Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~23~
¦ BACKGROUND OF THE INVENT
Field of the Invention
_ .
This invention relates to emulsion polymerization a-
particularly to an emulsion polymerization process which prove s
a stable, aqueous polymeric latex, the dispersed polymer phase
comprising particles having an inherently reinforced core-shel~
structure.
The invention further relates to lattices produced b;
such a process and adhesive articles prepared with such Lutz,
Description of the Prior Art
Pressure sensitive adhesives to be effective should
have good modulus properties, e.g. cohesive strength, as well
as adequate adhesion to a variety of surfaces. Many of the
monomers typically used in preparing adhesive lattices, often
require the incorporation of less tacky, but relatively high
modulus monomer materials, also referred to as high Tug resin
forming monomers.
I Increase in polymer modulus is often at the expense
Jo of the essential tack and adhesion properties. The use of coy-
sensating auxiliary tackifiers may be necessary; however, the
use of these materials may entail significant risk of lattice d sty-;
abilization, impairment of essential modulus properties or alto-
lion in the aging characteristics, e.g. US stability thereby
-I ., .. _ .. ,,.. , .. _- . 1
I
proving largely self-defeating. Generally "nodulus-enhancing
monomers, e.g. methyl methacrylate, styrenes acrylonitrile,
and/or methylacrylate, are included with the latex forming
monomer system e.g. copolymerizable acrylates, and thus
becomes incorporated into the acrylate polymer chain. The
amount of methyl methacrylate or other high Tug resin forming
monomer used for such purposes is usually and necessarily quit-
small to avoid or minimize detackification of the product late.
Objects of -the Invention
Thus, a primary object of the invention is to provide
an emulsion polymerization process, product lattices produced
thereby and adhesive elements prepared with such lattices where n
the foregoing and related disadvantages are eliminated or at
least substantially mitigated.
Another object of the invention is to provide such _ I
process capable of producing a product latex having good
stability, adhesion and modulus properties.
¦ Ye-t another object of the invention is to provide
¦ such a process enabling the use of relatively large amounts ox
¦ reinforcing, high modulus monomer for adhesive latex formation
with little or no adverse effect upon essential latex properties,
e.g. viscosity.
Still another object of the invention is to provide
¦ such a process enabling the preparation of latex particles hat- no
I an inherently reinforced structure.
other objects and advantages of the invention, will
¦ bikini apparent us the description proceed
1.
- 2 -
~236~34
The foregoing and related objects are attained in
accordance with the invention which in its broader aspects pro-
vises an emulsion polymerization process for preparing an awakes,
stable, polymer latex composed of emulsified particles comprise no
an inner or core phase of high Tug resinous polymer and a polemic
outer or shell phase integral with said core phase comprising
contacting at from about 50 to 85C, a dispersion of core phase
particles prepared from the emulsion polymerization of one or
more high Tug resin-forming mono-olefinic monomers with one or
more addition-polymerizable, shell phase-forming monomers, at
least about 60% thereof comprising acrylate monomer, in the
presence of an effective amount of polymerization catalyst and
a stabilizing amount of emulsifying agent to produce a product
latex of 40 to 60~ solids, the weight ratio of total shell foe- j
monomer to core phase particles being from about 3:1 to 10
a pi of 2 to 8 being maintained throughout the process.
In further aspects, the invention comprises the
product of such processing and adhesive structure prepared
therewith.
It is essential -to the reinforced shell-core
particle structure discussion herein that the acrylate monomer
phase undergo emulsion polymerization in the presence of
a preformed, emulsified dispersion of core particles the
latter preferably having been prepared via an emulsion polyp
merization process and more preferably by such a process
employing stabilizer and catalyst identical with that used
_ but no restricted to that in the ~Tglnte mollolncr, i.e.
'I I 34
shell phase polymerization. In certain embodiments to be ox-
planned in detail, the core phase particles comprise both
polymer and sub-polymer species corresponding to partial e.g.
about 20% and higher, conversion of high Tug monomeric reactant s.
Owing perhaps to increased reactivity levels as well as molecular
weight distribution of the product acrylate-partial polymerizate
contacting is capable of producing a product latex having high
shear properties, the latter being particularly manifest with
specific types of emulsifiers to be described in detail. In
lo these embodiments, shell phase monomer in the initial states of
the polymerization process is relatively rich in the core
monomeric material, the latter being a mixture of polymer, monomer
and partial polymerization as indicated. Accordingly, amount_
of polymeric product resulting from the reaction of the core
monomeric material is found as a uniformly dispersed phase in
the shell portion of the product latex particles. Whether thy
core particles available for interaction with the acrylate
monomer phase be fully or partly polymerized at the time
acrylate phase polymerization is initiated, and the invention
includes either embodiment, the core portion comprises a
uniformly dispersed phase, this being clearly observed by the
bluish cast of the dry polymer film when cast onto l mix MYLAR--
and analyzed via light scattering (Tyndall effect).
Without intending to be bound by theory, it appear
that due to polymer chain entanglement and/or grafting and/or
1~:36234
other stable bonding mechanism, the respective core and shot:
phase polymerizates at least at their common interface port
become uniformly and mutually dispersed. The high go core phase ¦
thus reinforces the acrylate phase, the total structure being
regarded in a sense as a "quasi" block copolymer, thus again
being indicated by light scattering analysis. Regardless ox
the bonding mechanism actually involved, the outer shell phase
becomes integral with the core phase in the manner described
thereby providing a stable latex product favorably characterized
for various adhesive uses.
Other criteria relevant to the process in general end
deserving of brief mention at this point include manner of monomer
addition, i.e. directly or as an aqueous pre-emulsion with one
or more other ingredients such as catalyst and monomer; catalyst- I
emulsifier system, to., amount and type as factors in determining !
specific properties of the latex product; type and amount of
shell phase monomer vis-a-vis core phase particles; pi values
best conducive to effective stabilizer function and catalyst
type and amount as factors in determining optimum modes of
ingredient contacting within the reaction vessel.
As will be made evident, one or more of the alone-
mentioned criteria can be determined in a given instance to
enhance specific properties ox the product latex, e.g. adhesion
to steel, polyethylene and the like, shear resistance for
SMACNA tape applications, etc. In all cases, the invention
provides polymeric lattices useful for transfer tapes.
_ 5 _
. _ , ... ",,
1~:3~i~3~
The "seed" polymerization method described herein
affords significant advantage over "non-seed" systems wherein
all Monomer is provided as a single phase, i.e. wherein all o
l the instant core monomer would be included as a component of
the acrylate phase. In the latter case, a core-shell structure
is not obtained as demonstrated by actual experiment. Con-
¦ sequently, one of the signal advantages of the present invention,
i.e. core reinforcement of shell phase polymer, is not obtainer.
