Note: Descriptions are shown in the official language in which they were submitted.
/ ~ "
The present invention relates to drag reducing coatings for surfaces
moving through water or surfaces against which water is flowing.
It is an object of the present invention to reduce the resistance
or drag developed on moving watercraft through water.
Another object is to develop novel anti-foulant compositions.
A further object is to provide watercraft and underwater static
structures with an improved anti-foulant coating.
Still further objects and the entire scope of applicability of the
present invention will become apparent from the detailed description given
hereinafter; it should be understood, however, that the detailed description
and specific examples, while indicating preferred embodiment of the invention,
are given by way of illustration only3 since various changes and modifications
within the spirit and scope of the invention will become apparent to those
skilled in the art from this detailed description.
It has been found that these objects can be obtained by using
coatings comprising film forming polymers which have the ability to absorb
water, but which are insoluble in water, and remain intact, swollen on the
surface thereby coated, as coatings at least for the underwater por~ion of ;'
watercraft and underwater static structures.
Accordingly the invention provides a marine structure which is a j;
watercraft having an adherent continuous exposed coating consisting essentially
of a water insoluble hydrophilic polymer which is swellable to an extent of .-
at least 10% in water wherein the hydrophilic polymer is selected from the
group consisting of hydrophilic cellulose esters, hydrophilic cellulose ethers,
hydrophilic polyurethanes, hydrophilic vinyl lower alkyl ethers, vinyl alcohol
group containing polymer, polyvinyl pyrrolidone, partially hydrolyzed poly~
acrylonitrile, ethylene-maleic anhydride copolymer, styren~-maleic anhydride
copolymer, proteins, high molecular weight polyalkylene oxides, and phenoxy
resins wherein the coating is sufficient to reduce the drag of the watercraf~
when in ~ater.
Many conventional water-soluble polymers are useful in the practice ,~
of this invention3 if, after application to the surface they are crosslinked
to render them insoluble. The optimum amount of water
absorption to obtain maximun drag -
,: ".
`"':
_ J~_
'~ ' '"''' ~ '
' .:
~ ', :.,
reducing effect varies somewhat with the composition of the
polymer, film thickness, etc., but in general the polymer
must absorb a minimum of about l~/o by weight of water to be
effective. Preferably, it should absorb 20% of water to
12~/~, and it can absorb even more, e.g. 500% or 2/00~/o by
weight.
The term marine coating is used in the present ap-
plication and claims to cover both coatings for watercraft
and underwater static structures~ The term watercraft in-
cludes movable boats of all kinds, including, but not limit-
ed to sailboats, yachts, inboard and outboard motor boats,
rowboats, tor launches, canoes, Kayaks, water skis, surf-
boards, ocean liners, tugboats, tankers and other cargo
ships, submarines, both of the atomic and conventional vari-
eties, aircraft carriers, destroyers, etc. Underwater stat-
ic structures include, but are not limited to wharves, piers, -
permanently moored watercraft, pilings, bridge substructures, ` ;
underwater oil well structures, etc. The underwater surface
can be made of wood, metal, plastic, fiberglass, concrete or
other material.
. .
The anti-foulant compositions are useful as marine -
coatings to render the structure (moving or static) resis-
tant to fouling by marine organisms such as barn`acles, algae, `
slime, acorn-shells (Balanidae~ goose mussels ~Lepadoids),
tube-worms, sea moss, oysters, brozoans, tunicates, etc~
It is critical that the hydrophilic polymer, e~g,
acrylic resin, be water insoluble, or rendered water insol-
uble, since otherwise it will not be permanently affixed to
the underwater surface.
The coatings of the invention effectively reduce
the "drag" or resistance developed on moving the coated sur-
face through water.
--2-- ^~
If it is desired to employ the coating solely to
effect friction reduction on racing or pleasure craft, for
example, which do not remain static in water for extended
periods, it is not necessary to incorporate an antifouling
agent.
-While not being bound by any theory it is believed
that the mechanism of friction reduction is two-fold. The
coating absorbs a substantial percentage of water and the `
water swollen coating exhibits a low contact angle with the
water n In addition, the swollen coatings are soft, (partic-
ularly if a linear polymer is employed) and th~ softness can !,~'. '
provide a hydrodynamic dampin~ effect and reduct turbulence
of the flow.
As stated in our Canadian Patent Applica~ion No.076,719
15 filed March 6,1970, preferably the hydrophilic monomer employed ;
is a hydroxy lower alkyl acrylate or methacrylate or hydroxy
lower alkoxy lower alkyl acrylate or methacrylate, e.g. 2-
hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, diethy-
lene glycol monoacrylate, diethylene glycol monomethacrylate,
20 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3- ` -
hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, dipro-
pylene glycol monomethacrylate and dipropylene glycol mono-
acrylate~ The most preferred monomers are the hydroxyalkyl
acrylates and methacrylates, particularly 2-hydroxyethyl ~-
25 methacrylate.
There can also be employed polymers of acrylate,
methacrylamide, n-alkyl substituted acrylamide and meth-
acrylamide such as ~-propylacrylamide, ~-isopropyl acryla-
mide, ~-isopropyl methacrylamide, ~-propyl methacrylamide,
30 ~-butyl acrylamide, N-methyl acrylamide and ~-methyl meth-
acrylamide, diacetone acrylamide, I~-(2-hydroxyethyl) acryl- ,
B :
. .. . i . ; .
. . , . ... ; . ~ .
~ . - ~\
~J~
amide and ~-(2-hydroxyethyl) methacrylamide.
