Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 3
BACKGROUND OF THE INVENTION
It has been found that many types of nettings, exposed
to sea and lake waters, experience heavy levels of clogging due
to algae and inver-tebrates. Such clogging limi-ts the Elow of
water and deposited organisms in the enclosed area with con-
comitant weight increases as high as 1000 percent. Such a
weight increase results in the sinking of the supported netting
and fish escape as well as making it practically impossible to
raise the netting for cleaning. In some instances, the cutting
away of netting is necessitated resulting in the loss of net-ting.
In addition to netting losses, fish may also be lost or harmed.
Salt and freshwater aquaculture systems have traditlonally been
plagued by heavy fouling on nets, cages, intake pipPs and aera-
tion systems. Nets particularly have suffered from heavy
incrus-tation making them inordina-tely heavy, and eventually
incapable of permit-ting water, flow-through. Natural food
penetration, acceptable oxygen levels and detritus removal are
severely restricted, leading to poor crop yield. Labor for
frequent cleaning adds high costs and full cage utilization is
not possible because of cage rotation during cleaning. Anti-
fouling compounds have been used for centuries with only partial
success. Traditional an-ti-fouling coating treatments have
relied on copper and mercury compounds which are effecti~e anti-
~oulants but are hiyhly toxic and can be damaging to systems in
which live organisms are expected to survive.
A net finishing composition in a suitable 501ve~t
system has been proposed which when coated on a net substrate,
particularly a nylon net subs-trate of a mesh size of Ero~ 1/~
to 2~ inches, substantially improves the intecJrity o~ the net
substrate concommitantly improvinc~ seining ~ualities in terms
of improved daily catch. The net fishiny composition is com-
prised of a lo~ molecular weiyht, hi~ acetate content, vinyl
-- 1 --
3~2
chloride copolymer, a monomeric plasticizer and a polymeric
plasticizer. The molecular weight of the copolymer is from
20,000 to 65,000 and oE an acetate content of from 10-20
percent by weight. The plasticizers are present ln an amount
oE Erom 40 to 60 parts, preferably 50 parts per 100 parts of
-the copolymer with the ra-tio on monomeric plasticizer to poly-
meric plasticizer ranging from about 1:1 to 3:1, preferably
2:1.
In United States Patent No. 4,010,141 to Onozuka et al.
there is disclosed a plurality of tin compounds, and in parti-
cular dimethyl, n-alkyl tin esters of improved antifouling
characteristics. While such trialkyl tin esters have shown some
efficacy, such trialkyl tin esters are compatible with the plas-
ticizers in the resin and can readily leach out or can be locked
into the film after application to a netting substrate.
OBJECTS OF THE INVENTION
An objec-t of the present invention is to provide a net
antifouling composition exhibiting substantial efficacy over
extended periods of -time after netting application.
Another object of the present invention is to provide a
net antifouling composition readily applied to a netting sub-
strate.
Still another object oE the present invention is to
provide a net antifouling composition which does not delete-
riously affect -the fish catch.
Yet another object of the present invention is to pro-
vide a net antifouling composition which leaches out at a con-
trolled rate from the net substrate.
A further object of the present invention is to provide
a net antifoulin~ composi-tion having a soft enough finish and
being flexible which will not damage the fish when they brush
against the treated netting.
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; ~ ~
Still yet another object of the present invention is to provide
a net antifouling composition capable o-f lowering operating costs resulting
from reduced labor time in cleaning and maintenance of tlle netting.
~ nother object of the present invention is to provide a nc-~t
anti-Eouling composition red-lcible with water instead of -~lammable solvents
or tars allowing for simpler and safer application.
Still another object of the present invention is to provide a net
antifouling composition that does not wear off the netting abovc the water
line.
Yet another object of the present invention is to provide a net
antifouling comyosition capable of protecting a treated nct e~posed to sun-
ligh-t.
Still yet another object of the present invention is to provide
a net antifouling composition more resistant to abrasion.