¦ In the present method, greater proportions of core monomer,
! based on total amount of acrylate monomer can be used to en hare
the modulus of the latex product via the aforedescribed rein-
I for cement mechanism, with little or no adverse effect on latex
¦¦ viscosity and stability, the latter primarily connoting the
If capacity of the latex to retain its dispersed structure for
¦ prolonged periods absent of significant coagulum formation.
¦¦ Thus, the product latex is generally low in floe and possessed
! of viscosity fully compatible with commercial adhesive applique-
¦ lion. Typically, the product has enhanced cohesive strength
¦, as measured by standard corrugator lap splice testing as
I described in U.S. Patent 4,204,023; and is capable of forming
high-strength adhesive bonds with a variety of surfaces though
¦ applied as a relatively thin film on -the order, for example
0.7 mill The adhesive bond may be further enhanced with the us
of commercial -tackifiers such as Formal Emulsion Tackifiers and
the like.
~36~
Monomers suitable for shell phase polymer formation.
generally include one or more addition-polymeriznble moo- ¦
olefins, at least 60% and preferably at least 75/o by won't of
any monomer mixture comprising acrylate monomer, any reminder
being composed of copolymerizable polar monomer such as acrylic
acid (AA) and/or self-curing monomer such as isobutoxymethacry_- l
aside (IBM), the latter in amounts up to about I and proofer ¦
about 0.05-0.5% by weight of the shell phase monomer mixture
Particularly preferred for purposes of preparing pressure
sensitive adhesives are monomer mixtures comprising at least
about 75% 2-ethylhexylacrylate with up to about: 20% ethylacr;~- ¦
ate; 5% methyl acrylate and 5~Q acrylic acid. The alone-
mentioned acrylate inherently form solid, tacky-soft polymers
as is known in the art. Other useful acrylates generally come ,
prose the esters of acrylic acid and primary and secondary alkalis;
containing about 4 to 12 carbons. The polymethacrylates are
generally less tacky and of a relatively rigid, rubbery texture
or feel and in this sense tougher than the corresponding polyp
acrylates. Methyl methacrylate (MOE, for example, up to about
6% of the shell monomer phase, can be used if desired to increase
the cohesive strength of the product polymer latex.
Emulsifiers useful as stabilizers herein generally
comprises amphoteric, or anionic materials of-ten referred to a
surfactants. In some cases, the stabilizer may have both
anionic and non ionic moieties as with certain anionic/nonionic
sulfosuccinates available commercially, e.g. the material
. available from American Cyanamid Co. as AEROSOL 501.
e try
- 7 --
~36~
g573-2
Preferred stabilizers include (A) the half Malta reaction
product of malefic android (MA) with an ethoxylated, C10- C16
linear alcohol or ethoxylated alkyd phenol, e.g. octal or nosy-
phenol containing 4 to 9 moles condensed ethylene oxide, the half
Malta having the formula: HOOCCH=CHCOO(CH2CH2-O)xR, R being
linear C8- C30 alkyd or the moiety Al being O-, n-
or p-octyl or nonyl and x is about 4 to 9 and n is 1 to 3. These
half Maltese are prepared by reacting the indicated materials at
from about 80 to 100C in a bulk, solvent free system usually in
equimolar reactant proportions (B) ethoxylated alkali metal e.g.
sodium or potassium or ammonium Cog to C18 alkyd ether sulfates
containing 2 to 15 moles condensed ethylene oxide, e.g. the
ethoxylated (3 moles) sodium tridecylether sulfate supplied as
SIPEX EST* by Alcoholic Chemical Co., (C) the reaction product
of malefic android, decal to C4) alkylaminoethanol, sheller-
cetamide, and ammonium C8 to C28 alkyd sulfate as described
in U.S. Patent 3,925,442 being an amphoteric species and (D) an
anionic/nonionic sulfosuccinate such as aforementioned AEROSOL
501. The stabilizer is used in relatively small quantities
effective in any event to stabilize the latex product, their
proportions ranging generally from about 0.5 to 6 phi (parts per
hundred parts monomer). Optimum proportions in a particular
case have reference, for example, to the type of emulsifier
the pi of the core particle
* Trade mark
~3Çi2~3~
was well as shell monomer phase, the type of catalyst used, i.e.
ionic vis-a-vis non ionic or tonically inactive species, as
was properties desired in the product latex. However, primary ',
lemphasi_ attaches to phi _
Thus the pi selected should in any event be substantially nun-
interfering with respect to the stabilizing as well as other
functional effects of the emulsifier. For example, in the case
of the half Maltese (A), it is generally recommended that toe
pi in the reaction medium, and Or course, in the shell monomer
phase, be maintained at about pi > 5 0. As explained in t;-
referenced cop ending application, the half Maltese become i--
creasingly less water soluble below the stated pi value which
can impair their function. With certain monomers, greater
latitude is permitted as explained in the cop ending application
In general, emulsifier proportions and pi of -the reaction Mom,
for best results, are as follows for the (A) - (D) captioned
emulsifiers
pi proportions (ohm)` )
(A) 6 to 7 3 -to 6
(B) 3 to 7 2 to 4
(C) 2 to 4 2 to
(D) 3 to 5 0.5 to 1.5
As used herein, the term stabilizing amount is to b
accorded a significance consistent with the foregoing.
Cat~ly5LIl site for initiating slyly flus
(a) based on Illollolllcr (core or shell) Rosetta in phase exiled
__ tonal sty cry
, . ., . , ..
36,~3~ :
polymerization of the acrylate monomer system under the conditions
scribed are well known in the art, preferred species including
the pyre type e.g. t-butyl hydroperoxide (~BH~-90) supplied
for example as a 90% solution and alkali metal per sulfates, e.g.
5 potassium per sulfate. Catalyst amounts are usually quite small
and need only be that effective to initiate the polymerization
reaction such amounts generally ranging from about 0.2 to 0.4
phi (shell or core monomer phase). Particularly effective
results are obtained with the use of a co-catalyst reluctant
usually provided as an aqueous solution. In the case of per-
Sulfate initiator, a small amount of sodium bisulfate solution in
amounts providing a owe to 1 weight ratio with per sulfate is
recommended. In the case of TBHP initiator, a sulfoxylate
reluctant system comprising for example Phony so) owe and
NaS02CH20H.2H 0 in amounts providing, respectively, a 0.005:1 to
0.01:1 and 0.5:1 to 0.8:1 weight ratio with TBHP is recommended.
Temperature for shell phase polymerization ranges from about
1160-75C.