Likewise, there can be employed copolymers of
these monomers with each other or with other copolymeriz-
able monomers. In fact, if the hydrophilic monomer gives
a product which is water soluble, e.g. polyacrylamide, it
is necessary to employ a copolymerizable monomer to render
it only water swè~l~ble, rather than water solubleO The co-
polymerizable monomer can be used in an amount of 0~05 to
50%. Preferably, comonomers include methyl acrylate, ethyl
acrylate, isopr~pyl acrylate, propyl acrylate, butyl acry-
late, sec. butyl acrylate, pentyl acrylate, 2-ethylhexyl ;:
acrylate, methyl methacrylate, ethyl methacrylate, propyl
methacrylate, isopropyl methacrylate, butyl methacrylate,
sec. butyl methacrylate, pentyl methacrylate, lower alkoxy-
ethyl acrylates and methacrylates, e.g. methoxyethyl acry-
late, methoxyethyl methacrylate, ethoxyethyl acrylate and `~
ethoxyethyl methacrylate, triethylene glycol acrylate, tri-
ethylene glycol methacrylate, glycerol monoacrylate and
glycerol monomethacrylate. ;
Thère can also be used unsaturated amines8 P-
aminostyrene, o-aminostyrene, 2-amino-4-vinyltolueneJ alkyl-
amino alkyl acrylates and methacrylates, e.g. diethylamino-
ethyl acrylate, diethylaminoethyl methacrylatet dimethyl-
aminoethyl acrylate, dimethylaminoethyl methacrylate~ t-
butylaminoeth~l acrylate, t-butylaminoethyl methacrylate~
piperidinoethyl acrylate, piperidinoethyl methacrylate, mor-
pholinoethyl acrylate, morpholinoethyl methacrylate, 2-
vinylpyridine, 3-vinyl pyridine, 4-vinyl pyridine, 2-ethyl-
5-vinyl-pyridine, dimethylamino propyl acrylate, dimethyl-
amino propyl methacrylate, dipropylaminoethyl acrylate, di- ;~
propylaminoethyl methacrylate, di-n-butylaminoethyl acrylate,
-4-
.
.. ~ . ... , . . . . . . . .
di-n-butyl aminoethyl methacrylate, di-sec. butylaminoethyl
acrylate, di-sec. butylaminoethyl methacrylate, dimethyl-
aminoethyl vinyl ether, diethylaminoethyl vinyl sulfide,
diethylaminoethyl vinyl ether, aminoethyl vinyl ether,
aminoethyl vinyl sulfide, monomethylaminoethyl vinyl sulfide,
monomethylaminoethyl vinyl ether, N-(gamma-monomethylamino)
propyl acrylamide, ~-(beta-monomethylamino) ethyl acrylamide, ; -
N-(beta-monomethylamino) ethyl methacrylamide, 10-aminodecyl
vinyl ether, 8-aminooctyl vinyl ether, 5-aminopentyl vinyl
ether, 3-aminopropyl vinyl ether, 4-aminobutyl vinyl ether,
2-aminobutyl vinyl ether, monoethylaminoethyl methacrylate,
~-(3,5,5-trimethylhexyl) aminoethyl vinyl ether, N-cyclohex-
ylaminoethyl vinyl ether, 2-(1,1,3,3-tetramethylbutylamino)
ethyl methacrylate, N-t-butylamino-ethyl vinyl ether, ~-
methalimina-ethyl vinyl ether, N-2-ethylhexylamlnoethyl
vinyl ether, N-t-butylaminoethyl vinyl ether, N-t-octyl-
aminoethyl vinyl ether, 2-pyrrolidinoethyl acrylate, 2-pyr-
rolidinoethyl methacrylate, 3-(dimethylaminoethyl)-2-hydroxy-
propyl acrylate, 3-(dimethylaminoethyl) 2-hydroxypropyl
methacrylate, 2-aminoethyl acrylate, 2-aminoethyl methacry-
late. The presently preferred amino compounds are alkyl-
aminoethyl acrylates and methacrylates, most preferably, t-
butyl- aminoethyl methacrylate.
While linear polymers (including both homo and co-
polymers) are preferred when the hydrophilic resins are used
only to reduce the resistance on moving a coated watercraft
surface through water there can also be employed cross-
linked hydrophilic copolymers. Such cross-linked copolymers
are frequently advantageously employed when antifouling agents
are included in the composition to insure more permanent ad-
herence to the underwater strUcture.
--5--
Preferably, the cross-linking agent is present in
an amount of 0.1 to 2.5%, most preferably, not over 2.0~/
although ~rom 0.05 to 15%, or even 20~/c, of cross-linking
agents can be used. Of course, care should be taken that
cross-linking agents are not used in an amount which renders
the product incapable of absorbing at least 2~/o Of water.
Typical examples of cross-linking agents include
ethylene glycol diacrylate, ethylene glycol dimethacrylate, 7 .'
1,2-butylene dimethacrylate, 1,3-butylene dimethacrylate,
1,4-butylene dimethacrylate, propylene glycol diacrylate,
propylene glycol dimethacrylate, diethylene glycol dimeth-
acrylate, dipropylene glycol dimethacrylate, diethylene gly-
col diacrylate, dipropylene glycol diacrylate, divinyl ben-
zene, divinyl toluene, diallyl tartrate, allyl pyruvate,
allyl maleate, divinyl tartrate, triallyl melamine, N,N'-
methylene bis acrylamide, glycerine trimethacrylate, di- -
allyl maleate, divinyl ether, diallyl monoethylene glycol -
citrate, ethylene glycol vinyl allyl citrate, allyl vinyl `-
maleate, diallyl itaconate, ethylene glycol diester of ita-
conic acid, divinyl sulfone, hexahydro-1,3,5-triacryltria-
zine, triallyl phosphite, diallyl ester of benzene phosphonic
acid, polyester of maleic anhydride with triethylene glycol,
polyallyl glucose, e.g. triallyl glucose, polyallyl sucrose,
e.g. pentaallyl sucrose, sucrose diacrylate, glucose dimetha-
crylate, pentaerythritol tetraacrylate, sorbitol, dimetha-
crylate, diallyl aconitate, divinyl citraconate diallyl
fumarate.
There can be included ethylenically unsat~rated
acids or salts thereof such as acrylic acid, cinnamic acid,
carotonic acid, methacrylic acid, itaconic acid,aconitic
acid, maleic acid, fumaric acid, mesaconic acid and citra-
,' :
--6--
' """'''"
conic acid. Also, as previously indicated there can be used
partial esters such as mono 2-hydroxypropyl itaconate, mono
2-hydroxyethyl itaconate, mono 2-hydroxyethyl citraconate,
mono 2-hydroxypropyl aconitate, mono 2-hydroxyethyl maleate,
mono 2-hydroxypropyl fumarate, monomethyl itaconate, mono-
ethyl itaconate, mono Me~hyl Cellosolve* ester of itaconic
acid (Methyl Cellosolve* is the monomethyl ether of diethy-
lene glycol), Mono Methyl Cellosolve* ester of Maleic acid. -`
The polymers can be prepared for use as casting
syrups, as aqueous dispersions, by aqueous suspension poly-
merization or as solutions in organic solvents such as ethyl
alcohol, methyl alcohol, propyl alcohol, isopropyl alcohol, -~
formamide, dimethyl sulfoxide or other appropriate solvent.
