater than zero;
and provided that 104(a+b+g) ~ 136~b+f2 ~ 56(c+e~ does not
exceed the numerical value of about 7000; and n is a number
ranging from about _ 1500__ to
104(a+d+g) + 136(-b+f) +-S-6 rc+e)
about 7000 . It can be seen that
104(a+d+g~ ~+ 136(b+f) + 56~c+e-~
in the foregoing quotients the values 104, 136 and 56 repre-
sent the molecular weight of the styrene, beta-pinene and ~ -
isobutylene radicals respectively. Thus the terpolymers of -
this invention do not contain long sequences of styrene, iso-
butylene or beta-pinene units. This distinguishes the polymers
of the present invention from block-type polymers which essen-
tially contain long sequences of the individual monomer units ~ -
along the molecular chain. It also distinguishes the polymers -`
from graft-type polymers where repeating units of one monomer
are attached to a backbone chain of another. Furthermore -
the polymers of the present invention do not contain long
se~uences of alternating monomer units.
- 20 In addition to indicating the random nature of thepolymers of this invention the above formula also illustrates
the specific nature of the terpolyrners in that there are sub-
stantially no ring alkylated styrene or beta-pinene residues
in the polymer arising from an in situ alkylation of the
styrene or beta-pinene by the isobutylene. As further illus-
trated by the structural formula above, the polymerization of
the isobutylene unit takes place in such a manner that there
.,, :
; are two methyl groups and not only one perpendicular to the
molecular chain.
, 30 The molecular weight of the terpolymers of this
invention in contradistinction to other typical polymers
--4--
: . .
. . .
105'~946
containing styrene is rather low and moreover must be within
a limited range in order that the terpolymers possess the
desired set of properties. Generally the polymers of this
invention have a number average molecular weight ranging from
about 1500 to about 7000. In a preferred embodiment of this
invention, however, the terpolymers have a molecular weight
ranging from about 2000 to a~out 4500. As used herein molecu-
lar weight is described both in terms of the weight average
molecular weight '~1w' and the number average molecular weight
Mn. However, unless specified to the contrary, when used
herein and in the appended claims molecular weight will mean
the number average molecular weight Mn. The significance
of these conventional molecular weight terms as well as methods
for their determination are more fully described in Structure
of Polymers, M. I. Miller, Reinhold, New York, 1966.
The terpolymers of styrene, isobutylene and beta-
pinene of this invention are solid materials having relatively
high heat softening points. As measured by the ring and ball
method, the heat softening point of the terpolymers ranges
from about 160F to about 240F. A more limited range of
from about 175F to about 230F is preferred, however, for
maximizing the usefulness of the terpolymers in such applica- ~
tions as components of resinous compositions used for hot ~-
melt coatings or adhesives. A further characterizing property
of the terpolymers of this invention is that they have good
thermal stability and are stable against decomposition to
~ temperatures of about 480F. Accordingly these polymers can -~
4' be suitably employed in applications without decomposition
where high temperatures are likely to exist or occur. This
3~ is particularly important in such polymer uses as hot melt
coatings and hot melt adhesives which are subjected to elevated
temperatures during their application. The particular soften-
. , .
~5~ 946
ing point of the terpolymers is partially dependent on the
individual monomer concentration of such polymer. The soften-
ing point is particularly a function of the isobutylene content -
of each terpolymer. Higher softening points are obtained
from polymers with lower isobutylene contents and lower soften-
ing points are obtained with higher isobutylene contents.
~ While the terpolymers of this invention are defined
by reference to their composition and to the above characteriz- i
.
ing properties such as molecular weight, softening point and -
randomness, such properties are interrelated to the specific
method of preparation. Accordingly in preparing the terpolymers
: .
` of this invention a specific preparational method should be
utilized in order that all of the above described properties .~-
.:. -
be obtained. Utilization of such methods not only permits
the obtainment of the desired ~erpolymers but in addition ;~
achieves such result with almost theoretical conversions and ` -
in a particular convenient and desirable industrial manner.
This preparational method involves an interrelated combination
of processing features which basically comprise an elevated
polymerization temperature, a particular catalyst system and - -
a certain mode of conducting the polymerization reaction.