Al Core phase particles useful herein are obtained by
Thea emulsion polymerization of one or more high Tug resin forming
Mooney olefinic monomers including, without necessary limitation
Sterno, methylmethacrylate, acrylonitrile , vinyl chloride ,
l methylacrylate and the like, with preferred polymerizates
derived from the polymerization of styrenes and/or methyl
Imethacrylate. In particular preferred embodiment styrenes
__ comprises the total core monomer.
I Al
. The core phase emulsion polymerization is preferably
carried out utilizing emulsifier, a catalyst reluctant, etc.
identical with that to be employed in effecting the shell phase
polymerization. Proportions of these materials on the basis
of total core phase monomer are about equivalent to those desk
_ cried for the shell phase polymerization. Decreased amounts
are involved of course since the amount of core phase monomer
constitutes but a fraction of -total shell phase monomer. The
selection of pi in a particular instance is based essentially on
the relevant governing criteria discussed in connection with
shell phase polymerization. Polymerization is best effected
at from about 60-75C, although in most cases, operation within
the lower 60-65C range is adequate and particularly with styrenes
monomer. As indicated previously, relatively large amounts of
core phase monomer can be effectively used herein enabling
correspondingly greater realization of the favorable modulus
¦ characteristics inherent in such materials and -thus greater
shell phase reinforcement. The ratio of total shell phase to
Tuttle core phase monomer, or alternatively core particles herein
ranges from about 3:1 -to 10:1 with a range Of 5 1 to 8 1 being
preferred.
Optional ingredients to achieve particular effects
,' include FORMAL, a well known tackifier and DAXAD-ll~ a dispersant
comprising the sulfonated reaction product of formaldehyde and
naphthalene and supplied by Dewey and Army, Div. of W.R.Grace C.
_ .
I.
7.
FOAL enhances the latex adhesion property, i.e. increases its
adhesive aggressiveness, whereas ~XAD-11 generally reduces floe
levels. However, care should be exercised with the latter
material since it may tend, in some cases, particularly when
_ I used with AEROSOL 501 type stabilizers to reduce the shear
properties of the product latex, perhaps due to a reduction in
particle size and thus molecular weight of the latex polymer.
Generally, shell phase polymerization is effected by
adding monomer, catalyst, reluctant stabilizer, etc. to a pro-
. ¦ formed emulsion of the aforedescribed core particles, with any
1 required pi adjustment being effected by addition of base such
as ammonium hydroxide. In most cases, monomer, emulsifier and
i catalyst (excluding reluctant which is separately added) are
combined as an aqueous pre-emulsion (2.5:1 to 3:1 water) for
addition to the polymerization reaction mass. -
_ . _ _ _ _
¦ Also, total catalyst, monomer, stabilizer, etch may be
j, initially charged or added sequentially at predetermined intervals
Al throughout the course of the polymerization. One such procedure
Found to be effective particularly in the case of per sulfate
I initiated core and shell monomer systems involves continuous
i addition of monomer and catalyst, preferably non emulsified over
, the course of the reaction, with stabilizer being added at Lowe or
623~
3/4 of total monomer feed in equal portions.
Shell phase monomer is contacted with emulsified core
particles when the latter has achieved a degree of polymerization ¦
_ corresponding to at least about 20% conversion of precursor
monomeric reactants. In actual runs, it is found that half
Malta (A) as well as ethoxyla-ted alkyd sulfate (B) stabilized
systems utilizing TBHP catalyst and proceeding as described
generally produce substantially fully polymerized systems
approximately one hour after polymerization commences. Under
similar conditions, an AEROSOL 501 stabilized system exhibited
only about Roy conversion. However, shell phase polymerization
effected in contact with the partial polymerizate is found to
produce a shear resistant latex and thus comprises a valuable
aspect of the invention.
To assure high conversion and formation of a fully
polymerized latex product and particularly with emulsifier
(B) and (C) - stabilized systems, post catalyst addition may be
advisable wherein a small amount of catalyst and reluctant,
constituting about 0.01 to 0.1 of that added during the
core-shell forming polymerization, is added to the reaction
mass ingredients approximately 1/2 hour after completion of
said major polymerization. In this manner, unrequited monomer
or sub-polymer species is confined to a minimum if not eliminated.'
.
I-t would be understood that core-phase polymerization
is pry fireball effected in accordance with the criteria ~ove~nln~
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I 1
shell phase polymerization as to pi ingredient proportions
process temperature and the like. It is conceivable that the
core phase particles might be produced utilizing stabilizer and
catalyst differing in type and amount than used in the shell
phase polymerization or vice-versa. It is further conceivable
_ that such core particles might be obtained by post-emulsification
of a polymerizate produced by other than an emulsion process.
However to attain those beneficial effects unique to the inter-
phase coxswain of the ingredients herein specified, it is
recommended that each of the core and shell phases be provided
- in the manner described. ¦
The following examples are given for purposes of
illustration only and are not to be considered as necessarily
limiting the scope of the invention. All parts are by weight.
(A) stabilized systems are evaluated in examples 1-10 for effect
of pi and stabilizer levels on latex floe and conversion (Table l)
as well as effects of: scalp, examples 7 and 8 (Table 2);
increasing seed polymer concentration (example 9); using polyp
I methylmethacrylate as the seed polymer (example 10); adhesion
properties of transfer tapes prepared with the tested lattices
(table 3); corrugator lap splice testing (table 4); adhesion
to polyethylene (table 5), both tackifier loaded and non-loaded
samples being tested; comparison with non-seeded polymerizates
(table 6) and SMACNA tape utility.
- 14 -
I
l l
.
34
EXAMPLE
Core or seed phase particles are obtained by polyp
meriting the following compositions:
Parts
(2)
l Styrenes 15
H 0 62.75
Stabilizer* .75
DAXAD-ll .50
TBHP- 90 .0273
Phonies) .000197
** reluctant
10 Naso2cH2oH-2H2o ) .02
¦ at a temperature of 60-65C, pi being adjusted to 6.3-6.5 with
NH40H. A conversion of 53.5% is obtained in 1/2 hour and 100%
conversion in 1 hour. The latter latex sample is taken for use.
' A shell phase composition is prepared as follows:
arts
I (b)
j 2 ETA ) 80
¦ HA ) 16
I MA ) 1.9
AA monomer 2.0
)pre-emulsion
IBM ) .1
H20 ) 35
Stabilizer of (a) ) 5
I TBHP- 90 ) .18
¦, essay 2 )~eductant .n01l'
¦ 2 2 2 solution .12
~2 15
_
, i Jo I
362~
k
*Reaction product of malefic android and Tergitol~,15-S--5
............ ... unwon Carbide) - ethoxylated (5 moles) linear C - C alcohol.
