Note: Descriptions are shown in the official language in which they were submitted.
3~
12161
:
~',
~ BACKG~OUND OF_T~E INVENTION
::
Coatings play a useful role in the manufac-
ture of a great many articlecs which ind wide use in
nearly all facets of contemporary life. Until recently,
nearly all coatings were applied with the employment of
a hydrocarbon based solvent which evaporated leaving a
dried coating on the article which was to be coated. '~
This system met with increasing disfavor as the price
of organic solvent increased and as the deleterious
;~ environmental effects of the evaporated solvent became
better understood. Systems aimed at solvent recovery to
reduce pollution and conserve solvent have generally
, ,, ~
10 proven to be expensive and energy intensive. In
response, those skilled in the art ha~e devised a class
. ,~
of coatings termed radiation-curable coatings in which,
upon exposure to radiation, virtually all of the liquid
portion of the coating is converted to cured coating re- ;
sulting in little solvent emission. ~-
Unfortunately many of the radiation-curable
coatings which have been here~ofore manufactured are
highly viscous and difficult to apply to the substrate
requiring dilution of the coating material with volatile
. "
~ 20 solvents. A radiation-curable coating which is of such
i~ low viscosity so as to avoid the use of diluents would be
~` of great advantage.
~` '
.
~L~34~31~
... . .
..,
' 12161
SUMMARY OF THE INVENTION
~: It has now b~en found that compositions formed
. .
from the reaction of a silicone carbinol, a polyisocyanate
and a hydroxy-functional acrylate can be incorporated in
radiation-curable coatings and that the resulting coa~ings
. are significantly less viscous than the heretofore avail-
;f~ able coatings.
.,
~ DESCRIPTION OF_THE INV~NTION
;,~ ~,
~, .;, ~ .
:~,. The acrylated urethane silicone compositions
of this invention are the reaction products of a
; 10 silicone havin~ at least one reactive hydroxyl group in
the molecule (a silicone carbinol~, an organic poly-
isocyanate and a hydroxyalkyl acrylyl compound; all as
hereinafter defined.
.i The silicone carbinols useful are those having
,; : a plurality of hydroxyl groups in the molecule, and many
,~ .,
,~ are commercially available. Among those suitable ase
those represented by the formula R(OH)n in which R represents
a polysiloxane moiety and n is an integer having a value
`~ of ~rom 2 to about 4. Basically two structures are
known, the simple polydimethylsiloxy type and the grafted
,i"i.~ 20 copoly type.
The polydimethylsiloxy type can be represented
by the foImula
:
: 3 :
~L3~38~
12161
CH3 CH3 ~ CH3
l I ,,
HOR' - SiO SiO - - - SiR'OH
CH3 CH3 _ x C 3
and the copoly type o~ the formula
(C~3)35iO t 5~ o ~ Si(C~3)3
(O CnH2n)yO
- .
wherein R' is an alkylene group having from l to 16 . ::
carbon atoms; n is an integer having a value of 2 or
3; x has a value of:from 1 to 1000, y has a value of
from O to 15; and 2 has a value of from 1 to 6. ~.
;: The organic polyisocyanates are known com-
: pounds and can be represented by tha general formula
Q(NCO)m wherein m has a value of from 2 to 5 and Q is
: ; the residual organic portio.n of the molecule to which
: the isocyanato groups are attached. Among those suitable
for use~in~this invention one can mention 3,5,5-~rim- :~
ethyl-l~isocyanato-3-isocyanato-methylcyclo~exana, di(2-
isocyanatoethyl)'bicyclo [2,2,1]-hept-5-ene-2,3-di~
carboxyIate, 2,4-tolylene diisocyanate, 2,6-tolylene ~ -
:
~3~
12161
diisocyanate, 4,4'-diphenyl- ~
methane diisocyanate, dianisdine diisocyanate, tolidine
diisocyanate, hexamethylene diisocyanate, ~he m- and p-
xylylene diisocyanates, tetra~et:hylene diisocyanate, di-
cyclohexyl-4,4'-methane diisocyanate, cyclohexane-l,
4-diisocyanate, l,S-naphthylene diisocyanate,4,4'
diisocyanate diphenyl ether, 2,4,6-triisocyanate toluene,
4,4',4"-triisocyanate triphenyl methane, diphenylene-4,4-
diisocyanate, the polymethylene poly-phenylisocyanates,
as well as any of the other organic isocyanates known to
the average skilled chemist.