; This method is effected, in general, by gradually bringing
the styrene, isobutylene and beta-pinene into reactive contact,
in the presence of a hydrocarbon polymerization solvent, with
a catalyst system of a primary catalyst and a cocatalyst while
maintaining a particular polymerization temperature.
The catalyst system which is utilized in preparing
the terpolymers of this invention is composed of a primary
catalyst and a cocatalyst which are maintained in a specific
relative proportion. Both the selection of the primary catalyst
and the cocatalyst and their relative proportions in the cata-
lyst system ~re important to the s~ccess of produ~ng high
~,o5~ 946
yields of terpolymers having all of the ultimately desired
properties. The primary catalyst can consist of at least one
alkyl aluminum dihalide wherein the alkyl group contains from
1 to about 5 carbon atoms, including such groups as methyl,
ethyl, propyl, butyl, isobutyl and isopentyl. The halide por-
tion can be a halogen atom such as chlorine and ~romine. Thus,
exemplary primary catalysts are methyl aluminum dichloride,
ethyl aluminum dichloride, propyl aluminum dichloride, n-butyl
; aluminum dichloride, isobutyl aluminum dichloride, pentyl
10 aluminum dichloride, methyl aluminum dibromide, ethyl aluminum
dibromide, propyl aluminum dibromide and the like. The pre-
ferred primary catalyst for preparing the terpolymers of the
present invention is ethyl aluminum dichloride.
; The cocatalyst utilized in combination with the
primary catalyst in the catalyst system comprises at least
one material selected from the group consisting of water, ~ -
an alkyl halide, a hydrogen halide or an alcohol. Examples -
of these cocatalysts include alcohols such as alkanols having
from 1 to about 5 carbon atoms in the alkyl portion of the -
molecule such as ethyl alcohol, propyl alcohol, t-butyl alcohol
or mixtures thereof; secondary or tertiary alkyl halides where
the alkyl portion contains from 3 to 5 carbon atoms such as
propyl chloride, butyl chloride and pentyl chloride; or a
, hydrogèn halide such as hydrogen chloride or hydrogen bromide.
Of the various catalysts which can be employed an alkanol
such as tertiary butyl alcohol or an alkyl halide such as ~`
` tertiary butyl chloride and especially water are preferred
particularly when used in combination with the preferred pri-
mary catalyst, ethyl aluminum dichloride. Thus, the most
preferred catalyst system is ethyl aluminum dichloride in
combination with water.
*~l
--7--
' . . , - ; '
o5~ 946
The relative proportion or ratio of the cocatalyst
to catalyst in the catalyst system is important in preparing
the terpolymers of the present invention having the desired
set of properties. ~hile the ratio can vary depending upon -;
such factors as the particular catalyst and cocatalyst used
it should be maintained within certain limits to obtain the
desired terpolymers. Generally, the cocatalyst should be
present in the catalys~ system within a range of from about ~; `2 to 30 mole percent based upon the mole percent of the primary
catalyst present. A more limited range of from about 3 to
15 or about 5 to 10 is preferred for such cocatalysts as water
particularly when used with the preferred primary catalyst
ethyl aluminum dichloride.
The quantity of the primary catalyst used in the
catalyst system which in turn determines the quantity of co- -
catalyst can also be varied. The particular amount used is -~
dependent upon such factors as the particular primary catalyst,
the cocatalyst and the polymerization temperature. General~y
the quantity of the primary catalyst can range from about
0.20 to about 1.5 weight percent based upon the combined weight
of the styrene, isobutylene and beta-pinene monomers. A more
limited range of about 0.3 to about 1.0 is preferred, however,
when e~ploying catalyst systems containing ethyl aluminum
dichloride in combination with cocatalysts such as water, ~ .
alkyl halides or alkanols.
In preparing the catalyst system the cocatalyst
and the primary catalyst can be admixed in the desired ratio ;
prior to the polymerization. More preferably it can be pre-
pared in the presence of the solvent just prior to polymeriza-
tion by simply adding the appropriate quantities of catalyst
and cocatalyst to the solvent with mixing. The primary cata- i`
lyst itself can also be prepared in situ during or just prior
~ -8-
....
, ; : .