It has now been found that in addition to the
polymers set forth in our Canadian Patent Application No.
076,719, there can also be used as polymers in the prac-
tice of this invention polyvinyl alcohol, polyvinyl-N-pyrrol-
idone, copolymers of vinyl pyrrolidone with other monomers,
e.g. methyl methacrylate, cellulose ethers such as methyl ;
cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
partially hydrolyzed cellulose esters such as cellulose
acetate having a degree of substitution of 1~ 3 to 2.3, cel- ~"
lulose acetate-propionate and cellulose acetate-butyrate of
similar degree of substitution, carboxyl methyl cellulose,
etc., vinyl acetate-vinyl alcohol copolymers, e.g. (20:80) `
polymethylvinyl ether, polyethylvinyl ether, polyurethanes
formed by reaction of polyhydric alcohols such as glycerol,
sorbitol, mannitol, pentaerythritol, trimethylolpropane,
hexane 1,2,6-triol, mono or polysaccharides such as glucose, `~
sucrose, fructose and dextrin, tris dipropylene glycol phos-
phonate, tris dipropylene glycol phosphate with an amount
*trademark for 2-ethoxyethanol
- 7 -
- ~ .
,. ,
.. ; -
:
of diisocyanate insufficient to react with all the hydroxyl
functionality.
Such polyurethanes can have hydroxyl numbers of
100 to 500 and can be made from toluene diisocyanate, 4,4'-
methylene bis (phenylisocyanate), oxydi (phenylisocyanate),
4-methoxy-1,3-phenylene diisocyanate or any other convention-
al diisocyanate or higher polyisocyanates such as those men-
tioned in U.S. patent 3,127,373. ~here can also be used
polyurethanas formed by reaction of hydroxyl terminated
polyesters with such polyisocyanates providing the hydroxyl ;
groups are in excess. Examples of such polyesters are poly-
ethylene sebacates, the reduction product of an excess of ~ ~
l,4-butanediol with adipic acid and a small amount of tri- ~ ~-
methylolpropane of molecular weight 3,000 to 12,000, ethy-
lene glycol-propylene glycol adipate molecular weight l,900,
glyceryl adipate-phthalate. Likewise there can be used poly-
urethanes made by reacting such polylsocyanates with hydrox-
yl terminated polyethers, e.g. diethylene glycol, triethylene
glycol, dipropylene glycol, polyethylene glycol molecular
weights of 200 to 3,000, polypropylene glycol molecular
weight of 200 to 3,000, tetramethylene glycol molecular
weight 200, l,000 or 4,000, glycerol-propylene oxide adducts ;
of molecular weight 265, 1,000 or 3,000, hexane 1,2,6-triol-
propylene oxide adducts of molecular 500 to 4,000, oxypro-
pylated sucrose. The hydroxyl numbers of such polyurethanes
should be as indicated above.
Other suitable hydrophilic polymers include protein-
aceous polymers such as casein and gelatin~ high molecular
weight polyethylene oxide or polypropylene oxide, e.g. mol-
ecular weight of 3,000 or above, preferably at least 5,000,polyethylene i~ine, and water soluble polyelectrolytes such
: , :
-8-
, ,-
as polyitaconic acid, polyacrylic acid, vinyl ether-maleic
anhydride copolymers, e.g. where the vinyl ether is vinyl
ethyl ether, vinyl methyl ether or vinyl butyl ether, ethy- -
lene-maleic anhydride copolymers, styrene-maleic anhydride
5 copolymers (preferably containing at least 3~/a maleic an-
hydride units), methyl methacrylate-maleic anhydride copoly-
mers hydrolyzed ethylene-vinyl acetate copolymer containing
at least 3~h vinyl alcohol units, phenoxy resins, e.g. the
phenoxy resin of molecular weight 30~000~ see U.S. patent
10 3~305~526~ col. 9, line 60 et seq., polyvinyl acetals con-
taining free hydroxyl groups, e.g. polyvinyl formal-poly-
vinyl alcohol, polyvinyl butyral-polyvinyl alcohol.
Cross-linking of the applied coatings may be ac-
complished by a variety of techniques~ Curing of polymers
containing hydroxyl functionality may be done using ammoni-
um, potassium or sodium chromate or dichromate or other
strong oxidizing agents, e.g. in an amount 0.2 to 5% of the
solids, Titanates, e.g. tetraisopropyl titanate, tetrabutyl
titanate and tin compounds, e.g. stannous dodecanoate, stan-
nous octoate can be used in like amounts. Polymers contain-
ing other groups and vinyl unsaturation may be crosslinked
by incorporation of free radical generators such as organic
peroxides, e.g. any sodium peroxide, hydrogen peroxide, am-
monium or potassium persulfate, organic hydroperoxides, per-
acids, and peresters.
Examples of suitable per compounds include t-butyl
peroctoate, benzoyl peroxide, isopropyl percarbonate, 2,4-
dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cu-
mene hydroperoxidè and dicumyl peroxide.
The inciusion of agents to create redox systems
with the free radical generators aids in speeding the curing
,
,: .
action as is well known in the art.
It is critical, as stated, to render the hydrophil-
ic polymer water insoluble (if it is not already so) while `~
at the same time not destroying the hydrophilic prope~ties.
It is also critical that the hydrophilic polymer
form a continuous film outer coating on the watercraft or
other structurer i.e. it should not be masked or blocked by
a hydrophobic film former for example.
The hydrophilic polymer coatings of the present
invention can be coated over conventional antifoulants pro-
vlding there is sufficient permeability that the bottoms of
the watercraft are kept clean.
