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Патент USA US2404519

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Patented July 23, 1946 I
George Osman Morrison and Henry Michael
Collins, Shawinigan Falls, Quebec, Canada, as
signors to Shawinigan Chemicals Limited,
Montreal, Quebec, Canada, a corporation of
No Drawing. Application May 15, 1943, Serial No. .
487,186. In Canada November 4, 1942
3 Claims.
(Cl. 260-28) _
Example I
This example demonstrates a preferred method
This invention relates to emulsionsof polyvinyl
acetate and to protective ?lms and coatings
formed therefrom.
of manufacturing a polyvinyl acetate emulsion
. according to the invention.
In one procedure the following constituents
Polyvinyl acetate is particularly useful fur coat
were employed at the approximate concentra-_
ing purposes in view of its excellent ?lm-forming
tion. set out:
properties, freedom from ‘brittleness, good colour
and inertness to chemical in?uences. It is also
tough and ?exible and has many other useful
Water ' _____________ _‘____’_ ______ "grams" 800
' Vinyl acetate
characteristics. Its speci?c properties may be
readily varied to suit particular uses. I-Ipwever,
Emulsi?er-gum tragacanth ____ __per cent__ 1.25
Partially hydrolyzed polyvinyl acetate '
the use of aqueous emulsions of polyvinyl acetate
having a polyvinyl acetate content of
about 31% made from polyvinyl ace
for forming moisture-proof coatings has been
somewhat limited because of the sensitivity of 15
; tate having a viscosity of “ at 7 centi
these coatings, to re-pmulsi?cation andv cons:
poises _________________ __per cent__
quent disintegration,
“Aerosol O. T.” (the sodium salt of the sul
phonic acid of dioctyl succinic ester) ____
per cent__
It is a principal object of the present invention
1 20
to provide new compositions of matter including 20 Catalyst-benzoyl peroxide _______ "grams" .69
polyvinyl acetate emulsions which are suitable for
1 By weight of the total charge.
use in the preparation of waterproof sheets or
An aqueous solution of the emulsi?er was
?lms, or useful for forming waterproof coatings
charged into a kettle equipped with a re?ux con
on various materials. It is a further object of
the invention to provide a composition embody 25 denser and stirring blades. One type of equip
ment, as used according to the following condi
ing, in emulsion form, polyvinyl acetate as a ?lm
tions, includes an aluminum pot about 8 inches
forming constituent, and a moisture-proo?ng
high by about 6 inches outside diameterlhaving
agent with or without other modifying constitu
aconcave bottom and no baffles. The stirrer
ents such as for instance, softeners andlplasti
shaft is of stainless steel. It embodies half an
cizers. Further objects are to provide improved
inch from the bottom 4 blades in a cluster 1 inch
methods of making these compositions, improved
by 1/2 inch bent at 45° for downward thrust; four
methods of moisture-proof coating, improved
inches from the bottom, a pair of blades (one at
coatings and improved coated articles.
each side of the shaft) each 21/2 inches by 1%, inch
35 bent at an angle of 45° for downward thrust. The
useful speeds, of the blades are‘about 500 to about
These objects and others are accomplished ac
1800 revolutions per minute.
cording to the invention by a composition which
Stirring was started. The catalyst and water
includes an aqueous emulsion of polyvinyl acetate
as a principal ?lm-forming
were added. Two minutes, stirring at about 1200. ‘
constituent, an
oleag/inous or waxy protective agent, the composi 40 revolutions per minute was allowed and then they ‘
monomeric vinyl acetate was added slowly. The
tion being capable of forming a ?lm having
whole charge was then agitated for about 5—
moisture-proof characteristics. This ?lm may be
minutes in the cold to complete emulsi?cation
laid down by ordinary methods of coating, but
of the monomer. Stirring was continued at about
preferred results are achieved by ?ashing the ?lm,
(that is, by subjecting‘ it to a blast of hot air at a 45 the same speed and the temperature of the jacket
raised to about 70° C. and maintained at this tem- ‘
temperature above the melting point of the waxy
perature until the temperature of the charge
agent. This causes the formation of .a bloom
which protects the ?lm from re-emulsi?cation or
reached about 66° C.
from otherwise disintegrating.
Then, as the reaction gathered momentum and
re?ux commenced, the temperature of the jacket
was gradually and suitably reduced in order to
maintain a ‘moderate re?ux of about 1 percent, to
about 11/2 percent of the total charge per hour.
Articles made from materials which are not re
sistant to water and coated in this manner may
be rendered completely
in the case of
tainers for aqueous materials.