**Sodium Eorm~ldehyde Sulfoxylate (IFS)
Shell phase polymerization is effected at 60-70 C by
- 5 first forming the monomer pre-emulsion consisting of the monomer,
stabilizer, and catalyst (oxidant). The monomer pre-emulsion
and reluctant solution are then added continuously over 11~ to 2
hours, pi being maintained at 6.3-6.5 throughout. The ratio of
total shell monomer to core monomer is 100:15. A stable latex
product with negligible pre-floc formation, is obtained wherein
a majority of the particles comprise the aforedescribed core-
shell structure, the core layer comprising a uniformly
4 dispersed phase as indicated by light scattering analysis.
Testing of the late indicated good adhesion to polyethylene
and steel.
EXAMPLES 2-6
The effects of pi and stabilizer concentration on
the stability of the reaction are tested. Example 1 is
repeated with pi of the core and shell phases as well as
stabilizer concentration (shell phase) being varied as
indicated. The results are summarized in Table 1.
, 1,
,
I
I ,
TABLE
Example No.
2 3 4 5 6
Stabilizer cone. 4 4 4 5 6
Core pi 8.5 7.2 owe owe 6.3
Shell pi 7,7 7.3 6.1 6.1 6.3
% floe 1.3 2.6 3.6 nil nil
% conversion > 99 >99 >99 ~99 >99
At 4 parts stabilizer (En. 2-4), floe levels decrease
with increasing phi However, at high pi (En. 2), floe level is
still relatively high.
Increasing stabilizer concentration from 4 to 5
phi significantly reduces floe (3.6 to nil) at the same phi
Examples 4 and 5). Floe level thus seems to be more sensitive I
to stabilizer concentration than to pi within the limits tested. ¦ ¦
In all cases, conversions of ~99~0 were obtained.
EXAMPLES 7 and 8
Example 5 is repeated but scaling up to 10 gallon
(En. 7) and 200 gallon (Ex.8) reactor runs respectively with
he Lyon results.
~3~2~
TABLE 2
En. 7 En. 8
% Solids 51.6 51,9
% Conversion >99 ~99
% floe nil nil
RUT Brook. Visa.
#3 @ 10 rum 3500 cups. 3840 cups,
#3 @ 20 rum 2165 cups, 2325 cups,
#3 @ 50 rum 1202 cups. 1266 cups.
Increased batch size apparently has little or no
effect on latex viscosity suggesting no appreciable change
in latex particle size distribution. The system thus
appears to tolerate at least the necessary, stabilizing
amounts of emulsifier.
The effects of increasing the amount of core, ire,,
reinforcing monomer in the seed or core phase is evaluated in
Example 9.
EXAMPLE 9
Example 5 is repeated but increasing the styrenes core
polymer concentration to 30 phi based on shell phase monomer.
The product latex (49% solids) indicated 99% conversion and a
5.1% floe level. As indicated in Table 3, physical properties
of the related product were not adversely affected by the
increase in core phase concentration.
- lo -
I ~36~3~
As indicated in Example 10, polymethyl methacrylate
can replace polystyrene as the core phase polymer without
appreciable adverse effects.
EXAMPLE 10
Example 5 is repeated but employing polymethyl-
methacrylate as the core or seed polymer. The product latex
(51.3% solids) indicated 98~ conversion and nil floe, Properties
(Table 3) are equivalent to those obtained with the polystyrene
core.
Samples for transfer tape testing and adhesive evil- ¦
lion (Table 3) are prepared by hand casting the latex products
of examples 5, 9 and 10 onto release paper and Mylar base
followed by air drying and curing for 1 minute at 30QF.
Samples -thus prepared provide a film which was found
to have a modulus sufficient to maintain film integrity during
slitting and application. When the tape (polymer film) is
attached to a substrate followed by lifting the film with the
liner removed, the polymer film broke cleanly with little
elongation, i.e. no rubber band effect. This clearly shows the
improved film modulus of lattices prepared in accordance with
the invention.
Transfer tapes prepared from the latex of Example 5
ore produced on the pilot spread line
- 19 -
. ~6~3~
The latex was evaluated with and without Formal WOW tackifier
(30 pup). The latex viscosity was adjusted using Reich hold
OWE latex thickener (5.3 mls/lb. of latex). Compounding
with the Formal WOW emulsion, increased the aggressiveness
of the adhesive to the release paper, alloying the use of normal
score slitting. The preferred product was produced with the
Formal compounded latex system (sample (d) table 3.).
TABLE 3
Adhesive Properties Or Transfer Tapes *
Ashes.
Latex Parts Sty- Parts Thick- Steel 150F
Sample of En. No. rhenium Formal 105 news Probe ozone Creep
-50~ Miss Tack His.
(a) 9 30/0 _ 1.2 15 100
(b) 5 15/0 _ 1.6 526 19 100~
(c) 5 15/0 30 1.6 893 46 100~ i
(d) 5 15/0 30 1.8 953 48 100~
eye 0/15 _ 1.9 15 100~ ¦
.
* adhesives laminated to 1 mix Mylar for testing.
** Applied stress of Gwen.
.,
"I . lo
Additional 10 gallon and 200 gallon batches gave
similar results. The tapes were also evaluated for corrugator
splicing properties using Allied Keynoter Raft paper. All
tapes passed the 10 oz/ir~,~olninute test at 150 C. Sample (d)
was also evaluated a-t greater stresses (Table 4) where the
time to failure, To, of the splice is presented.
TUB 4
Corrugator Lap Splice Test
Force, ozone To, Minutes
~60
~60
1.0
0.3
A tape product, produced with a mixture of emulsifying
agents comprising (1) a sulfonated diphenyl ether and (b) a
sulfonated reaction product of formaldehyde and naphthalene
such as described in U.S. Patent 4,204,023, was found in its
development to fail at 8 minutes under an applied stress of
18.75 ozone at 150 C. Thus, it is seen that the inherent
reinforced core-shell system possesses a greater cohesive strength.
At the same temperature approximately the same stress (18.75 vs.
20 ozone ), the present latex is superior by a factor of more than !
7-8 (time-to-failure) to the tape sample.
Adhesion to polyethylene is evaluated as follows:
The politely no utilized as the substrate ins 11.5 mix black
-21-
;234
IVISQ~EE~ film. The indicated latex was cast onto 4 mix Edison
polyethylene (R sheet), The results are summarized in Table 5.