~o5~ 946
to the polymerization ~y com~ining the necessary materials
to form the desired alkyl aluminum dihalide. For example
aluminum chloride can be admixed with diethyl aluminum chloride
in the appropriate proportion to form the active preferred
ethyl aluminum dichloride catalyst in situ. It is preferred,
however, to add the primary catalyst as a relatively pure
compound to the solvent used as the polymerization medium
together with the cocatalyst just prior to polymerization.
~he temperature utilized in effecting the polymeri- `
zation is, as previously indicated, higher than normally uti-
lized for the cationic copolymerization of styrene with other
monomers. Utilization of such high temperatures in combination
with the catalyst system as well as with the mode of conducting
the polymerization permits the attainment of the unique ter-
polymers of this invention. Moreover, employment of this
elevated temperature allows the polymerization to be conducted -
~in a highly convenient and industrially desirable manner.
The polymerization temperature can range from about 10C to
about 50C with the specific temperature utilized within this
range being dependent upon such factors as the catalyst system
employed, the solvent and the ultimately desired properties
of the terpolymers. Usually a more limited temperature range
of from about 25C to about 45C and particularly from about
- 30C to about 35C is preferred.
The hydrocarbon solvent used to effect the polymeri- --
zation can include a wide class of hydrocarbon polymerization
solvents. The particular solvent employed in the polymeriza- -
` tion will affect the ultimate properties of the terpolymer
produced. Accordingly, it is important to select a solvent
or combination of solvents which provides a terpolymer having
the desired properties. The solvents which can be used indi-
vidually or in combination include aliphatics such as alkanes
105,~46
having from S to about 10 carbon atoms such as he~ane or
heptane and aromatics such as benzene or alkylated benzenes
such as toluene, xylene or ethylbenzene. Of the various sol-
vents which can be used the preferred solvents are hexane,
heptane or mixtures thereof, with the most preferred solvent
being hexane. The quantity of solvent employed can be varied
- but there should at least be a quantity of solvent present
sufficient to provide a readily stirrable reaction mixture.
Typically when using solvents such as hexane a desirable amount
ranges from about 0.5 to about 2.0 weight parts or preferably
equal weight parts of solvent per one weight part of the com-
bined styrene, isobutylene and beta-pinene charge.
In carrying out the preparation of the terpolymers
of the present invention another processing feature is the
, particular mode used to bring the monomer charge into reactive
contact with the catalyst system. It is important that the
styrene, isobutylene and beta-pinene mixture be gradually con-
tacted with the catalyst system in the presence of the solvent
if the desired properties in the polymers are to be achieved.
This contacting is preferably effected ~y gradually adding
the monomer mixture to the solvent containing the catalyst
system while maintaining the desired polymerization tempera-
` ture. In gradually adding the styrene, isobutylene and beta-
pinene, preferably admixed in a single feed stream, the time
required to complete the addition will vary depending upon
such factors as the particular catalyst system, the polymeri-
zation temperature utilized and to a lesser extent the scale
of the reaction. Generally, however, the styrene, isobutylene
and beta-pinene should be added at a rate adjusted so that
~ 30 they are substantially completely polymerized upon contact
with the catalyst system leaving no unreacted monomer in the
reaction mixture. Typically, this addition time can range
~ .
-lQ-
?
105'~'~t46
from about 0.1 to about 2 hours with add~tion times of from
about 0.5 to about l.S hours being preferred. The charge
stream of monomers can contain from about 40 to about 60 weight
percent styrene, from about 10 to about 40 weight percent
isobutylene and from about 10 to about 40 weight percent beta-
pinene depending upon the compositional makeup desired in the
final polymer. ;
` The polymerization method for preparing the polymers
of this invention can be conducted in a batch, semi-batch
or continuous operation. A batch operation is usually suitable,
however, and one exemplary procedure involves gradually adding
a single stream of styrene, isobutylene and beta-pinene mono-
mers, admixed in the desired weight ratio, to the stirred
solvent containing the appropriate catalyst system. The gradual
addition of the monomers is adjusted so that substantially
all of the styrene, isobutylene and beta-pinene are polymerized
upon contact with the catalyst system leaving substantially
no unreacted monomer in the reaction mixture. During the
, addition, the temperature of the exothermic reaction is main-
tained within the desired range by utilizing appropriate cooling
means. When the addition of the monomers is complete, the
terpolymer produced can then, if desired, be recovered from
the reaction mixture. It is generally desirable, however,
to leave the polymer in the reaction mixture in the presence
of the catalyst system at the polymerization temperature for
a residence period sufficient to insure total, uniform polymeri-
zation. The length of this residence time can range from -
only a few minutes to one hour or more. Typically residence
- periods ranging from 0.25 to about 2 hours are used. After
3Q the terpolymer has been in contact with the catalyst system
for a sufficient residence period it can be removed from the
reaction mixture and purified according to several different
--11--
.. . .