SU~IMARY OF TIIE INVeNTION
These and other objects o-E the present invention are achieved by
a net antifouling compos:ition ~or use 011 nettings and comprised of from 2 to
10 percent, preferably 3-6 percent by weight of a tri-n-butyl tin ester
selected from the group consisting o~ tri-n-butyl tin linoleate, bis(tri-n-
butyl) tin succinate, tri-n-butyl tin benzoate, bis tri-n-butyl tin salicy-
late and mirctures thereof in an organic solvent system or a water base
system, preferably a water base system~ for controlling algac and inverte-
brate growtll. In one aspect of the presellt invelltion, the tri-n-butyl tin
esters may be admi~eci with a net finishing composition as clescribed above.
BRIEF DESCRIPTION OF TIIE DRAWING
~n understanding of tllc invention will be facilltated by re~er-
ence to the photograplls on the dra~Ying and the accompanying detailed
description, wherein:
Figure I are photograplls of a fish netting treated with the
present invelltion; and
Figure _ are photograplls of untreated fish netting.
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lZ;~73(~Z
DETAILED DESCRlPll[ON O~ THE INVENTION
The tri-n-butyl tin esters used in the present invention are selected from the
group consisting of tri-n-butyl tin linoleate, bis(tri-n-butyl) tin succinate, tri-n-butyl
tin benzoate, tri-n-butyl tin salicylate and mixtures thereof. The tri-n-butyl tin ester
is ~dded in an amount of from 2 to 10, preferably 3-6 percent by weight to either an
organic sol~ent system or a water base system, preferably a wQter base system.
The essential components of a concentrate forming the preservative system of
the present invention are a tri-n-butyl tin ester and filler such as clay. The tri-n-
butyl tin es-ter ~nd filler are mixed in a ratio of 1 part of tri-n-butyl tin ester to 1-4
parts of filler and more preferably 1 part of bis tri-n-butyl tin ester to 2-3 parts of
filler. The filler acts as a buffering agent and helps releases the toxicant, tri-n-butyl
tin ester. In preparation for treating the netting, the preservative system concen-
trate is added to a water base or organic base solvent system.
The essenti01 components of the water base sol~ent system are the tri-n-butyl
tin ester and filler, such as clay concentrate in addition to binders such as
acry~ic/vinyl latexes, styrene latex, styrene/acrylic latexes, vinyl chloride, vinyl
chloride acetate, acrylonitrile latexes and the like~ Also added to the water based
solvent system are wetting agents, suspending agents, coaleseent agents, pigments
and water.
If an organic base solvent system is used, the essential eomponents of the
organic base system are tri-n-butyl tin ester, a solution resin, such as a vinyl chloride
- vinyl acetate co-polymer, plasticizers, stabili2ers, pigments and organic solYents.
In one embodiment of the present invention the tri~n-butyl tin ester seleeted
from the group consisting of tri-n-butyl tin linoleate, bis (tri-n-butyl tin succinate,
tri-n-butyl tin benzoate, tri-n-butyl tin salicylate and mixtures thereof, is added in an
amount rom 2 to 10 percent by weignt to a net finishin~ composition comprised of a
resin system dissolved in a solvent system, such that th~ solids content of the
resulting composition of matter is not iess th~n about 20% by weight, and between
2û% to about 50% solids, with a preferable solids range of abou~ 30 to 40~ by weight.
~7302
A method of applieation of the net antifouling composition of the present
invention is achieved by dipping a net in a tank containing the preservati~e system
admixed with a solvent system. When the net is dipped in the tank that portion of the
net dipped should be allowed to set in the tank for about 10 seconds to about 30minutes with a preferable time limit being approximately 3-5 minutes.
Although the net treated with the preservative system in a solvent system can beutilized when it becomes dry to the touch it is preferable that the net antifouling
composition be allowed to cure on the net. The purpose of curing allows for the
~aporization or evaporation of the solvent system and the absorbtion of the
preservative system into the net. The preservative system should be allowed to cure
from about 4 to 96 hours, with a preferable curing time of 48 to 72 hours prior to use.