To illustrate the invention in more detail,
several examples will be given of speci?c embodi
Finally, the jacket temperature was reducedin
‘order to regulate the re?ux at the low rate. When
the temperature of the charge had reached about
‘70° C. the temperature of the jacket was gradu
allyraised from its minimum to about 82° C.
~ Thus, as the temperature of the charge increased,
ments. These data are intended in an illustrative
60 the re?ux slowed up and the temperature of the
- and not in a restricting sense.
charge followed closely behind that of the jacket.
two ?ne cardboard containers C and D substan
tially as in Example 2, at a temperature of about.
When they were equal at about 82° C. re?ux
. ceased and polymerization of the monomer was
substantially complete.
20° C.
A thin ?lm of wax was “slosh” coated over the
The wax was then added and the emulsion
stirred for about 10 minutes with the temperature '
maintained at about 82° C. The charge was then
dried polyvinyl acetate ?lm of container C at
about 90° C. Where there was no plasticizer
present in the polyvinyl acetate, the resultant
?lm was brittle.v The composite ?lm was made
cooled down to about 25° C. This was done over
a period of about one hour with stirring con
up of about 11/2 mil polyvinyl acetate and about‘
tinued. The agitator was then stopped and the 10 1/2 mil wax.
The container was ?lled with water which was
batch of ?nished emulsion discharged. The re
sulting composition had substantially the follow-‘
kept at about 30° C. After about two weeks the
container and ?lm were intact, but creasing of
ing characteristics:
Viscosity of emulsion at 20° C__centipoises__ 300
the cardboard . resulted in extensive leakage.
There was no re-emulsi?cation.
?iiiét?ltiai‘aaaa;;_11:'::_'_1';‘1‘iitii‘f:: 33
The ?lm 211 container D. wasallowed to dry
Polyvinyl acetate viscosity___centipoises____ 30
at about 20 C. Re-eniulsi?cation. of the ?lm
Stability .
began after about 1 hour 5 contact with the water
and the container collapsed after about 10 hours’
1011 total charge
l 20
contact with the water. -
Emmple 2
te the respective char-
‘1313:2211???’. . ind “?ashed” . ?lmsI
Example 4
emulsion was prepared as in Example 1 with
e exception that the waxy agent was increased
lald dOWn from a composltlon made according to
to about 60% of the polyvinyl acetate
A mm was as from this was.“ by sash"
asin?é‘stiieitiitln t‘?‘fé?litié?fgétitféé
gslaétiggng’niggug igldcé onTghegenéilgga?ggziegg
and the containers were subjected to the same
tests as in Examples 1 and 2 to determine their
made from ?ne 9ard1?°a?d of t’lte'type usually
ability to withstand ‘water.
The results were
emptoyed for making hqmd c9ntamers' Th? ?lm 30 similar to those obtained with the ?ashed ?lms
cgatmgothe surface of container A was dried at
° C.
of Examples 1 and 2 with the exception that the
The ?lm was about 1 mil in thickness. It was
pliable-and elastic. Water at about 30° C. was
,poured into this container. After about 72 hours 35
' at room temperature the container Was practi-
cally soaked through and had collapsed.
?lms of this example were more elastic.
Emmple 5
The procedure of Example 1 was repeated with
hydrogenated cotton seed oil replacing about 25%
of the para?in wax, the oil'serving as a, push
?lm had almost completely re-emulsl?ed_
cizer for the wax. From the resulting emulsion
The coating on container B was dried at about
a ?lm was formed on the Surface of the con
20° C. It was then “?ashed" for abqut three 40 tamer. The ?lm was ?ashed and cooled and
minutes in an air oven with a blast of all‘ heated
tests for moisture-proof characteristics were car
to about 110° C. The ?lm was about 1 mil in
_ried out substantially as in Example 2. The ?lm
thickness. It was Dhable and elastlc- A bloom
had the same excellent moisture-proof character
of wax had formed on the surface. Water at
istics as container B (Ex. 1) and was at the same
about 30° C. was poured into this container. 45 time more pliable and more capable of being
After about two weeks at room temperature the
creased without injury to the ?1m_
?lm on the container was still intact.
No re-
emulsi?cati'on of the ?lm could be detected.
Ea: m l
6 15
“ 1’ es ‘
tain'ers coated similarly to B were acceptable to
In 011191‘ to demonstrate the manufacture and
the trade for containing aqueous materials.