There also can be lncorporated with the hydrophil-
ic polymers in the coating compositions of the lnventlon to
provlde coatLngs to prevent fouling by marine organisms any
of the conventional inorganic or organic anti-foulants ln-
cluding cuprous oxide, copper powder, mercuric oxide, cup-
rous oxide-mercuric oxide, e.g. 3sl mercurous chloride,
organotin compounds including triphenyltin chloride, tri-
20 phenyltin bromide, tri p-cresyltin chloride, triethyltin `
chloride, tributyltin chlorlde, phènyl dlethyltin fluorlde,
tri (p-chlorophenyltin) chlorldé, tri (x-chlorophenyltin)
chloride, dibutyl ethyltin bromide, dibutyloctyltin bromide,
trlcyclohexyltln chloride, triethyltin stearate, tributyltln
. . , j, . . . ~.,,
25 stearate, trlethyltln fluorlde, tributyltin fluoride, di- ,
phenyl ethyltin chloride, diphenyl ethyltin fluorldé, tri-
phenyltin hydroxide, triphenyltin thiocyahate, triphenyltin
trichloroacetate, tributyltin acetate, tributyltin neodecan-
oate, trib~tyltin neopentanoate, trioctyltih neodecan~ate,
tributyltin oxide, trioctyltin oxide, triphenyltin fluoride,
tributyltin oleate, tripropyltin neodecanoate, tributyltin
.",
-10- ,'... .
laurate, tributyltin octanoate, tributyltin dimethyl carbo-
mate, tributyltin resinate, tributyltin chromate, amyldi-
ethyltin neodecanoate, tributyltin naphthanate, tributyltin
isooctylmercaptoacetate, bis (tributyltin) oxalate, bis
(tributyltin) malonate, bis (tributyltin) adipate, bis (tri-
butyltin) carbonate, organo lead compounds, e.g. triphenyl
lead acetate, triphenyl lead stearate, triphenyl lead neo-
decanoate, triphenyl lead oleate, triphenyl lead chloride,
triphenyl lead laurate, triethyl lead oleate, triethyl lead
acetate, triethyl lead stearate, trimethyl lead stearate,
triphenyl lead bromide, triphenyl lead fluoride, organic
compounds including 10,10'-oxy-bisphenoxazine (SA-546~, 1,
2 ~ 3-trichloro-4,6-dinitrobenzene, hexachlorophene, dichloro- -
diphenyl trichloroethane (DDT), phenol mercuric acetate,
tetrachloroisophthalonitrile, bis (n-propylsulfonyl) ethyl-
ene, etc. -
The antifoulant is releasably entrapped in the ~`
hydrophilic polymer coating. The quantity of antifouling
agent required in the coating, as would be expected, varies
20 with the particular agent used and the severity of fouling
tendency encGuntered in thè particular service to which the
coated vessel or static structure is to be used. In general,
the amount of antifouling agent when employed will range
from 2 to 20~/o of the resin by weight, although as littie as
0.1% of anti-foulant can be used based on the resin. The
amount of anti-foulant should be insufficient to prevent the
hydrophilic polymer from forming a continuous film~
Of course, there can be included in the formulation ~;~
conventional pigments and fih ers such as titanium dioxide,
red lead, bone black, red iron oxide, talc, aluminum sili-
cate, fullers earth, pumice, zinc oxide, calcium carbonate,
etc.
-~ tr~l~na~ -11-
,"~;""
The coatlngs of the present invention can be ap-
plled to the surfaces to be subjected to underwater condi-
tions from solution in organic solvents or from a~ueous dis-
persions. Suitable solvents include lower aliphatic alco-
hols such as methanol, ethanol, propanol and isopropanol or ;~
mixtures of these solvents with higher boiling alcohols
such as ethylene glycol, diethylene glycol, propylene glycol,
dipropylene glycol, ethylene glycol monomethyl ether, ethyl-
ene glycol monoethyl ether, diacetone alcohol, n-butanol,
10 sec. butanol, isobutanol and mixtures of these solvents with
water. In some cases aromatic and aliphatic hydrocarbons,
e.g. benzene, toluene, xylene and hexane can be used. ~- -
The coatings of the present invention generally
exhibit adequate adhesion to marine surfaces protected by
15 corrosion resistant Einishes such as epoxy or vinyl based
paints, to previously applied antifouling finishes and to
polyester-fiberglass laminates. Typical of such finishes
are those shown in Sparmann U.S. patent 2,970,923, Scott
U.S. patent 3,214,279 and Robins U.S. patent 3,236,793. ;
The thickness of the coating applied will vary ;
with the particular formulation emplo~ed and the method of ;~
application. It can be from 0.1 mil. to 250 mils. or more
in thickness. Usually it will be between 0.3 mil. and 5 a
mils. The co atings can be applied to the marine surface,
25 e.g. boat bottom or hull or wharf piling by any conventional
procedure such as brushing, dipping, spraying, roller coating,
etc.
Coating applied at boat yards, marinas or similar
locations will normally be placed in water soon after dry-
30 ing. These coatings if made from linear, alcohol soluble
polymers will remain alcohol soluble. However, as pointed
.:
-12-
,',',", , '~
'.
out supra it is also possible to provide cured or cross-
linked coatings which exhibit improved mechanical durabil-
ity. There can be used the peroxide catalysts referred to
supra alone, or as part of a 2-component catalyst system
which is mix~d into the coating solution immediately prior
to application~ Alternatively, the coating can be cured by
incorporating a free radical initiator and heating the coat-
ed surface aftér drying.
Two component catalyst systems for effecting cure
at ambient conditions, e.g. 20 C., include peroxides of the
type referred to upra together with such amine accelerators
as ~,~-dimethy~aminoethyl acetate, N,N-dimethyl aniline, N,
~-dimethyl aminoethanol, N,~-dimethyl toluidine. The accel-
erator can be used in an amount of 0.05 to 1 part per part
of peroxide, e.g. a mixture of 8~/o benzoyl peroxide and 11%
dimethylaniline can be employed. ~
Tha invention will be understood best in connec- `
tion with the drawings wherein:
FIGURE 1 shows a boat having a coating accordlng
to the invention, and
FIGURE 2 is a sectional view along the line 2-2 ~-
of Figure 1.
Referring more specifically to the drawingb, the
boat 2 in water 4 has a coating 6 of hydroxyethyl methacryl-
ate polymer (or hydroxypropyl cellulose) below the waterIine8. If desired, the entire boat can be coated with the poly-
mer. The thickness of the coating 6 is greatly exaggerated
for illustrative purposes.
EXAMPLE 1
-~
30 2-hydroxyethyl methacrylate (50 parts) and TiO
D (30 parts) are ground in a pebble mill to a fine powderO
-13-
-. :,
' ~ ' ~ ; . ~ ................... .