The hydroxyalkyl acrylyl compounds suitable for
use in producing the acrylated urethane silicones are
those of the formula
CH2 = CCOOR"OH
wherein X is hydrogen or methyl and R'l is a linear or
branched divalent alkylene having from 2 to about 5 carbon
atoms. Illustrative thereof one can mention hydroxyethyl
acryla~e, hydroxypropyl acrylate, hydroxypentyl acrylate
and the corresponding methacrylates.
A si.mple representative formula for the acry-
lated urethane silicones produced using an organic -
diisocyanate and a silicone carbinol having two hydroxyl
groups is the following: i
1 ' '
(CH2=CHCOOR"OOCNHQ~HCOO)2R ~ '~
- :;
-5- ;
,
;, . . . ~ , . . .. .. . . .. ... . . .. . . ..
- ~3~
- ,,
12161
in which X, R and R" have the meanings previously in- ~~
dicated and Q is the polyvalenl: residue remaining after
reaction of polyisocyanate and can be linear or branched
alkylene having from 1 to 10 carbon atoms; arylene,
alkarylene or aralkylene having from 6 to 12 carbon atoms;
cycloalkylene having from 5 to 10 carbon atoms, or bi-
cycloalkylene having from 7 to 15 carbon atoms. Those
skilled in the art can readily write the formulas for
the products prepared using polyisocyanates and carbinols
of other functionalities.
In producing the acrylated urethane silicones
one initially produces a pr~polymer containing free
; isocyanato groups and then reacts the free isocyanato
groups with a reactant containing a reactive hydrogen atom.
Thusj in one embodiment of the reaction, the silicone
carbinol is reacted with a sufficient excess of organic
polyisocyanate to permit reaction of all of the hydroxyl
groups with isocyanato groups but still have unreacted at -
least one free isocYanato equivalent per mole of pre-
polymer produced,~ thereby producing an isocyanato terminated
prepolymer. Thereafter this prepolymer is reacted with
the hydroxyalkyl acrylyl compound. In a second embodiment ~ ~
of the reaction the prepolymer is produced by initially -
reacting the organic polyisocyanate with the hydroxyalkyl
~ acrylyl compound and then reacting the prepolymer with
; the silicone carbinol.
~ In either mode of operation the reaction of
.
~ the silicone carbinol, polyisocyanate and acrylate to form
: :~
6-
- ~ ~ 3 ~ ~ 4
12161
the compositions of this invention can be carried out
at a temperature of from OC to 125C. The preferred
temperature is ambient.
The reaction can be carried out at subatmospheric,
atmospheric or superatmospheric pressure; the preferred
pressure is atmospheric.
The reaction time will vary according to the
size of the batch, the temperature and pressure and the
nature of the particular silicone carbinol, polyisocyanate
and hydroxy-functional acrylate reactants being employed.
The reaction will proceed uncatalyzed, but a
catalyst can be employed to expedite it. Such catalysts
are well known in the art and include dibutyl tin dilaurate,
stannous octoate, dioctyl tin diacetate, morpholine,
triethylene diamine as well as any other suitable urethane
cataLyst recognized in the art. The catalyst, if present,
~ can be in a concentration of from 0.01 to 1.0 weight per-
; - cent, preferably from 0.05 to 0.2 weight percent, based
on the total weight of the reaction mixture.
The acrylated urethane siLicone compositions
of this invention can be used as coating compositions
either alone or in mixture with other reactive monomers,
solvents, pigments, fillers and other a~ditives. The ~ ;
coating compositions can be applied by con~entional means
and cured by exposure to ultraviole~ light or to high
energy radiation such as gamma-ray, alpha-particle, beta-
particle and accelerated electrons or by heat. If
ultraviolet Light is employed the coating composition ~-
-7-
,
. . . ~ . ,. . . , . ., . ,. . . .. . ~ : .. . . . . . . .
L?~
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preferably contains a photoinitiator. Illustrative of
such photoinitiators one can namer~ di-S-butoxyaceto-
phenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenyl-
acetophenone, benzophenone, p-methoxybenzophenone, aceto-
phenone, m-chloroacetophenone, propiophenone, xanthone,
benzion, benzil, benzaldehyde, naphthoquinone, anthra-
quinone and the like. The photoinitiator may be used
singly or in mixtures and is present in a concentration o
from 0 to 10 weight percent preferably rom 0.5 to 5 weight
percent based on the weight of the acrylated urethane
silicone present.