TABLE 5
latex of
En. 5 -t Furl IS + Formal Ex.10 Furl ,
WOW 4202023 WOW WOW`
Thickness (miss) 2.2 1.91.6 2.01.8 2.0
Ashes Black
Visquem (02/in) 20 31~ 8 15 21
Ashes. Backing
(ozone) 20 45 8 _ _ _
Ashes. Glass
(ozone 20 I 24
Adhes.Steel
(ozone) 31 57 23 29 12 36
The above clearly demonstrates the superior adhesive
properties of -the instant latex compositions and particularly
those as embodied in Example 5. The somewhat inferior adhesion
of the non-tackified MA (Example 10) suggests perhaps a somewhat
high intimacy of the shell and core MA polymer portions. It might ¦
therefore be concluded that an abnormally high content of the
non-tacky resin polymer is dispersed in the shell portion and/or
is positioned within the shell phase in such manner as to partly
displace the tack effects of the polyacrylate.
a tackifier @ 30 pup (parts per hundred parts of total latex
polymer)
- 22 -
I .
_ l if
3~2~ 1
I; .
¦ my demonstrate its enhanced adhesion to polyethylene,
the insight=_ core-shell lattices are compared with non-seeded
systems.
_ the Example 5 latex tested as reported in connection
with Tab 3, is used as the basis of comparison. A latex
sample it --eared solely from the shell phase composition
of Exempt_ I, i.e., excluding the core phase composition entirely.¦
A third lox sample is similarly prepared employing the follow-
in as thy axle monomer composition, wherein the styrenes employed ¦
10 - as the Cove monomer is merely added to the acrylate monomer phase
to produce compositional equivalent.
Monomer Parts
EYE 69.6
Styrenes 13.0
HA 13.9
MA 1.6
AA 1.8
IRMA 0.1
The samples are designated 6-1, 6-2 and 6-3 respectively in
Table 6.
Each of the samples was cast onto polyethylene and
slated for physical properties.
- 23
~2~23
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-24_
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The non-seeded polymers in samples 6-2 and 6-3, the
latter in particular are clearly seen to have lower adhesion pro-
parties than the example 5 polymer. Apparently, with the 6-3 ¦
sample the air-polymer interface is influenced by the dispersed
5 polystyrene, which perhaps affects the contact angle, i.e.,
wetting of the polyethylene.
An important aspect of the present inherently reinforced
core-shell structure is that the adhesion property (steel) is
superior to the acrylate phase, sample 6-2 and the non-seeded
10- styrenes loaded acrylate phase, sample 6-3. Thus the present
system can contain a much greater percentage of a high Tug
monomer without losing properties, i.e. up to about 30 phi
(shell phase) Table 3 - Sample (a), as compared to the approximate-
lye 15 phi Or sample 6-3. As demonstrated, at the identical
styrenes loading, the present late is markedly superior.
The present lattices were found to possess high shear
strength when evaluated in the corrugator shear test as well as
high (30 ozone) adhesion to polyethylene. The polymer, however,
was lacking somewhat with respect to SMACNA* long term shear
requirements, holding less than the required 6 his. at a stress
Or 10 lbs/in2 @ 72l~
*SMACNA (Sheet Metal Air-Conditioning rational Association)
- 25 -
i
~36
Neither an increase of the IBM (isobutoxymethyl-
acrylamide) from 0.3 to 1.0 parts nor the inclusion of addition-
at styrenes monomer (1 part) to the shell phase caused an
_ improvement to the shear properties. Apparently, the molecular
weight and/or the distribution of the half Malta stabilized
polymer is inadequate to obtain the high SMACNA shear properties
required. I
The polymerization recipe for this class of
stabilizers designated (D) is similar to that employed with the
lo halt Malta (A) emulsifiers except for the use of lower
stabilizer quantities and pi levels in both core and shell phase
polymerization. In preferred embodiments as with the (A)
stabilizers, the same stabilizer, catalyst and reductants are
used in both core and shell phase polymerization.
In (D) stabilized systems, it is found at the start
of the acrylate feed, i.e., about one hour after initiation of
the core phase, conversion of the styrenes monomer is about 28%.
Thus, the shell phase is initially rich in styrenes diminishing
as the polymerization proceeds. It is hypothesized that this
structure as well as the polymer molecular weight distribution
contributes to the high shear properties of the (D) stabilized
polymer latex product.
if
_ 26 -
J
, _~.~
I' l
-- l
AL
,
The (D) stabilized system was found to be particularly
suitable for use in producing SMACNA and transfer tapes. Adhesion
to polyethylene were found to be moderate as compared with PA)
_ stabilized systems.
In the following examples both the core and shell phase
stabilizer concentrations are varied and effects upon conversion,
solids and floe levels (Table 7) and adhesion properties (Table I)
measured. Effects of scale up (Table 9), tackifier level (Table
. 10), the use of fully polymerized seed polymer (Table 11), Capella- ¦
per seed (Table 12), per sulfate catalyst (Table 13) are given as
ore transfer tape utility (Table 14) and polyethylene adhesion
(Table 15).
EXAMPLES 11-20_ ;
. I,
Core particles are obtained by polymerizing the
hollowing composition:
(a)
parts
Styrenes 15
H20 65.15
Aerosol 501 0.15
TBHP-~0 0.027
Phonies 2 0.000204
SO 0.02
~3~3~ 9573-2
at a temperature ox SUE pi being adjusted to 4~4~5 with
NOAH.
A shell phase composition is prepared as follows:
(b) parts
EYE 80
HA 16
MA 1.9 monomer
)pre-emulsion
AA 2.0
IBM Owl
~12 36 125
Aerosol 501 1.125
TBHP-90 0.182
Phony) SUE 6H2 0~00136)
IFS 0.12 ) Reluctant
solution
H20 15
Polymerization of the shell phase is effected by adding
monomer, stabilize Rand catalyst (oxidant) in the form of an
aqueous emulsion to (a), reluctant being separately added.
Temperature of the reaction mass ingredients is maintained at
65-70C
TABLE 7
11* 12 13 14 15 16 17 18
Cone Nero-
sol-core lo lo lo lo 1~171~33 1~0 owe 0~67 0~5
(phi)
Cone. Nero-
sol-shell
(Phi) lo lo l.125 1 125 1.125 1 125 1 25 l. 25 1 25 1 25
% Solids 48~6 47~1 46~5 47~844~0 47~2 49~3 48~3 47~6 39~0
% Con. 97~0 96~8 93~6 g6~990~5 99~6 99~0 36~6 99~0 91~0
% Floe 0~6 2~60~6 1~3 2~5 5~23~8 0~5 4~8 13~0
* 0.5 phi DOCKSIDE if
- I -
I
i
Low floe levels were obtained with the addition ox Dockside
(Example 11). With 1.0 phi Aerosol 501 in the shell phase, the
monomer pre-emulsion was not stable, breaking within 10% of
completion of the addition, unless mechanically maintained.
With increasing emulsifier concentration in the shill, and 1.0
phi in the core, the floe levelrexhibited a minim at 1.125 phi
in the shell. The floe level was found to increase with in- !
creasing surfactant concentration in the core, and a constant
concentration of 1.125 phi in the shell. Increasing the sun-
fact ant concentration in the shell phase -to 1.25 phi, a minimum
floe value was obtained with a concentration of 0.83 phi in the
core phase.