Additional 2-hydroxyethyl methacrylate (50
parts) is added along with ethylene glycol dimethylacrylate
(0.2 part~, cobalt naphthenate, a conventional metallic
paint dryer or catalyst ~0.1 part) and t-butyl peroctoate
(0.4 part). The resulting viscous syrup is painted onto a
wooden boat hull and cured at 20 to 35 C. The resulting
protective marine coating is characterized by its ability `
to discourage barnacle and algae growth and corrosion on
prolonged underwater exposure. Additionally it reduces the -
10 drag on moving the coated hull through water. ;
EXAMPLE 2 ,~
The procedure of Example 1 is repeated with the
modification that the coating syrup is cast onto a steel
hull and cured at 100 C. in the absence of cobalt naphthen-
15 ate. The drag on moving the coated hull through water was ~
reduced compared to an uncoated hull. ~ -
EXAMPLE 3
The procedure of Example 1 is repeated employing
an isomeric mixture of hydroxy isopropyl methacrylate isomer0 in place of the hydroxyethyl methacrylate.
EXAMPLE 4
To a glass-lined reactor was charged 800 lbs. of
ethanol, 200 lbs. of hydroxyethy~ methacrylate and 0.5 lb.
of t-butyl peroctoate. The reactor was flushed with nitroJ ~;
gen and heated to 80 C, over a period of 1 hour. The re-
actor was stirred at 80 C. for 7 hours, wherein 9~h conver-
sion of hydroxyethyl methacrylate to polymer was attained. ;
The resulting solution, containing 1~/~ polymer by
weight was used for the formulation of coatings for sailboats
and motorboats below the water line. The boats were made of `
wood, metal and fi~erglass (i.e. polyester impregnated fiber-
glass). -
EXAMPLE 5
Example 4 was repeated using 20 lbs. of methyl
methacrylate and 180 lbs. of hydroxyethyl methacrylate as
the monomer charge. A conversion of 95% was attained in 7
-14-
.'' ~',
, .
hours. The resulting solution was used for the formulation
of marine coatings in a similar fashion to example 4.
EXA~IPLE 6
Example 4 was repeated using 80 lbs. of methyl
methacrylate and 120 lbs. of hydroxyethyl methacrylate as
the monomer charge. A conversion of 90~/~ was attained in 6 '~ ;
hours. The resulting solution was used for the formulation
of marine coatings in a similar fashion to Example 4.
E~YAMPLE 7
D 10 A 22 foot polyester fiberglass boat (Aqua Sport~ ;~
equipped wlth a 100 horsepower outboard engine was operated
at two different throttle settings between two buoys approx-
imately one mile apart. Average times required to travel
between buoys going in both directions were determined at
each throttle setting. The boat was then removed from the
water, the bottom was washed with $resh water and dried.
The polymer solution of example 4 was applied with a roller
to provide a dry coating thickness of 0.75 to 1.0 mil. "
The boat was replaced in the water and the speed
at the same throttle s~ttings between the buoys was deter-
mined. The following results were obtained.
Speed, knots Speed, knots
Throttle Settinq Before Coating After_Coatlng
low 10.5 12.0
medium 17.2 19.8
The results show a 13% reduction in drag resistance
at a speed of about 10 knots and a 15% reduction at the high- -
er speed.
EXAMPLE_8
The "apparent viscosity" of water at 23C. was
measured using a Brookfield RVT Syncrolectric viscosimeter
employing a ~1 spindle at 100 R.P.M. The value obtained was ;
t~ Gur~
-15- ,
~, : ~ , . .. .. . .
. `
11.1 centipoises. The spindle was removed, dried, and was
coated with the solution prepared in example 4 by dipping
and allowing the spindle to drain and dry. The coating
thickness was approximately 0.5 mil. The "apparent viscos~
ity" of water at 23C. was again measured at 100 R.P.M. us-
ing the coated spindle. A value of 10.7 centipoises was
obtained. The peripheral spleed of the #l spindle at 100
R.P.M. is approximately 0.6 mile per hour~ At this speed
i~`.:' ' .
approximately 4% reduction in frictional resistance or drag -
was obtained.
EXAMPLE 9
A 9 foot polyester-fiberglass dinghy was towed be-
hind a motor launch with a rope attached to a spring scale
having a capacity of ten kilograms. The dinghy was towed
at 25 knots. An average force of 8 kilograms was noted on
the scale~ The dinghy was then removed from the water, `
rinsed with fresh water and dried. The dinghy was then
brush coated with the polymer solution of example 4 to pro-
vide a 1.5 mil. coating, aftèr drying, the dinghy was again
towed at 25 knots~ An average force of 6.5 kilograms was
recorded on the scale. Thus, at 25 knots approximately 18%
-. . . ~ .
reduction in drag resistance was obtained.
EXAMPLE 1O
Using a high-shear mixer, 200 grams of triphenyl
lead acetate and 50 grams of titanium dioxide were disperséd
in 8 kilograms of the polymer solution prepared in example -
4. To the dispersion was added 2 kilograms of sec. butyl
alcohol. A #l spindle of a Brookfield vlscosimeter was
coated with the dispersion by dipping and allowing to dry.
An average coating thickness of 0.6 mil. was obtained. The
"apparent viscosity"of water was measured as in example 3.
16-
A value of 10.5 centipoises was obtained. The coating was
removed from the spindle and the "apparent viscosity" was
again determined. A value of 11.0 centipoises was obtained~
The coating composition prepared in example 10
was employed on sailing craft, both of the wood hUll type
; and polyester-fiberglass laminate type to provide a fouling
resistant drag reducing coating.
EX~PLE_ll
Example 4 was repeated using a monomer charge of
40 lbs. of hydroxypropyl acrylate and 160 lbs. of hydroxy-
ethyl methacrylate. A conversion cf 85% was achieved after
7 hours. ~he procedure of example 8 was repeated using this
solution. Similar results were obtained. The solution of
example 11 was also coated on the bottom of a metal bottom-
ed motor launch to provide a drag reducing coating.
EXAMP~E 12
The procedure of example 11 was repeated replacing
the hydroxypropyl acrylate by 40 lbs. of acrylamide. Simi-
lar results were obtained.