When heat curing is employed there can be employed
free radical initiators in a concentration of from about
0.1 to 10 weight percent, preferably from 0.5 to 5 weigh~
percent based on the weight of the acrylated urethane
silicone present. Illustrative of such free radical
initiators one can name di-t -butyl peroxide, dicumyl
peroxide, t-butyl hydroperoxide, t-butyl peracetate, per-
acetic acid, perbenzoic acid, benzoyl peroxide, dichloro-
benzoyl peroxide, azobis(isobutyrontrile), dimethylazobis(isobutyrate) and the like.
The coatings can be applied to any acceptable
substrate such as wood, metal, glass, abric, paper,
fiber, plastic: that is in any form, e.g. sheet, coil, molded, -
film, panel, tube, etc., by conventional means including
spray curtain~ di~ pad~ roll-coating and brushing procedures.
In a typical embodiment isophorone diisocyanate
,
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and dibutyl tin dilaurate as catalyst are charged to a
flask, stirred and heated, whil.e a silicone carbinol is
added dropwise. After completi.on of this reaction,
2-hydroxyethyl acrylate is added dropwise and the mixture
is stirred and heated ~or an additional period to complete
the reaction. The acrylated urethane silicone produced
is stabilized with hydroquinone monomethyl ether. A
coating is produced by blending with 2-(N-methyl-carbamoyl)
oxyethyl acrylate and.~,~ -di-S-buto~yacetophenone as
photoinitiator. When applied to release paper and irradi-
ated with ultraviolet light, the liquid cured to a polymerized
film.
It was completely unexpected and unobvious
to find that the reaction of a silicone carbinol, a poly-
isocyanate and a hydroxy-functional acrylate would produce
; an acrylated urethane silicone which has a low viscosity :-
so that it can be easily coated on substrates without the ~ ;
the use of diluents, and which can be employed in a
radiation-cu~able composition. ~:
The acrylated urethane silicones are
especially useful in the form~lation of low viscosity
varnishes for application over conventional ink prints
whLle the ink is still in the uncured state, with sub- -
sequent curing of the varnish by exposure to radiation. -;
The unique properties of the acrylates urethane silicones
such as a low viscosity/molecular weight ratio good flow-
: ~ ',- ,
_g_ ~
:
3 ~
12161
out performance, good wetting of the ink surface combined
with minimal miscibility with t:he ink make them particularly
good choices ~or this application in view of the fact that
the commonly used organic acrylate materials, when used
in thls application yield varnishes which do not provide
the desired high level of gloss combined with good film
properties, such as scratch resistance, flexibility and
adhesion, a~ter the ink has cured to a solid state by the
process of vehicle penetration into the substrate and
oxidation of the contained drying oils.
The following examples serve to further
illustrate the invention.
Example 1
There were charged to a 500 ml four-neck round-
bottom flask, equipped with a mechanical stirrer, hea~ing
mantle, air condenser, dropping funnel, thermometer and
: dry nitrogen purge, 37 grams of isophorone diisocyanate ;
and 0.4 gram dibutyl tin dilaurate as catalyst. The mi~
;~ ture was heated with stirring to 40C and kept at the
~ 20 temperature while 200 grams of silicone polycarbinol was
:: stirred in dropwise. The polycarbinol had the general
formula ~ :
Me Me Me
l l
HOR- Si- O - Si o - - Si - ROH
1, I
Me Me Me
-10-
,: , ~ ..... . . . .
~ ~ 3 ~
12161
It had an average hydroxyl equivalent weight of 1200 and
a viscosity of 320 centistokes at 25C. T~hen the addition
was completed, the mixture was stirred for another 15
minutes to complete reaction and formation of the isocyanato
terminated prepolymer, after which 21 grams of 2-hydroxy-
ethyl acrylate was added dropwise while the mixture was kept
at 40C and stirred. After the addition of the acrylate
the resulting mixture was stirred for 4 hours while the
temperatures was kept between 40C to 50C. Titration with
dibutylamine indicated that the free isocyanato content
was less than 0.1 weight percent. After this, 0.05 gram
of hydroquinone monomethyl ether was added to the acrylated
urethane produced as a stabili7er and was stirred for
fifteen minutes.