,
1~5'~946
procedures. Advantageously, the removal procedure involves
first eliminating the catalyst system from the reaction mixture.
This can be carried out by first deactivating the catalyst
with the addition of methanol to the reaction mixture followed
by a neutralization of the catalyst with base such as calcium
hydroxide. The reaction mixture can then be filtered to remove -
the catalyst and neutralizing base. After the catalyst system
has been eliminated, the solvent and any impurities formed
in the polymerization can be readily removed from the reaction
mixture by distillation at reduced pressure leaving the desired -
~terpolymer in high yield.
The terpolymers of this invention and the manner
in which they can be prepared is more specifically illustrated
in the following example wherein the preparation of a series
of terpolymers is detailed.
Example 1
A series of terpolymers in accordance with the present
invention were prepared by the following procedure:
, ~ ,
A monomer charge was prepared by first charging
styrene, dried in a molecular sieve column, and beta-pinene, ~ ;
dried by distillation under reduced pressure, into a steel
~ ~,
cylinder which was dried by vacuum pumping. The cylinder
was cooled in a dry ice bath and isobutylene monomer was added
as a liquid in slight excess to the steel cylinder. The monomer
charge was adjusted to the proper weight ratio by venting
off the excess isobutylene and the cylinder was pressurized
with nitrogen gas to a pressure of about 200 p.s.i.g. Oven
baked polymerization equipment consisting of a 1 liter 3-necked
flask equipped with a gas inlet tube, a mechanical stirrer,
a thermometer and a dry ice condenser was cooled to room tem-
perature under a flow of dry nitrogen gas. Hexane, dried
by passage through a molecular sieve column, was then charged
~oszs46
into the flask. The hexane solvent wa~ degassed by slowly
bubbling nitrogen gas through the gas inlet tu~e for a period
of about 30 minutes. Water cocatalyst was added to the flask
and the mixture was stirred for a period of about 15 minutes.
Ethyl aluminum dichloride catalyst (25 weight percent in hexane)
was then added and the resulting mixture was ased for a period
- of about 15 minutes. A small amount of the monomer charge
was introduced into the flask and the mixture was aged for
a period of about 15 minutes. After this time the remaining
monomer charge was added to the flask through the gas inlet
tube with vigorous stirring over a period ranging from about
15 to about 45 minutes. The reaction temperature during this
time was maintained within the desired range by intermittent
cooling with a dry ice acetone bath. After the addition was
completed stirring was continued to ensure completion of the
reaction. The catalyst system was then deactivated ~y the
addition of methanol (10 ml) and neutralized through the addi~
tion of calcium hydroxide (13 grams). The reaction mixture -
was then suction filtered through a sintered glass funnel
containing a bed of diatomaceous earth. The filter bed was '
washed with toluene to ensure complete transfer of polymer.
The filtrate was then concentrated by distillation at ambient -~ -
pressure to a temperature of 200C and was then stripped of ; -
remaining volatile components at a temperature of 225C and
at a pressure of 0.35 mm of mercury to yield the desired ter~
`i polymer.
The polymerization conditions employed in the prepara-
tion of a series of terpolymers of this invention are isummarized
in Table I and the properties of these polymers are summarized
in Table II.
In Table II the molecular weights reported were
determined using Vapor Pressure Osmometry techniques. The
-13-
.~ ,
~05Z946
heat softening point was obtained by the Ring and Ball method
of AS~M ~ 28-67. The iodine number was determined using ASTM
method D 1959~6.1.
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105'~946
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-16-
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~05'~946
TABLE II
POLYMRP~ PROPERTI~S
Number Gardner
Average Viscosity Gardner Color
Polymer Molecular Softening 70% Solids 50% Solids Iodine
No. Wt. Point ~ in Toluene in Toluene Number
1 2419 209 Zl to Z2 cl 75
2 2689 208 ~Z6 <1 74
3 2639 210 >Z6 ~1 71
104 2717 213 U to V cl 79
2350 210 Y to Z cl 81 .