EXAMPLE 13
To 500 grams of the coating dispersion of example
10 was added 2 grams of ethylene dimethacrylate (ethylene
glycol dimethacrylate), 1 gram-of benzoyl peroxide and 0.4 -
gram of ~,N-dimethyl aniline. The coating was immediately -
applied to a polyester-fiberglass laminated boat hull sur-
face. After drying and standing at 75F. ~about 24C.) for -
two hours the coating merely swelled but did not dissolve in
alcohol. The resulting coating was tougher when water swol-
len than the coating of example 10. It was also effective
as a fouling resistant drag reducing coating for the boat
bottom.
-17-
A number of antifouling experiments were carried
out using the hydrophilic polymers of the present invention.
After six months of testing on polyester resin panels the
best results were obtained us,ing triphenyl lead acetate as
the active antifouling ingredient. The results were also
superior to using the antifouling agent in formulations
which did not include the hydrophilic polymer.
Most antifouling compositions now used on ocean~
going vessels are based on the use of cuprous oxide pigmentl -
0 h relatively inert material. A large proportion of the cup-
rous oxide is not effectively used because it is encapsul-
ated in the resin and is unavailable unless the resin it-
self breaks down. A second disadvantage of cuprous oxide is
that it can induce galvanic corrosion. In addition, because
of its dark color, it is unsatisfactory as an antifouling
ingredient or decorative finishes.
The United States ~avy is, of course, interested
in antifouling finishes. It would like to have a 2-1/2 year `~
minimum, but finds that cuprous oxide coatings last from 12
18 months. Another market for effective systems is on tank-
ers and large freighters. The operators are constantly seek-
.
ing ways to decrease fouling because even a small amount of '
extra drag on the hull makes an appreciable difference to -
the efficiency of the vessel, which has an important effect
on the economics, particularly in tanker operations. In ad-
dition, there is a need for periodic removal from service
for bottom cleaning.
During the past decade a number of organometallic
and organic pesticides have been found to exhibit high ac- ~ ;
tivity against a broad spectrum of marine fouling organisms.
Economic utilization of these chemical anti-foulants in
shipbottom formulations has not been successfully accomplish
- i - - : . . ~,
: .. . - : , ~ ,., - .,, ~ .... . .
ed, however, primarily because of the encapsulation prob-
lem. The new anti-foulants are all several times more
potent than cuprous oxide, but their relatively high cost
dictates that they be employed at a fraction o~ the normal
concentratlon of the latter cuprous oxide. Continuous con-
tact between toxicant particles in the paint fllm is not
maintained at these relatively low concentrations, so that
the toxicants are not even utilized as efficiently as cup-
rous oxide, which in turn is also partially inactivated by
encapsulation. Modification of the paints with inert ex-
tender pigments or water-soluble resin constituents improves
the efficiency of toxicant utilization, but degrades the
physical integrity of the paint films to an intolerable de-
gree, To date, the most successful compromise is represent-
ed by blends or organometallic anti-foulants with cuprous
oxide to obtain durability and high potency. However, such
blends eliminate the two ma~or benefits offered by organlc
and organometallic antifoulantsS freedom from the galvanic
corrosion ha~ard of cuprous oxide, and flexibility of decor-
atlve pigmentation.
The use of hydrophilic water insoluble polymers ofthe present invention reduces the problem of encapsulation
of active~ anti-foulants in impermeable resin systems due to
the water swellable nature of the hydrophilic film. ~n
other acrylic resins and in other types of resin systems,
solid organic and organometallic anti-foulants do not demon-
strate any significant activity unless their concentration
in the film exceeds a threshold of about 25% by weight of
the resin. In the systems of the present invent~on activity
at much lower concentrations is noticed indicating that the
hydrophilic resin does not impermeably encapsulate the toxi-
cant particlés.
--19--
In the following examples, 14 - 16, Hydron-S is
hydroxyethyl methacrylate homopolymer. Hema ls an abbre-
viation for hydroxyethyl methacrylate.
EXAMPLE 14
This series of experiments was designed as an at-
tempt to determine whether ox not one of a variety of toxi-
cants showed any activity against marine organisms when in-
corporated into unmodified Hydron-S films. Accordingly,
ethanol solutions of Hydron-S containing concentrations of
2 3~/O of the active ingredients were applied to panels and ~ -
immersed at a Miami Beach test facility. Three toxicants
of different chemical type were selected: Hex~chlorophene
(Gll), tetrachloroisophthalonitrile (DAC-2787) and triphenyl
lead acetate (TPLA~. These solutions, which contained 14%
Hydron, were applied by brush to panels of glass-reinforced
polyester laminate which has been sanded to give a clean ;
surface. The details of the formulations are given in
TabIe 1.
These panels were observed at monthly intervals.
After the first period, all three of the formulations showed ;
some activity against marine organisms. The resin itself
was inactive, as demonstrated by the control sample which ~
rapidly became fouled. The Gll-containing series showed ;-
good protection with the exception of the panel containing
the 2% active ingredient (the lowest level). DAC-2787 was
described as moderately active while TPLA exhibited a de-
gree of control described as "startling". The films were
completely free of slimes and silt, as well as macrofouling.
In all cases, the physical integrity of the film was good.
This was highly encouraging, since organolead compounds have
not demonstrated useful levels of protection in coatings
* trademarkS
-20-
,~.
even though they are known to have broad-spectrum activity
in sea-water when leached out of porous blocks.
After five months' immersion, the Gll and DAC-
2787 panels were removed because all had fouled extensively.
However, the TPLA series was still performing well, and af-
ter six months the two films containing the most concentrat-
ed quantity of active ingredient ( l~/o to 32%~ were still `
rated as 10~/o effec~ive at this time, the film containing
6% TPLA was rated 92%~ the 4% film 84%, and the 2% coating,
36%. ~omplete results are summarized in Table 2
-21~
'1'
4~
TABLE 1 ~l
HYDRON-S FORMULATIONS, FIRST SERIES `
Formulation
_ No.Hydr_n-_ G 11 DAC-2787 TPLA E~OH
5 A (Control 13.8 - ~ ~ 86.2
lB 13.7 0.3 - - 86.0 -, -
lC 13.7 0.6 - - 85.7
lD 13.6 1.2 - - 85.2 ,~
lE 13.4 2.6 - - 84.0
10 lF 13.0 6.1 - - 80.9
2B 13.7 - 0.3 - 86.0
2C 13.7 - 0.6 - 85.7 , ~
2D 13.6 - 1.2 - 85.2 , ;
2E 13.4 - 2.6 - 84.0
15 2F 13.0 - 6.1 - 80.9 ; -
3B 13.7 - - 0.3 86.0
3C 13.7 - - 0.6 85.7
3D 13.6 _ _ 1.2 85.2
3E 13.4 - - 2.6 84.0
20 3F 13.0 - - 6.1 80.9 ,,
TA,BLE 2 ,
S,UMMARY OF BEHAVIOR R~PORTS OF EXPERIMENTAL SURFACES -~
(Plates Immersed March 15 - Hydron-S Brush
, ~oatings Containing Triphenyl Lead Acetate)
25 Anti- "
foulants Code _ ,Overall Ratin~, % _
May June July Au~st S~E~tember
None A ~7 0 0 0 0
TPLA, ~h3B 10071 42 36 36
30 TPhA, 4%3C 10092 90 90 8
TPLA, 8%3D 10095 93 92 92 -~
TPLA, 16% 3E100 100 100 100 100
TPLA, 32% 3F100 100 100 94* 100
* Attributed to green algae which attached during prolific
growth period but which did not persist. -`
Physical condition of all coatings was rated "good",
without physical defects, at time of September report.