Seventy parts of the acrylated urethane silicone ~-
produced was formulated with 30 parts of 2-(N-methyl-
; carbamoyl)oxyethyl acrylate and 1 part ofz~ ,di-S-butoxy-
acetophone as photoinitiator. The formulation was coated
on release paper and irradiated by exposure for about 11.5 ;~
,~,
seconds, under a nitrogen atmosphere, to ultraviolet light
at a wavelength of about 3500 angstrom units. The liquid
formulation cured to a dry ~ilm and was removed from the ;~
release paper.
The film was placed in a constant temperature/
humidity chamber overnight. The next day a 0.25 inch wide
strip was cut and placed in a 1.0 inch gauge length cross-
head of a stress strain testing machine. The film strip was
3 ~
12161
stretched to breakage and the force at failure was used
together with the width and thickness to calculate the
force per unit area at failure. The ultimate elongation
was calculated using the formula
Ultimate Elongation % - ( L _ ~ 100
where L is the length at failure and Lo is the original
gauge length. The film was found to have a tensile
strength of 1200 psi and an ultimate elongation of 43 per-
cent.
Example 2
The coating formulation produced in Example
1 was coated on a steel panel and then irradiated under a
nitrogen atmosphere for about 1.9 seconds using ultra-
violet light at a wavelength of about 3500 angstrom units.
The liquid cured to a solid film. A piece of paper towel
was placed on the coating and saturated with acetone. The
time until the coating was attacked was measured. The
coating had a time rating of 153 seconds.
E ample 3
There were charged to the apparatus described
in Example 1 46.5 grams of bis(4-isocyanatocyclohexyl)
methane, 114. grams of 2-(N-methylcarbamoyl)oxyethyl
acrylate ancl 0.4 gram o~ dibutyl tin dilaurate as catalyst.
The mixture was heated and stirred as in Exa~ple 1 and
.
-12-
; , - . ~ . . . ~ .. .
3~
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205 grams of the silicone polycarbinol used in Example 1
was added dropwise to produce an isocyanato terminated
prepolymer. Fifteen minutes after the polycarbinol addition
was completed, 21 grams of 2-hydroxyethyl acrylate was
added dropwise followed by 0.05 gram of hydroquinone mono-
ethyl ether as polymerization inhibitor. The resulting
mixture was stirred for 5 hours while the temperature was
ke~t at rom 50C to 55C. Titration with dibutylamine
indicated that free isocyanato content was less than 0.1
weight percent. Thereafter 99 parts of this acrylated
urethane silicone was combined with 1 part of ~ ,o~-di- ~ ~
S-butoxyacetophenone as photoinitiator. The resulting ~ ~;
mixture was coated on release paper and irradiated for
about 1.9 seconds u~der a nitrogen atmosphere using ultra-
violet light at a wavelength of about 3500 angstrom units.
The liquld coating cured to a dry film. The film had a
tensile strength of 110 psi and an ultimate elongation of
43 percent.
. ,:
Example 4
There were charged to a 500 ml four-neck round-
bottom 1ask, equipped with a mechanical stirrer, cooling
. . .
water bath and dropping funnel, 11.1 grams of isophorone
diisocyanate and 5 drops of dibutyl tin dilaurate as ~
catalyst. While the temperature was maintained at about ~ ;
20C to 25C with the cooling water bath, 7 grams of
2-hydroxyethyl acrylate was added dropwise with stirring.
When the addition was complete the mixture was stirred at
,
-13-
3 ~
12161
room temperature for about 16 hours to complete formation
of the isocyanato terminated prepolymer. Thereafter 50
grams of silicone polycarbinol having a hydroxyl number of
200 mg.KOH/g, a specific gravity of 1.06 at 25C and a
viscosity of 350 centistokes at 25C was added dropwise
and the mixture was stirred at ambient temperature for
about 24 hours. The silicone polycarbinol had the chemical
formula
H3 l _1H3 ~
(CH3)3Sio - SiO l -SiO - _Si(CH3)3
H3 1 C3H6
(OC2H4)7,50H_ 5,5
~ ~,
'rhereafter 99 parts of this acrylated urethane silicone
was mixed with 1 part of ~, ~-di-S-butoxyacetophenone
as photoinitiator. The resulting mixture was coated on
release paper and then irradiated for 2.88 seconds under a
nitrogen atmosphere using ultraviolet radiation at a wavelength of about
3500 angstrom units. The liquid cured to a dry film; it
had a tensile strength of 64 psi and an ultimate elongation
of 19 percent.