The various polymers were compounded with 60 pup Formal
WOW and cast onto SMACNA aluminum foil, air dried and
heat treated for Al @ 300F, Table 8.
TABLE 8
PHYSICAL PROPERTIES (VARYING SURFAC~ANT CONCENTRATION)
. Latex of Example No.
11~ 12 13 14 17 18
Cone. Aerosol-core 1.0 1.0 1.0 1.1 1.0 0.83
(phi)
Cone. Aerosol-shell
(phi) 1.0 1.0 1.125 1.125 1.25 1.25
Thickness, miss 2.1 1.8 0.7 1.9 2.0 1.9
Ash. Steel(oz/in) 84 87 65 64 88 71
hdh.Backing(oz/in) 79 89 90
Al Term Shear Fail Pass Pass Pass Pass Pass
(6 hrs.720F,10~/in2)
Lowe Tamp StJc~r Allah Pass rasp, l
(6 hrs.l50F,lll/in2)
Ion clown. S~lcnr Pass Pass Pnc3s
(6 ~II`5.40(~ Swahili)
Sport Tar Chicanery Puss Puss us - - -
(6 hrs.72F,5ll/in2)
* o . 5 porn Dockside 11
1 I
The polymers produced with Aerosol clue were found to
pass SMACNA specifications. The addition of axed to the
recipe, perhaps in part due to a reduction in particle size and
thus molecular weight, was found to decrease the shear properties.
Example 13, (1.125 parts surfactant in the shell phase) was found
to pass all the shear and adhesion SMACNA specifications even
though the coating thickness was found to be only owe miss,
Example 13 was successfully scaled up to a 10 gallon
run (Example 21) and repeated using post catalyst addition to
maximize conversion (Example 22). Post catalyst addition was
effected about 1/2 hour after commencement of the shell-core
polymerization using the following composition:
parts
IFS (Sodium Formaldehyde Sulfoxylate) .005
Water .5
TBHP (t-Butyl Hydroperoxide). .014
if
The lattices were compounded with 60php Formal 105-50~1 and
hand
cast onto aluminum foil. The results are summarized in Table 9.
TABLE 9
REACTOR SCALP
En. 21 En. 22
t Solids 45.6 49.5
% Conversion 91.2 99.0
to Floe nil nil
RUT Brook field Visa
I @ 100 rum 45 cups 46 cups
Thickness, miss 2.1 2.0
Ash. Steel, ozone 103 107
Ash. Backing ozone 94 97
Shear Adhesions Pass Puss
(SICKEN)
I
Example 21 was further evaluated on -the pilot spread-
line. The latex was compounded with 40, 60 and 80 pup Formal
105 and thickened with Reich hold (68-710) latex thickener,
The results are summarized in Table 10.
TABLE 10
EFFECT OF TACKIFIER LEVEL
Initial Axed* Initial Axed* Initial Axed*
Parts Formal 105 40 60 80
Thickness, miss 2.1 1.8 2.1
Ad Steel ozone 65 75 92 95 79 57
Ash. Backing, ozone 60 57 76 71 57 30
Laurel Term Shear Fail Fail Pass Pass Pass Pass ¦
Short Term Shear Fail Pass Pass Pass Pass Pass I
High Temp. Shear Pass Pass Pass Pass Pass Pass
Low Temp. Shear Pass Pass Pass Pass Fail Fail
* Aged 1 wok @ 150F/85% RHO
As expected, the shear adhesion proper-ties
were found to be dependent, in part, upon -the tackifier concentra-
lion, with 60 pup Formal wow graven optimum prewashes. I
Polystyrene latex was prepared in 9~+~0 conversion.
The preformed polystyrene latex was then used as the seed (15 phi)
for the standard shell phase polymerization. Aerosol 501, at
levels of 1.0 and 1.25 phi were evaluated, Examples 23 and 24.
The samples were compounded and tested for basic properties with
results ~iVe!l in Table 11.
- 31 -
.' I-
a ,
I ~;~3~3~ 1
. I
TABLE 11
EFFECT OF PREFORMED SEED LATEX
En, 23 En, 24
_ _
Parts Aerosol 501 1.0 1.25
% Solids 47,4 49,3
_ I Conversion 97 99
% Floe 2.2 0.
Ash. Steel (one) ox 83
Long Term Shear Fail Foil
The floe level was found to be greatly
diminished with the higher surfactan-t level 0.4 us 2.2%. Al-
though the adhesion values are equivalent to that obtained in
the in-situ synthesis, i.e. partially polymerized styrenes core
particles, the use of a preforrled seed latex apparently differs
in the polymer micro structure in that the polymers failed in
shear strength. Use of preformed polystyrene probably results
in less interaction between the seed and shell phases, Addition
of the acrylic phase to the insight polystyrene would find "live"
ire. reactive polystyrene chains and should therefore be in Q
more intimate relationship and leading to perhaps a greater
graft fraction (C-C bond as well as chain entanglement) and
thus higher shear (cohesive) strength,
Styrene-methylmethacrylate (8~/17) copolymer
was evaluated as the core phase polymer, example 25. The
concentration of Aerosol 501 was maintained at 1.0 and 1.125 phi
in the seed and shell phases respectively. The polymer was
found to pass -the screening properties (adhesion and lone term
shear) as the result, of Table 12 indicrlte.
- 32 -
Z3~
TABLE 12
EFFECT OF COPOLYMER SEED POLYMER
En. 25
Seed Stymie -(83/173
% Solids 47.4
_ % Conversion 98
% Floe 3.1
Thickness, miss 2.4
Ash. Steel (one) 77
Long Term Shear Pass
As in the styrenes core polymerization, the
Stymie copolymer of this example was found at the start of
the acrylic feed to have a low conversion, 36%.
2 2 8 3
grated using 1.0 phi and 1.13 phi of the surfactant in the core
and shell phases respectively. Relatively low conversion and
high floe values were obtained.
However high conversion polymer was obtained
in a system in which the monomer was not pre-emulsified, example
26. No pi adjustment of the batch was made. The polymerize-
lion of the styrenes seed (1.0 phi surfactant3 was initiated with
0.25 phi K2S208 and 0.2 phi Nazi. The monomer mix was then
added continuously, along with K2S208 solution (0.25 phi)
to the reactor. The surfactant (Aerosol 501) was added
incrementally during the shell phase polymerization at 1/4,
and 3/4 of monomer feed (0.5 phi each inaction). although
the floe level was found to be high (3.7,0)9 the properties were
evaluated for comparison purposes, Table 13. The adhesion-
shear properties were follnd no-t to be altered With either the
change in catalyst or polymerization conditions.