.
--~2-- ~ `
.
EXAMPLE 15
Triphenyl lead acetate (TPLA) tests were also car-
ried out at four concentrations from 2 to 16% by weight in
Hydron-S and also in two copolymers (9~/0 Hema-10/O methyl
methacrylate and 60~/o Hema-40~fi methyl methacrylate. The co-
polymers have lower levels of sea-water permeability than
Hydron-S. These coatings were applied by both brush and
doctor-blade techniques. 8" x 10" aluminum alloy panels
were employed in the testing of effectiveness against foul-
ing. After one month the Hydron-S formulations performed
better than the copolymers. Pigmentation of the Hydron-S
did not detract from its performance.
-23-
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-24- ~
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TABLE 4
TP~ IN HYDRO~-S A~D 2 COPOLYMERS IMMERSION TEST RESULTS
% PAINT PANEL
POLYMER TPLA ##* ONE MD~TH
Physical % Rating
Condition O.P.
Hydron-S 2 1l-l/c Good 95
1-l/b Good 100
1-2/c Good 100
1-2/b Good 100
4 22-1/c Good 100
2-1 ~ Good 100
2-2/c Good i00
2-2/b Good 100
158 33-1/c Good 100
3-1/b Good 100
3-2/c Good 100
3-2~b Good 100
16 44-1/c Good 100
4-1/b Go~d 100
4-2/c Good 100
4-2 ~ Go0~` 100
90/10 2 55-l~c Blistèring 98
5-1/b Good 100
5~c Good 100
5-2/b Blistering 80
4 66-1/c Blistering 95
6-l~b Blistering 70
6-2/c Good 100
6-2/b Blistering 65
8 77-1/c Good 100
7-1/b Blistering 40
7-2/c Blistering 90
7-2 ~ BliStering 20
16 88-1/c Blistering 70
8-1/b Blistering 35
8-2/c BlisteringO 50
8-2,~b Blisteringq 30
..... - - ;.
60/40 2 99-1/c Blistering, Flaking 25 .l
9-1 ~ Blis~eFing 95 ;,`
9-2/c Bllstering t Flaking 35
9-2/b GQod 100 ;
1010-1/c Bl`istering, Flaking 70 ~ : :
10-1/b Good 100 ~` .
10-2/c ~ot Prepared
10-2/b Good 100
811 11-1/c Blis~:ing, Flaking ;~
(Corro~ion erUptions
on portions ~f bare :
aluminum) 85
~1-1 ~ Good 100 :
.
..
-25-
,
'..'. ::
.,
TABLE 4 - Cont'd
% PAINT PANEL
TPLA # #* ONE MONTH
j . .
Physical % Rating
- 5 Condition O.P.**
60/40 11-2/c Blistering, Flaking -;
(Corrosion eruptions
on portions of bare
aluminum) 25
11-2/b Good 100
16 12 12-1/c Not prepared
12-1/b Good 100 ;
12-2/c Not prepared
12-2/b Flaking 75 -
* c c cast, b = brushed.
** O.P. = Overall Performance
~ EXAMPLE 16
In another series of experiments, aluminum panels
were prepared from Hydron-S solutions containing the follow-
ing antifoulants:
Test ,i~
Panel
~esig-
na_ion _ Antifoulant _ _ _
25 A. Bis(tri-n-butyltin) oxide, "TBTO"
B. Triphenyltin chloride, "TPTCI"
C. Tributyltin fluoride, "TBTF"
E. Triphenyllead chloride, "TPLC" - ~'
F. Triphenyllead laurate, "TPLL" *
G. 1,2,3-Trichloro-4,6-dinitrobenzene, "Vanicide PB"
H. Saturated solution of Vancide PB in TBTO, "PBTO"
(ca 20.5% PB) *
I. 10,10'-Oxybisphenoxarsine; "SA-546" -
J. Mercurous chloride, Powder
35 K. Cuprous oxide, Grade AA
The formulations containing these antifoulants are
shown in Table 5, and the results after one month's immer-
sion in Table 6. Again, these results are from tests in sea-
water at Miami, Florida.
,
Panels K4 and K16, each with cast and brushed films
cbntaîning cuprous oxide on aluminum, were expected to show
galvanic corrosion. Since cuprous oxide is of importance
* trademark
-26-
'1:2
- - . ~ - ., ., .. - . . .
for comparison, additional K4 and K16 films were applled
to glass-reinforced polyester panels. K4 replicates were
brushed, and K16 cast because only the latter panels were
flat enough to permit accurate film draw-down.
A number of the formulations how considerable
interest, not only because of the protection afforded, but
also because of the sizeable content o pigments.
. :
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-27-
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-28-
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TABLE 6 -
HYDRO~-S SYSTEM CO~TAI~ING 4 & 16% OF VARIOUS
_ANTIP~ULA~TS IMMERSION TEST RESULTS _
:
ANTIFOULA~T PAI~T~ PA~EL ~* O~E MDNTH
Physieal % Rating
Condition -.-F.