~ '
6 2532 219 I to J <1 77
7 2600 208 V to W <1 80 ~
8 2403 209 Z4 ~1 79 ~ ,
9 2878 211 Z6 ~1 74
-; : .
3169 215 Y ~1 79
11 2331 207 Z to Zl <1 80
, 12 3158 220 Z <1 78
~:~ 13 2519 205 V to W ~1 80
2014 3290 221 Z to Zl <1 80
3073 216 M <1 81
16 -- 218 Z3 <1 80
17 3120 219 S cl --
18 4820 218 -- ~1 83
19 2331 213 M ~1 78
20 . 4500 228 V <1 81
21 2444 189 ~A ~1 56
` 22 3480 201 Q ~1 59
23 4510 203 V <1 61
3Q 27 2940 209 -- - <1 78
28 2662 185 -- <1 55
29 2570 230 Y to Z cl 113
' '
`,,- . . ' "
-17-
. . . .
-
~05'~946
To demonstrate the random nature of the terpolymers
of the present invention as well as their homogeneity, samples
of polymers Nos. 20 and 22 were fractionated as follows:
To a five percent solution of the polymer in benzene,
methanol was added dropwise until an opalescent solution was
- obtained. The precipitated polymer was allowed to settle
and the supernatant liquid was decanted. The precipitated
polymer was washed with methanol and dried. The methanol
, solution was added dropwise to the decanted supernatant solution
to obtain another opalescent solution. Repeated precipitation
and isolation of resin samples from solvent mixtures containing
increased methanol concentrations were carried out to give
the results set forth in Table III for the two polymers of
this invention. ~his data demonstrates both the random nature
as well as the compositional homogeneity of the terpolymers ~ -
of this invention.
TA~LE III
`~ ANALYSIS OF TERPOLYl~ERS AND THEIR FRACTIONS
Num~er
Fraction Average
of Sample % % Iso- % Molecular
Wt. % Styrene butylene ~-Pinene Weight
Polymer No. 20 100.052.7 12.8 34.5 4,500
Fraction 119.9 51.7 6.3 42.018,560
Fraction 226.9 53.4 8.6 38.0 4,475 -~
Fraction 318.9 54.212.3 33.5 4,080
-~ Fraction 434.3 50.619.9 29.5 2,770
Polymer No. 22 100.053.5 22.0 24.5 3,480
Fraction 120.4 53.719.3 27.0 3,350
Fraction 227.2 53.322.7 24.0 3,140
Fraction 321.0 54.522.5 23.0 3,200
Fraction 431.4 49.027.5 23.5 2,290
-18-
~OS,~ 9 ~
The terpolymers o~ th~ prD s~nt invention must be
prepared from the beta isomer of pinene to the substantial
exclusion of alpha-pinene. Whereas the utilization of the
beta isomer of pinene produces polymer in high yield, i.e.
greater than 90 percent, provided the reaction conditions
set forth above are utilized, the utilization of alpha-pinene
or even mixtures of alpha- and ~eta-pinene result in catalyst
poisoning and low yields. To demonstrate the criticalness
of utilizing beta-pinene in the terpolymers of this invention
experiments were carried out wherein varying amounts of beta-
pinene were substituted with alpha-pinene in the preparation
of terpolymers. In each instance low yields of polymer were
obtained. The preparational conditions and yields of polymer
obtained in these experiments is set forth in Table IV. ~-
TABLE IV
POLYMER NO.
31 32 33
Styrene/Iso-
butylene/~-
Pinene/~-Pinene
Monomer Wt.
Ratio 50/20~27/350/20/24/650/20/15~1550/20/0/30
Primary Catalyst
Wt. % Based on
Combined Monomer
~ei~ht Ratio 0.5 0.5 0.5 0-5 --
Cocatalyst ~H2O)
Mole % Based on
Primary Catalyst 5 5 5 5
3Q Polymerizatign
Temperature C20-25 20-25 20-25 20-25
- Addition Time
! (.~inutes) 15 15 15 15
:.