Example 5
There were charged to the apparatus described
in Example 4 11,1 grams of isophorone diisocyanate and 5
drops of dibutyl tin dilaurate as catalyst. ~hile the
., .
-14-
.. .. .
3 ~
12161
temperature was maintained at 20C to 25C with the cooling -~
water bath 5.8 grams of 2-hydroxyethyl acrylate was added
dropwise with stirring. When the addition was complete
the mixture was stirred at room temperature for about 7 hours
to complete formation of the isocyanato terminated pre-
polymer. ThereaXter 50 grams of a silicone polycarbinol
having a chemical formula of
'~:
CIH3 ~ IH3 CH3
(CH3)3SiO - SiO - _ SiO _ _Ci~ ~ Si(CH3)
10C~3 - ~ l2H6 13~6
~oC~H4)7 5o~1 ~OC2H4)7.50H ¦
were added dropwise. A~ter the addition the mixture was
stirred at ambient temperature for about 15 hours and the
acrylated urethane silicone composition was recovered.
Thereafter 99 parts of the above-described mixture was
mixed with 1 part of ~ di-S -butoxyacetophenone as
photoinitiator. The resulting mixture was coated o~
rele~se paper and irradiated for 2.88seconds under a
nitrogen atmosphere using ultraviolet radiation at a wave-
length of about 3500 angstrom units. The liquid cured to
a dry film.
Example 6 ;
To 49;parts o~ the acrylated urethane silicone ~`
prepared in Example 4 there was added 1 part of
- 1 5 -
... .,.,.............................................................. :
~ ~3~
12161
~ , O~-di-S-butoxyacetophenone as photoinitiator, resulting
in a clear varnish having a viscosity at 25C of about
2000 cps. A sheet of coated offset paper was prepared by
coating an ink film using a hand proofer with a large
charge o black ink on its surface so as to obtain two com-
plete roller revolutions down the center of the sheet from
top to bottom then immediately applying the varnish over
the ink film with another hand proofer equipped with a 180
line/inch quadragra wre engraved metering roll. The printed -
and coated paper thus formed was then immediately passed
through an ultraviolet curing unit delivering a flux of
160 watts per square foot, under a nitrogen atmosphere,
over a path length of 2 feet. The conveyor belt speed was
set at 275 ft.lmin giving an exposure time of about 0.44
second. Cure of the varnish was ~udged to be complete by
virtue of its resistance of fingernail scratch. The -
properties of the varnish over the ink film were evaluated
20 hours after curing. Flow-out and wet~ing were judged
to be good using vi~ual comparative methods. Gloss level
measured by a 60C gloss meter was 72 percent.
Example7_
There were charged to the apparatus described
in Example 4~a.7 grams of an 80/20 mixture of 2,4-and 2,6-
isomers of toluene diisocyanate and 5 drops of dibutyl tin
dilaurate as catalyst. While the temperature was maintained
at about ambient with the cooling water bath, 7 grams of
2-hydroxyethyl acrylate was added dropwise with stirring.
When the additLon was complete the mixture was stirred at
-16-
12161
room temperature for about 3 hours to complete the formation
of the isocyanato terminated prepolymer. Thereafter 50
grams of the silicone poylcarbinol described in Example 5
was added dropwise. After this addition the mixture was
stirred at ambient temperature for about 16 hours to form
the acrylated urethane silicone composition; after which
0.01 gram of hydroquinone monomethyl ether was added as
polymerization inhibitor. Thereafter 73 parts of the ~;
acrylated urethane silicone was formulated with 25 parts
of the diacrylate derivative of the 4 mole ethoxylate of
2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxy-
propionate and 2 parts of ~ -di-S-butoxyacetophenone
as photoinitiator. This formulation was applied to coated
offset paper and cured using the procedure described in
Example 6. The resultant dry film was glossy and free of
surface tack.