TBTO A/4A4.1/e Good 95
A4.1/b Good 95
A4.2/e Good 95
A4.2/b Good 95
A/16A16.1/e Soft 95
A16.1/b Soft 93
A16.2/e Soft 95
A16.2/b Soft 98
15 TPT CI B/4B4.1/e Good 100
B4.1/b Good 100
B4.2/e Good 100
B4.2/b Good 100
B/I6B16.1/e Soft 98
B16.1/b Soft 98
B16.2/e Soft 98
B16.2/b Soft 98
TBTF C/4C4.1/c Good 95
C4.1/b Good 95
C4.2/c Good 95
C4.2/b Good 95
C/16- C16.1/e Good 100
C16.1/b Good 100
C16.2/c Good 100
C16.2/b Good 100
TPL~ E/4E4.1/e Good 95
E4.1/b Good 95
E4.2/e Good 10Q
E4.2/b Good 100
E/16E16.1/e Soft 98
E16.1/b Soft 98
E16.2/e Good 100
E16.2/b Soft 98
40 TPLL F/4F4.1/e Good 95
F4.1/b Good 95
F4.2/c Good 95
F4.2/b Soft 95
F/16~F16.1/c Soft 98
F16.1/b Good 100
F16.2/c Soft 98
F16.2/b Good 100
Vanieide PB G/4 G4.1/e Good 91
G4.1/b Good 90
G4.2/c Good 89
G4.2/b Good 91
G/16 G16.1/c Good 95
G16.1/b Good 95
. . ,
-30-
.. ~ .. . . , ~, . , .
.
40~
TABLE 6 - Contld.
A~TI~OULANT PAI~T ~ PAMEL #* ONE MO~TH
Physical % Rating
Condition O.P.**
5 Vanicide PB G/16 G16.2/c Good 95
G16.2/b Good 95
PBTO H/4H4.1/c Good 95
H4.1/b Good 95
~4.2/c Good 100
H4.2/b Good 95
H/16 H16.1/c Good 100
H16.1/b Good 100
H16.2/c Good 100 `
H16.2/b Soft 95 `,
15 DOW SA-546 I/4I4.1/c Good 100 ';
I4.1/b Good 100 ~;
I4.2/c Good 100
I4.2/b Good 100 ;-~
I/16I16.1/c Good 100
I16.1/b Good 100 ~
I16.2/c Good 100 ~
I16.2/b Good 100 `
Mercurous J/4J4.1/c Good 100 `
Chloride J4.1/b Good 95 ~
J4.2/c Good 100
-J4.2~b Good 100
J/16J16.1/c Blisterlng 90 `
J16.1/b Blistering 99
J16.2/c Blistering 90
J16.2/b Blistering 99
- Cuprous K/4K4.1/c Corr. eruption 95
Oxide K4.1/b Good 95
K4.2/c Good 95
K4.2/b Good 95 ;,~
K/16K16.1/c Corr. eruption9~ `
K16.1/b Corr. eruption 99
K16.2/c Corr. eruption 99
K16.2/b Corr. eruption 99
* ~ ca~t, b = brushed.
**O.P. = Overall Performance.
In examples 14 through 16, the formulations con-
taining pigments were prepared on a paint mill. All were
applied (with the few exceptions indicatad) to 6061-T6 ano- `
dized aluminum alloy by doctor-blade coatlng or brushing.
In the following examples phr means parts per
hundred of resin.
~
-31-
.,
.,
.. . , . , ,. . . . .. , . ,; . . . .. .. .. ........ ,... . . , ~
Example 17
To a 10% aqueous solution of hydroxyethyl cellu-
lose was added 1.18 phr. (based on polymer) of ammonium
dichromate. A portion of the solution was coated on a pre-
weighed glass slide and allowed to dry and cure at roomtemperature. The weight of the dried coating was then de-
termined and it was placed in water over night. The coated y
glass was blotted free of suxface moisture and weighed.
The coating had picked up 397% of its dry weight of water.
A separate portion of the solution was used to
coat the streamlined dart as described below for determina- ~
tion of drag reduction. -
Example 18
Example 17 was repeated using hydroxypropyl cellu-
lose in place of hydroxyethyl cellulose with 1.12 phr. ofammonium dichromate. The dried, cured coating picked ~p
590% of its weight on immersion in water for 18 hours.
ExamPle 19
To a 10% solution of polyvinyl pyrrolidone in
Ethanol was added 2 phr. of ammonium persulfate as a 10~
aqueous solution. The solution was coated on preweighed
al~minum foil and allowed to dry at room temperature-. The
film picked up 15 times its dry weight of water after 18
hours of immersion.
Example ~ff
To a 10% aqueous solution of polyvinyl alcohol was
added 2.36 phr. of ammonium dichromate. A dried film picked
up 58.7% of its weight of~water on immersion for 23 hours-. ~;
- Example 2
A lO ft. vertical glass column, 6 inches in d`iam-
eter was equipped with an axially located electromagnet at
-32-
the top, an axially positioned guide line down the length of the column and
photo-electric cells coupled with a timing device at the bottom of the column.
A streamlined aluminum dart having an axial hole through the center was
positioned over the guide line. The column was filled with water. The dart
was held at the top of the column by the electromagnet. A single switch,
which turned off the current to the magnet releasing the dart, simultaneously
turned on the timer. rhe interruption by the falling dart of the light beam ~ -
between the photocells positioned at the bottom of the column turned off the
timer.
The dart was timed without having coatings applied thereto, and ;
was then timed with various coatings applied to its surface. ;~
The average results (10 trials) obtained with the uncoated dart ,7''' ' '''
and the dart with the coatings of examples 17 - 20 are as follows:
Surface % H20 Drop Time Speed
Coating Material in film ~Seconds)Increase %
None Aluminum 1.217
Ex. 17 Hydroxyethyl 403 1.183 2.8
Cellulose .
Ex. 18 Hydroxypropyl 593 1.179 3.1
Cellulose
Ex. 19 Polyvinyl 1520 10180 3.0 ;
Pyrrolidone
Ex. 20 Polyvinyl 57.8 1.176 3.4
Alcohol
In place of the hydroxyethyl methacrylate polymer solution of
example 4 to coat sailboats and motorboats there can be used the hydroxyethyl
cellulose solution of example 17, the hydroxypropyl cellulose solution of
example 18, the polyvinyl pyrrolidone solution of example 199 or the poly-
vinyl alcohol solution of example 20. "~
Similarly, in place of the Hydron-S and the copolymers employed in
examples 14, 15 and 16 there can be used the same weights of the polymers of
examples 17, 18, 19, 20 or 21.
..
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- 33 -
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