TABLE 13
EFFECT OF PER SULFATE INITIATION
En. 26
_ % Solids 47
% Conversion owe
% Floe 3 7
Thickness, miss 2.3
Ash. Steel ozone
Long Term Shear Pass
The Aerosol 501 stabilized latex system was
found to be suitable for the production of a transfer tape.
Example if, with and without Dockside if was compounded with 30
pup Formal WOW and hand cast on-to release payer.
The polymer film possessed sufficient strength to be useful in
a transfer tape configuration. Physical properties, including
the eon Tory splice test, were evaluated, Table 14.
TABLE 14
TRANSFER TAPE
AXAD-ll NO DAXAD-ll
Thickness, miss 2.1 2.0
Ash. Steel (applied
to l mix Mylar)(oz/in~ 43 36
Creep, 150F, Gwen 100+ Lowe
(his.
Corrugator Splice at
150C, 10 ozone Pass Pass
The lattices of Example-s if and 25 were tested
for adhesion to polyethylene using Edison R sheet (polyethylene
film) as the backing and designated samples 15-A and 15-B rest
I
~L~36~3~
pectively (Table 15~. A further latex sample (clue is prepared
solely from the shell phase composition of Example 11. Another
latex sample is prepared ~15-D) employing as the sole monomer
the composition of Sample 6-3 (Table 6). Each of samples 15-C ¦ .
and 15-D is cast on-to Edison R sheet (polyethylene film) as the
_ backing. Adhesion results are summarized in Table 15.
TALE 15
ADHESION TO VISQUEEN POLYETHYLENE
15-A 15-B 15-C15-D
Aerosol 501 (phm)1.01.125 1.125 1.5
Seed polymer StySty/MMA - j
Ash. Steel (ozone) 26 17 19 23
(~3Qphp Formal WOW 31~30 36
Ash. "Visqueen" (ozone 5 9 10 4
(+30php Formal WOW 17 19 14
The Aerosol 501 system was found to have little
adhesion to the "Visqueen" polyethylene. Essentially no
difference was observed between the seeded and unseeded polymers.
Thus with the Aerosol 501 system, the adhesions to the polyp
ethylene are apparently a "minimum" value depending upon the
polymer composition.
Lattices obtained with systems stabilized with
poly-ethoxylated-alkylether sulfates, as typified by SIPEX EST
comprising e-thoxylated (3 moles) sodium tridecylether sulfate,
when compounded with 30php Formal WOW, have polyethylene
adhesion proper-ties comparable to the (A) half-m~leate-sta~ilized
systems. The lattices are also useful for transfer tapes. Shear
properties, however, ore inferior to tile (1)) -sulrosuccil~ltc-
stabilized systems (Aerosol 501
:'
lo
~f~3'6~3f~
With these stabilizes, it is advisable to
include a small amount of the shell phase monomer - catalyst
(oxidant) - stabilizer pre-emulsion in the core phase monomer
composition to facilitate initiation of the polymerization I '
reaction. Usually, from about 1 to I of the shell phase pro-
emulsion is sufficient for such purposes. Thus, it is
found that initiation rapidly commences with the addition of .
1.7% of the shell monomer emulsion tooth seed charge.
Approximately 100% conversion of seed monomer is obtained within
1 hour after polymerization commences. The effect of pi on the
(B) stabilized polymerization process is evaluated in the
following examples.
EXAMPLES 27-32
Core phase particles are obtained by polymerize
in the following composition parts
1.7% of the Acrylate Emulsion of (b)
Sterno 15
H20 65.79
Swoop FST-30 0.338
TBHP-90 -~55
Phonies owe
IFS 4
at a temperature of 60-65C, pi being maintained at 4-4.5.
~3~2~3~
' A shell phase composition is prepared as follows:
parts
EYE 80
HA 16
_ MA 1.9
AA 2 ) monomer
) pre-emulsion
IBM 0.1
H20 40.25
Sipex EST-30 2.25
TBHP-90 ' 0.182
Phony) (S04) 6H 0 0.00136 )
IFS 0.12 Reluctant Solon ¦
2 15
Polymerization of -the shell phase is effected by
adding monomer, stabilizer and catalyst (oxidant) in the form of a
aqueous emulsion to (a), reluctant being separately added.
Temperature of the reaction mass ingredients is maintained at
65-70C.
The effect of pi on the polymerization was examined.
The samples were also evaluated for both SMACNA and adhesion
proper-ties, Table 16. The samples were compounded with 60 pup
Formal WOW for SMACNA, and 30 pup Formal WOW for polyp
eta adhesion.
- 37 -
- ,..
" Jo
Jo ' 1, I
I
TABLE 16 .
EFFECT OF pi ON SIPEX EST STABILIZED POLYMERIZATION
Example No.
27 28 29 30 31 32
pi 2,8 4.1 4.1 6.3 6.3 4~1
Sipex EST, phi 2.25 2.0 2.25 2.25 2.25 2.25
Seed Sty Sty Sty Sty Sty Stymie
% Solids 48~1 48.6 48.2 47~9 48.6 47.6
% Con. 99.0 99.0 owe 97.0 97.2 97.0
% Floe 3 3 o owe nil nil 0.3
SMACNA PROPERTIES
Thickness, miss - 2.3 2.4 2.2 - 2.4
Ash. Steel, ozone - 71 70 91 _ 64
Long term Shear - Fail Fail Fail - Fail
"VISQUEE~" ADHESION*
Thickness, miss - 1.8 - 1.8 1.8 2.0
Ash. Steel (ozone) - 23 24 26 20
t+ Formal) - 32 38 36 29
Ash. Visqueen (ozone) - 14 - 15 16 16
(+ Formal) - 22 26 26 29
*Compounded with 60 pup Formal lQ5-50W, cast orate S;ViACl~A
aluminum foil
I* Compounded with 30 pup Formal WOW, cast onto "EDISON R
SHEET" polyethylene film.
All samples -tested for SMACNA shear were found to have
inadequate strength indicating a different micro structure from
that obtained with Aerosol 501. The adhesion to polyethylene
was found to approach that obtained with the (A) stabilized system.
Essentially no effect was observed with respect to the composition
f t h e s e e d p o `. y I or (s t Irene vs. s t y rhenium copolymer).
-36-
I
AL 2 3 6 2 3
Example 29 was scaled up into the 10 gallon reactor
(example 33) and evaluated for adhesion, Table 7. 'amps were
cast onto EDISON R SHEET (polyethylene).