Residence Time
(Minutes) 45 45 45 45
Yield Percent87.4 86.6 75.2 58.9
~os;~s46
As previously indicated the terpolymers of styrene,
isobutylene and beta-pinene are useful for a variety of dif-
ferent polymeric applications. One especially useful applica-
tion is utilization of the copolymers as components of resinous
compositions used for hot melt resins. These hot melt resinous
compositions are typically composed of an admixture of a
primary resin component, a wax component, and a modifying
resin component which serves to compatibilize and otherwise
improve the properties of the primary resin and wax component.
These hot melt resin compositions are used primarily in coating
and adhesive applications. For example, in coating applications
they are used to coat substrates such as cloth, paper or card-
board to provide a moisture and vapor impermeable coating
or surface. In adhesive applications these resin compositions
are used to bond layers of paper or cardboard to form laminates
of such materials which possess great strength as well as
being impervious to water or moisture vapors. A particular
requirement of these hot melt resinous compositions is that
they have a desirable combination of melting points and viscosi- -
ties or molten viscosity which permits them to be machineapplied at high speed to the particular substrates. Aside
from such basic properties, however, these resins must, as
films or coatings, also have a combination of other suitable
properties such as low water vapor transmissivity, strength,
elasticity, glossiness, thermal stabili~y, good adhesiveness
;~ and hot tack, as well as a good color.
A hot melt resinous composition having a particularly
~: desirable set of these properties is obtained according to
this invention by utilizing the instant terpolymers as the
modifying resin component of such resinous compositions in
combination with the primary resin and the wax component.
The primary resin component which can be combined with the
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wax component and the terpolymers of this invention to form
the hot melt resinous compositions can include a wide variety
of materials. Generally most of the materials commonly
employed as the primary resin component of hot melt resinous
compositions can be suitably utilized. Typically, these
materials include polyethylenes, polypropylenes, ethylene-vinyl
acetate copolymers or various combinations thereof. Usually
ethylene-vinyl acetate copolymers are preferred as the primary
resin component. Suitable copolymers of ethylene and vinyl
acetate which can be employed have a melt index in the range
of 2.5 to 550 using the ASTM Procedure D-1238. These copolymers
advantageously contain a vinyl acetate monomer content in the
range of from about 5 to 45 weight percent and more typically
` from about 15 to about 42 weight percent.
The wax component which can be compounded with the
primary resin component and with the terpolymer of this inven-
tion can be selected from a wlde group of waxes and wax com-
binations. Suitable waxes include aliphatic hydrocarbon waxes, ?
for example, paraffin waxes of various melting points ranging
from about 120F to about 165F; microcrystalline and crystal-
line waxes having melting points of from about 140F to about
200F; natural vegetable waxes, such as carnauba or beeswax;
or synthetic waxes such as hydrogenated castor oils or poly-
ethylene oxides. Of the various waxes which can be utilized
as the wax component, however, paraffins and microcrystalline
waxes are generally preferred. This is especially the case
when employed in combination with ethylene-vinyl acetate co-
polymers as the primary resin, since the paraffins yield better
moisture proofing and are generally lighter in color. Fre-
guently, it is desirable to employ the paraffin waxes in com-
bination with the microcrystalline waxes especially when in-
creased adhesiveness is desired. These preferred paraffins
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have a melting point of from about 145F to about 165F.
The particular formulation of the hot melt resinous
composition of this invention in respect to the proportions
of the primary resin component, the wax component and the
styrene, isobutylene and beta-pinene terpolymer can be widely
varied. The particular proportions for any formulation are ;
selected depending upon such factors as the intended applica- -
tion. Usually, for most hot melt resin applications, the
i terpolymer of this invention can constitute from about lO
; 10 to about 60 weight percent of the resinous composition. A
more limited range of from about 20 to about 40 weight percent
is preferred especially when the primary resin is a copolymer
of ethylene-vinyl acetate as heretofore described and the ~ ~`
wax is a paraffin or microcrystalline wax. The amount of ~ ;
^ wax component and primary resin component can also be varied.-
Generally the quantity of primary resin can range from about ;
10 to about 65 weight percent of the total composition with
a range of from about 20 to about 40 weight percent being -~
preferred. The quantity of wax component can range from about
20 to about 80 weight percent with a range of from about 25 -~
to about 65 weight percent being preferred.