50 use Qf dl?erent ?lms formed according to the in
Exambze 3
vention, the following Examples 6 to 15 are
given. According to the natures and approxi
The following example demonstrates the charmate concentrations of the ‘constituents set out
- acteristics of a ?lm prepared from a polyvinyl ’
in the table, emulsions were made substantially
acetate emulsion containing no wax but subse- 55 in accordance with Example 1.
quently coated with wax.
Containers were
coated with these emulsions and tested for per
An emulsion was prepared substantially as in
Example 1 with the exception that no wax was
incorporated. A ?lm was cast on the inside of
formance substantially as in Example 2, and the
performance of the coatings was as indicated in
the table.v
Table I
_ Wax plasticizer
wa?ggfgég of
bility of?lm
Per cent
Nil ____________________________ _.
Petroleum jelly, 15% __________ __
Petroleum jelly, 20%..
Petroleum oil, 12%...-
---------------------- --
' ‘mgtssssntsts;gas-an;-
Petroleumjelly, 15% ____ ..'. ________ "do ....... __
100 ‘
Nil ____________________________ _- Very pliable.-.
_ . . . _ . _ _ _
. _ _ "do _______ __
* The coating of Example '6 was not ?ashed, whereas those of Examples 7 to 15 were ?ashed.
"3 G. H." is trlethylene glycol di-hexoate, M.
17 is methyl phthalyl ethyl glycolate and B. 16
of the container from the plasticizer. ‘ Thus the
concentration of the plasticizer may be increased
is v,butyl phthalyl butyl glycolate.
over what might otherwise be thought possible
without danger of contaminating the contents.
Example 16
The emulsion was made as in Example 1 with
the exception that the wax was added to the
While substantially conventional methods are
charge'before the start of the reaction.
employed in making ‘the emulsion, in order to
The emulsion was used for coating containers
improve still further the qualities of the emulsion
in procedures similar to those of Example 2. The 10 as a coating material, special steps are taken in
results as regards the characteristics of the ?lms
the process of manufacture. Up to the com
and their moisture-proof performance were sub
pletion of polymerization the procedure is con
stantially the same as those of Example 2.
ventional for the manufacture of polyvinyl ace
tate emulsions, with the exception that the waxy
15 agent is added as an additional phase either
While the examples demonstrate various
prior to, during, or after polymerization. The
speci?c types of coating-emulsions according tov
procedure then departs from the conventional
in that the wax-containing emulsion is cooled
the invention, it will be obvious to one skilled
in the art that the particular constituents, com
very slowly, i. e. over a period of about 40 min
positions, conditions and concentrations set out 20 utes to about 2 hours or more, from the upper
temperature resulting from polymerization of
may be varied widely within the scope of the
about 84° C. to room temperature of‘ about 20° C.
By following this procedure, emulsions‘ can be
Pao'rnc'rrvr: AGENT
made having viscosities of between about 200
For instance, the nature of the protective .25 and about 2000 centipoises. Those in the neigh
agent may be varied. Suitable agents are ole
borhood of 300 centipoises are preferred. These
emulsions ?ow readily, thus having excellent
aginous or waxy materials such as for instance;
hydrogenated natural oils and fats, for example,
characteristics for coating. In contrast, similar
cotton seed oil, linseed oil; saturated natural oils,
emulsions which were cooled rapidly, exhibited
for instance, animal oils, sperm oils; paraf?n 30 viscosities of as high as 7,000 centipoises. The
type oils and waxes, for example, micro-crystal
latter emulsions were not stable, and ?lms laid
line paraf?n wax and para?in oil; or mixtures
down from them were poorly flexible.‘ From this,
of these substances. These agents or mixtures
it would appear that slow cooling causes the for
mation of small discrete wax particles as a third
thereof should have a melting point of between
about 47° F. and about 140° F. and the neces 35 phase of the emulsion. In most cases, these wax
sary flexibility when solid and other coating
particles were of a size between about 4p and
characteristics as will be understood by those
about 2011..
skilled in the art. The melting point will vary
In general, the normal constituents of the
emulsions, e. g. emulsifying agents, catalysts,
depending upon the particular use to which the
coating is put. It is preferable that the melting 40 modifying agents, etc. may be those generally
employable in the manufacture of aqueous emul
point be between about 100° F. and about 140° F.
sions of polyvinyl acetate. Preferred types of
Preferred agents are paraf?n waxes.
The useful range of concentration of the pro
emulsions may, however, be manufactured by
following the teachings of the present application
tective agent is between about 12% and about
in conjunction with those of the following co
40% calculated by weight on the total charge.