TABLE 17
Example 33
_ % Solids = 47.9
% Conversion 97.2
% Floe = nil
Pi = 4.1
RUT Brook. Visa. #2 @ 100 = 220 cups
Formal WOW Thickness, miss Adh.Steel Ash. "Visqueen"
(ozone) Pull ylene (o yin)
_ 1.5 30 17
1.5 31l 28
A latex sample, AYE, (Table 18) is prepared solely
from the shell phase composition of example 29. A further
latex sample, 18-B, is prepared using as the sole monomer, the
composition of sample 6-3 (Table 6). Each of the samples was
cast onto EDISON R SEPTET ( polyethylene with the following
results.
TABLE 18
EFFECT OF NON SEEDING ON PROPERTIES
18-A 18-B
Solids 50.2 43 .7
% Conversion 99.6 88.6
% Floe 0.3 owe
Ash. Steel (one) 17 18
(-~30 ply Twirl Lowe) 28 30
Ash "Visqueell (one) 10 12
(+30 pup Formal WOW) 18 1
- 39 -
~3~3~ ,
The unseeded polymers were found to decrease in
adhesion to polyethylene and to be equivalent to that obtained
with the Aerosol 501 stabilized polymers. As with the (A)
stabilized polymer, the present seeded polymer structure, perhaps
in conjunction with the ethoxylated surfactant, resulted in an
improved adhesion to polyethylene.
forts to analyze the (A, (B) and (D) stabilizer
systems with respect to latex particle size and gel-swelling
index proved to be inconclusive.
'i
All polymer systems were found to contain, within
experimental error, essentially the same gel-swelling index.
(65-75% gel and a swelling index of 30-45 as measured in Tulane
with a contact time of 24 his.). The particle size (Do) of the
various lattices were also found to be essentially equivalent,
AYE. The particle size distribution (not measured) is
nicety likely in variance as observed by the coloration of the
lattices (Tyndall). I-
EXAMPLES 33-37
Systems stabilized with (C) the reaction product
of malefic android, dimethylaminoethanol and chloroacetamide
mixed 1:1 mole ratio and ammonium laurel sulfate are evaluated
at stabilizer concentrations of 3 and 6 phi in the seed phase
and 1.5 and 3 phi in the shell phase. The results are
mmarized in Table 19. ¦
_ I -
I
TABLE I
(C) Stabilized Polymers - ;
Example No.
33 AL 35 36 37
Seed Polymer Sty Sty Sty MA MA
(C) (seed), phi 3 6 3 6 3
(C) (shell), phi 3 3 1.5 3 1.5
% Solids l~7.7 47,7 44.0 46.8 47.6
% Con. I 99 99 97 99
% Floe 2.3 on 9.8 1.9 owe
Ash. Steel (ozone) - 24 18 29 20
Creep 150F, Gwen (his.) - - 100~ - 100
Lap Splice, 150F
10 ozone - pass pass pass pass
do. Polyethylene (ozone) - I - 14 _
* Compounded with 30 pup Formal 105 - WOW
The floe level was found to be higher than that
l obtained in the prior examples. The polymer obtained way found
¦ to possess the improved modulus property and to pass the cargo-
Tory lap splice -test ( 60 min. @ 150F and 10 ozone).
Adhesion to polyethylene, however, was found to be relatively low.
There is no apparent difference in adhesion property with the use
of a styrenes or methylmethacrylate core polymer.
EXAMPLE 38
A posy (2EHA/EA/MA/AA-80/15/2/2)~ styrenes core
(15 parts), system was produced with 3 phi of the aforedescribed
(C) stabilizer in the seed and 6 phi in the shell. The self
cure monoiner - IRMA (isobutoxy-methacrylamide) is omitted.
- 41 -
-
L
I
The polymerization proceeded to full conversion with -
negligible floe formation. The latex was cast onto 1 mix Mylar
for evaluation of adhesion properties and release paper (transfer
tape for Corrugator Lap Splice evaluation, Table 20.
_ TABLE 20
PHYSICAL PROPERTIES OF NON CURING POLYMER
Example 38
Thickness, miss 1.5
Probe Tack 460
Ash. Steel ozone 28
Quick Stick (ozone) 18
Creep 150F gunners) 1.2
Lap Splice 150 F, 10 ozone Fail
The seeded polymer with no cure mechanism was found
to fail the Lap Splice test 1 hr. required). The polymer
did, however, have sufficient strength to produce a satisfactory
transfer tape. It is apparent that both the seeded structure
and self-cure monomer are required for optimum properties.
EXAMPLES 39 & 40
Employing a styrenes seed (7.5 parts) a (2EHA/VA/MA/AA-
65116.5/15.5/2~ shell polymer was produced using 3 phi of an (A)
type stabilizer comprising the reaction product of malefic
android and IGEPAL co-630 (GAY) - (9 moles ethylene oxide)
nonylphenoxy (ethyleneoxy) ethanol and the aforedescribed
I _ Ll2 -
~L~36234
sulfoxylate-hydroperoxide catalyst system, at a pi of 6 with
negligible floe formation, Example 39, An additional sample
was produced with a styrenes seed (15 phi) and with K2S20
catalysts. Approximately 10% floe was obtained (Example 40).
The two samples were evaluated for physical properties, Table 21.
-
TABLE 21
En. 39 En. 40
Thickness, miss 2.2 1~3
Ash. Steel (ozone 19 23
Quick Stick (ozone) 13 19
Creep 150F gunners) 100+ 100
Imp Splice 150F, 10 ozone - Pus 60 mix )
Both polymers were found to possess the higher
modulus required for use in a transfer tape configuration. The
polymer of Example 40 was found to possess good cohesive strength,
passing the lap splice test without a post cure. This clearly
shows that the properties (e.g. splicing) depend upon the "gel"
structure and/or composition of the shell polymer.
As indicated by the foregoing examples, the core-
shell latex structures stabilized as described herein, have
improved modulus properties with respect to both a non-seedcd
acrylic shell structure and the structure obtained by including
total core monomer in the shell phase monomer composition.
Regardless of the particular stabilizer used, the resulting lattices
are found to be useful in the manufacture of transfer tape without I
a reinforcill6 mcmbrQIle. The physical l~ro~crties ox` tic Q~CX
product are in part determined by the stabilizer used, particularly
~6~39;
5 regards adhesion to steel and polyethylene and SMACnA tape
utility. It Luther spears tot latex properties are in
large part determined by the composition of the shell phase,
although influenced to some extent by the composition of the
seed polymer. However, the composition of the core polymer
as well as stabilizer influences the adhesion to polyethylene
and steel.
The polymer product produced with Emulsifier (A
was found to be most useful when used to produce a diaper tape,
The tape so produced was found to be prepositional when tested
on disposable diapers yet to have sufficient holding power to
the out olyetnylene film to be serviceable, ¦ j