Thus a further embodiment of the present invention
resides in a hot melt resinous composition comprising from
;l about lO to about 65 weight percent of a primary resin, from
about 20 to about 80 weight percent of a wax and from about
lO to about 60 weight percent of the terpolymer of this inven-
tion.
The hot melt resinous compositions can be prepared
or formulated by employing conventional resin blending pro-
cedures. The procedures typically involve mixing, blending,
or milling the components, if necessary under application
of heat, in the desired respective proportions to obtain a
., .
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substantially homogeneous, one phase, or completely di~persed
mixture. The hot melt resinous compositions thus prepared
can be applied according to standard coating and adhesive
techniques to such substrates as cloth, paper or cardboard
to form moisture impermeable coatings or laminates of such
materials having high strength and water vapor imperviousness;
The hot melt resinous compositions of this invention
are more specifically illustrated in the following example.
Example 2
The polymers of Example 1 were utilized to prepare
hot melt resinous compositions by blending the respec,tive
terpolymer with a primary resin and a wax. The primary resin
component consisted essentially of an ethylene-vinyl acetate
copolymer (Elvax 350, Du Pont) having a vinyl acetate monomer
content of about 25 weight percent and a melt index of 17.3
to 20.9 (AST~ D-1238). The wax component consisted essentially
of a microcrystalline wax (~obilwax 2305) having a melting
point of about 176F. One percent by weight of antioxidant -,
was added and the components were blended to form a hot melt ~
. . .
resinous composition. The terpolyme~s of Example 1, the ,'~primary resin and the wax component were present in equal
parts in all of the compositions.
The cloud point of each of the hot melt resin compo-
, sitions of Example 2 was determined by heating a sample of
each of the compositions in a 16 mm test tube in a forced
~' ~ air oven to a temperature of about 400F. The samples were
then permitted to cool with stirring and the temperature at ~--
-` which the melted composition became hazy was recorded as its -~
cloud poin~. The results of the procedure are shown in Table V.
'~
~ . .
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105'~94~;
TABLE V
Composition of Resin Formulation, Cloud
.Poly~er No. Weight Percent Point
Primary
Terpolymer Wax Resin
1 33 33 33 196
2 33 33 33 197
3 33 ~ 33 33 196
4 33 33 33 196
7 33 33 33 199
8 33 33 33 198
. ~ 33 33 33 197
33 33 33 228
11 33 33 33 203
12 33 33 33 279
13 33 33 33 195
` 14 33 33 33 289
` 15 33 33 33 240
:. .
.. 16 33 33 33 207
20 17 33 33 33 234 .
:.` 18 33 33 33 232 .
. 21 33 - 33 33 199
~;-` 24 33 . 33 i3 196 ,-
.' 25 33 33 33 196 -
26 33 33 33 196
28 10 75* 15** . 156
28 33 50* 17** 153
*par.affin wax having a melt point of 150F ~ASTM D-87) -
**ethylene vinyl acetate copolymer having a vinyl acetate
30monomer content of 28% and a melt index of 22 to 28
, :
,,.
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.
105'~46
The terpolymers of this invention can also be used
to prepare novel pressure-sensitive adhesive compositions,
particularly solution type pressure-sensitive adhesive compo-
sitions.
Pressure-sensitive adhesives may be defined as an
adhesive material which adheres tenaciously upon application
of only light finger pressure and can be removed cleanly from
the surface to which it is applied. These pressure-sensitive
adhesives are useful for a variety of different purposes. Most
commonly, however, they are used to form pressure-sensitive ~;
adhesive tapes by application of the adhesive composition to
a substrate tape comprising such materials as cloth, paper or
a polymeric film. Typically, these pressure-sensitive adhesives -~
are composed of an elastomer component and a tackifier compo-
:.,. ~.,
nent. In order that these adhesive materials be suitable as
,
pressure-sensitive adhesives, they must possess the minimum
requirements of wetting ability or "quick stick," good cohesive- ;
ness and good adhesiveness in the proper respective balance. ;~
A pressure-sensitive adhesive composition having the
; 20 proper balance of these properties is obtained by utilizing
the terpolymer of this invention as the tackifying component
in combination with an elastomer component.