Example 8
There were charged to the apparatus described
in Example 4, 35.5 grams of isophorone diisocyanate and 5;~
drops of dibutyl tin dilaurate as catalyst. While the
temperature was maintained at about ambient with the cooling
water bath, 20.0 grams of 2-hydroxyethyl acryIate was
added dropwise with stirring. When the addition was complete
the mixture was stirred at room temperature for about 4
hours to complete formation of the isocyanato terminated
prepoplymer. Thereafter 50 grams of silicone polycarbinol~ `
described in Example 4 was added dropwise. After thls
addition the mixture was stirred at ambient temperature
-17-
3 ~
12161
for about 16 hours to form the acrylated urethane silicone
composition. Thereafter 73 parts of this acrylated
urethane silicone was formulated wit~ 25 parts of
trimethylolpropane triacrylate and 2 parts of,~ "~-di-S-
butoxyacetophenone as photoinitiator. The formulation
had a viscosity of 1010 cps at 25C. The mixture was
appliçd as a varnish over uncured ink and cured following
the procedure described in Example 7 resulting in a tack-
free surface. After the varnish was cured, the sheet was
aged for about 20 hours and evaluated using the tests
used in Example 6. The results were as follows
60 gloss - 82% ~;
flow-out - fair to good
wetting - good
Example 9
There were charged to the apparatus described
in Example 4, 10.5 grams of a mixture of 2,2,4- and
2,4,4-isomers of trimethyl hexamethylene diisocyanate
and 5 drops o~ dibutyl tin dilaurate as catalyst. While
the temperature was maintained at about ambient with the
cooling water bath, 7 grams of 2-hydroxyethyl acrylate
was added dropwise with stirring. When the addition was
complete the mixture was stirred at room temperature for
about 4 hours to form the isocyanato terminated prepolymer.
Thereafter 50 grams of the silicone polycarbinol described
in Example 4 was added dropwise. After this addition
the mixture was stirred at ambient temperature for about
1~
~13~L9~4
12161
16 hours to complete production of the acrylated urethane
silicone. Thereafter 73 parts of this acrylated urethane
silicone was for~ulated with 25 parts of pentaerythritol
acrylate and 2 parts of~vO~-di-S-butoxyacetophenone as
photoinitiator. The formulation had a viscosity of 2300
cps at 25C. It was then applied over uncured ink and
cured following the procedure described in Example 6 re-
sulting in a clear tack-free film. After the varnish
was cured, the sheet was aged for 20 hours and evaluated ~-
using the tests in Example 6. The results were as follows~
60 gloss - 76%
flow-out - fair '
wetting - good `~ ;~
"''~, ..
Example 11
Four varnishes were prepared using the pro-
cedure described in Example 6. For comparative purposes, ~-
two other ~arnishes, representing the heretofore state of
the art were produced and evaluated using the same pro- ~
cedures. The compositions of each varnish and the results~;
of the evaluation are shown in Table I. /~
' " .
' ,'
19- ' - ~
~34~8~
12161
TABLE I
Varnish (parts by weight)
A B C D E F
Acrylated Urethane
Silicone of Example 4 39 50 42 17 - -
Polyether Urethane
Oligomer - - - 12 2~ -
Caprolactone Polyol
Urethane Oligomer ~ 8
10 Adduct of 1 mole ~-
: Isophorone Diisocyanate
and 2 moles 2-hydroxy-
ethyl acrylate - - - 6 - 16 :~
,
Trimethylolpropane
triacrylate 61 - 53 60 66 44
Pheno~yethyl acrylate - - 5 5 5 12
,
-di-S-butoxyaceto-:
phenone 2 2 2 ~ 2 2 2
Compound A
20 Compound B - 50 - - - -
60 gloss 74 78 72 ~ 75 67 68
~ Flow-out Good Good Fair Good Fair Good
:~ : to to ::
Good Good ~ - -
Resistance to cracking .: .-
when folded Good Exc. Exc. Good Fair Fair
;. .-
,
,-
-20-
~ .
'.
~34~
,-. .
CH3 CH3 12161
Compound ~ - (CH3) 3Si4)S ~ OS (CH3)
C3H6 ~2H4)~3~I603~ (CH3)
Compound B - The diacrylate derivative of the 4 mole
ethoxylate of 2,2-dimethyl-3-hydroxypropyl-2,
2-dimethyl-3-hydroxypropionate
This example demonstrates the superior properties of
varnishes employing the acrylated urethane silicones of
this invention over those of the heretofore present state
o f the art.
', ,,
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