The preferred range of concentration is between _
about 12% and about 20% .
Monrmrmc AGEn'rs
The coating emulsion is preferably modi?ed to
make the resulting ?lm/ more ?exible and to
render it more ?owable than it would be with
wax alone as a protective agent. This may be
effected by adding a softener for the wax and/or
a plasticizer for the resin. An effective softener
is hydrogenated cotton seed oil, conveniently the
commercial product known as “Crisco,” employed
at concentrations of between about 3% and about
15% of/lthe total charge. Other oleaginous soft
pending applications, _H. M. Collins, S. N. 457,337,
Sept. 4, 1942, relating to the use of emulsifying
agents of particular types, and M. Kiar, S. N. ,5
457,339,‘Sept. 4, 1942, relating to the use of par
ticular conditions to in?uence the characteristics
of the resulting polyme .
The formation of the ?lm or coating on’ the
55 surface of the article being coated may be ef
fected in a conventional manner. In order, how
ever, to achieve the preferred results of which‘
the present invention is capable using a relatively
thin coating, the dried coating is ?ashed at a
_ teners such as for instance petroleum jelly, may 60 temperature above the melting point of the waxy
be employed at similar concentrations. ,
protective agent. This apparently has the eifect
To‘improve the’ properties of the ?lms still
of bringing the wax to the surface to form a
further, a plasticizer for the resin may be em
“bloom” which acts to prevent penetration by
ployedin conjunction with the softener. This
plasticizer must be non-toxic and capable of act 65
The thickness of the ?lms formed may vary
ing to plasticize the resin at a concentration in
considerably. Satisfactory moisture-proof ?lms
for commercial purposes are in the neighborhood
su?icient to contaminate the coating with odour
or taste-giving properties. Suitable plasticizers ' of 1 mil in thickness.
of this type are butyl phthalyl butyl glycolate
The?lms may also be modi?ed by treatment
and methyl phthalyl ethyl glycolate. The plas 70 with the pigments or fillers usually employed
with’ polyvinyl acetate resins. Food products and
ticizers are preferably used at concentrations of
between about 3% and about 5% by weightofj
the total charge. When the coating is/?a'shed
according ,to the present invention‘: the wax
bloom has the effect of isolating the contents
other articles can be coated directly with ?lms as
opposed to coating a-container. Self-sustaining
,?lills can also be formed and rendered water
’ proof by the present teachings.
V _7
limitations shall be placed, th'ereon as may, be
required by the state of the prior art.v
These coatings have a widevariety or uses.
, l A principal utility lies in rendering water-perme
able materials waterproof. This is of particular
advantage'for the manufacture of cardboard con
tainers for aqueous materials; particularly foods
and beverages, such as milk, honey, fruit juices,
We claim:
uses will also be apparent to those skilled in
i the art.
, y
l. A process of preparing a coating composi
1 etc. Other materials may also be coated such as
\leather, fabrics, cellulosic materials such as for
‘instance. paper of various types. Many other
tion comprising adding a wax to an aqueous dis
persion of polyvinyl acetate produced by emul
sion polymerization. in the presence of an emulsi
fying agent effective to stabilize said dispersion,
said polyvinyl acetate beingpresent in an amount
ranging from about 30 to about 70% of the said
dispersion, said 'wax being present in an amount rangingfroxn about 12 to about 40% of the total
composition,’ the wax being added when the dis
persion has a temperature above the melting
3coating” is intended to indicate a coating able
point of the wax, then cooling the dispersion
jto withstand ‘water effectively for the purposes 15 slowly with stirring to about room temperature
to which the coated material is to be put. For
during a period of about 40 minutes to 2 hours
instance, containers for aqueous liquids must'be
whereby the ,wax constitutes a ph'ase of said dis
su?iciently water-proof that‘ the container‘ will,
persion in small discrete particles.
‘under the conditions of manufacture, handling
2. A process accordingto claim 1 wherein the V
In this speci?cation, the term "waterproof
and use, stand up to the satisfaction of the trade 2o wax is a para?in wax having a melting point
1 and of consumers. within a range from about 47° F. to about 14=0f7 F.
It will be understood that, without departing
' 3. A process according to, claim 1 wherein
‘from 'the-spirit'of the invention or the scope of
there 'is added to the dispersion an oleaginous
softener for the wax and a plasticizer for-the
fthe claims, various modi?cations may be made
‘inqthe speci?c expedients described. Thelatter
‘are illustrative only and not offered in a re
stricting sense, it being desired that only 'such
25 polyvinyl acetate.
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