The elastomer component which can be combined with
- the terpolymer of this invention can include a wide variety -
of different materials. Generally, most of the materials ;
`'r' commonly employed as the elastomer component of pressure-
sensitive adhesives can be suitably utilized. Typically, ~ -
these elastomer materials include rubbery materials such as ~-~
reclaimed rubbers, natural rubber, styrene butadiene rubber,
,. ..
polyisoprene, polyisobutylene or butyl rubber, or butadiene
acrylonitrile rubber, block copolymer of styrene and butadiene
; or styrene and isoprene, or.polyvinyl ethers and polyacrylate
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' ''~ ' ' ' '. . ' '-,'
105;~946
esters, or various com~inations thereof. Of thR various
elastomeric materials which can be employed, the rubber
elastomers such as natural rubber are preferred.
~ he formulation of the pressure sensitive adhesive
compositions of this invention in respect to the proportions
of the terpolymer tackifier and the elastomer can be varied.
The particular proportions for any formulation, however, are
selected in consideration of such factors as the intended
adhesive application of the composition, the desired properties
of the composition for such applications, for example, "quick
stick," adhesiveness and cohesiveness, and the particular
elastomer and terpolymer utilized. Usually for most pressure
sensitive adhesive applications, t~e terpolymer of this inven-
tion can constitute from about 20 to about 80 weight percent
of the adhesive composition with an amount of from about 40
to about 70 weight percent being preferred. Similarly the
elastomer component can constitute from about 20 to about 80
~ ,.
weight percent of the adhesive composition, with an amount
of from about 30 to about 60 weight percent being preferred.
If desired, the adhesive compositions of the invention can ;
contain other materials conventionally employed in pressure-
sensitive adhesive compositions such as plasticizers, fillers ;: ;
and antioxidants. `
The pressure-sensitive adhesive compositions of this
invention can be prepared or formulated by employing conven- ~
tional techniques. One typical procedure for preparing these -
compositions and especially those intended as a coating for
flexible su~strates to form pressure-sensitive adhesive tapes
,
involves first forming solvent mixtures of the elastomer and
3a the terpolymer admixed in the desired weight ratio. The
solvent mixture is then applied to a substrate employing
., . ~
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,4 '
",' ,, ~' ' , "' ~ , . .' ' ' ' ,
i~5'~946
standard coating techniques such as casting followed by drying
to remove the solvent.
The terpolymers of Example 1 were utilized to prepare
pressure-sensitive adhesive compositions by blending the
respective terpolymer with an elastomer and the compositions
thus produced were used to form pressure-sensitive flexible
tapes according to the following procedures:
Natural rubber stock (No. 1 pale crepe) was milled
to a Mooney viscosity of 5~ and was then dissolved in heptane
to provide a concentration of 15 percent solids. This solution
was then combined with the appropriate amount of terpolymer ~
dissolved in heptane to provide a 1 to 1 weight ratio of ter- -- -
polymer and rubber in the combined mixture. This mixture
containing terpolymer and rubber elastomer was then applied
to a thin flexible tape (~Iylar, 1.0 mil). The coated tape
was then dried to provide a solvent-free film thickness of
- 1 mil. The dried tape was then subjected to certain tests
to demonstrate the pressure-sensitive adhesive properties
of the composition of this invention. The results of these ;
tests are summarized in Table VI. The tests employed were ~- --
conducted according to the standardized tests promulgated
by the Pressure Sensitive Tape Council, Glenview, Illinoi
U.S.A. These tests were:
P.S.T.C. No.
Peel Adhesion 1
Quick Stick 5
Holding Power 7
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., ,
,"' .
105'~946
TABLE VI
Peel AOhesion
180 F. Quick Stick Holding Power
Polymer No ._ oz . /in .oz . /in . hours
1 39 28 287
2 40 30 182
3 40 21 188
4 36 22 - - -
7 23 28 - - -
8 21 14
9 42 12 ---
27 11 ---
11 45 46 195
12 18 12 ---
13 49 45 158
; 14 12 10 ---
lQ ---
16 25 9
17 12 8 ---
18 10 7 ---
21 41 46 136
24 40 37 -190
54 49 146
26 .54 . 35 190
27 46 44 154
28 43 43 150
29 6 2 200
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