It has been fcund that a net treated with the antifouling composition having a
minumum weight pick u~ of 30% on the net of the present invention results in a
coated net exhibiting after a long term test period an increase of weight of only
about 5 percent as ~ompared to a control net (without the orgnno tin ester coating)
exhibiting a weight increase of greater than 500 percent.
Referring to FIGS. 1 and 2, there are shown photographs of treated and untreatednets with the net antifouling composition demonstrating the efficacy of the present
invention. Such efficacy has been repeatedly demonstrated whether in the fresh
waters of tha Great Lakes Region or the salt water of the Florida Keys, the Gulf,
Cepe Hatter~, ova Scotie ~nd the like.
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E~AMPL~ OP THR INY~NTION
The following examples are illustrative of the present invention:
E~AMPL~ 1
A nylon fish net is treated in Q water based net antifouling composition of the
components as set forth in Table I, below:
TABLE I
COMPONENTS PARTS
Water 42.00
5Odium Tri Poly Phosphate .20
Non-Ionic Surface Active Agent .20
Hydroxy Ethyl Cellulose 50
Tri-n-butyl tin linoleate 5.30
China cl~y 13.35
Anti-Foaming Agent .25
Ethylene Glycol 1.10
Diethylene Glycol Mono Ethyl Ether 1.10
Pigments 3.00
Vinyl chloride acrylic copolymer latex 33.00
100.00
The solution i5 introduced into a trough at arnbient temperature. A fishin~ net
having a mesh si~e in the range of from .25 to 24 inches is continously introduced into
the trough and withdrawn, such that incrementAl sections of net r~main in the
solution of from 10 seconds to 10 minutes or can be dipped in a tank and Rllowed to
drain.
The antifouling composition costed on the net dries in flbout 4 to 6 hours. The
net antifouling composition i~ permitted to cure on the net for ~ period of
approximately 72 hours before net usa~e.
]e~MPLE ~
A nylon fish net is treRted in an or~anic solven~ b~sed net antifouling cornposi-
tlon hQving the following component~:
~L2X7~2
TA~LE II
COMPONENTS PARTS
Xylene-xylol(ortho) Aromatic 40.30
solvent
M.I.B.K. (methyl isobutyl ketone) 30.35
Icetone solvent
Polymeric plasticizer 2.80
dibasic acid and glycol
409/429 Monsanto Chemical
Di octyl/phthalate (DOP)
Di-2 ethyl hexy/hthalate) 2.45
Vinyl chloride-vinyl acetate 16.80
copolymer - resin
Ex: VC113/Borden Chemical
~SUV stabilizer .10
Black Pigment 4.10
8is (tri-n-butyl)tin succinate .81
Tri-n-8utyltin benzoate .96
~ 0
.
12Z~30;2
A net coated with the above referenced antl~ouling composition was submerged
in the ocean off of the British Coast along with a control net which was not treated
for a period of 22 weeks. The control net treated with the net antifouling
composi~ion had an initisl weight of 377 pounds prior to being deposited on the sea
floor. The untreated net ttreated without antifouling composition) had an initial
weight of 418 pounds prior to submersion.
Now referring to Fig. 1 there is s~own a photograph of the net treated with the
~ntifouling composition after it was removed from the sea floor. It was found toweigh 660 pounds after its remo~al. This was a weight increase of only 43.296.
Additionally, it was found that approximately 10% of the treated net was fouled, with
the primary fouling organism being hydrozoan.
Now referring to Fig. a, there is shown a photograph of the control net after its
remo~/al from the sea floor. I~pon removal it was found to weigh 1190 pounds, thus
having a weight increase of almost 185%. Approximately, 90q6 of the net was fouled
with th~ primary fouling organisms being hydrozoan, mussels and sea squirts.
While the invention has been described in connection with the exemplary
embodiment thereof, it will be understood that many modifications will be apparent
to those of ordinary skill in the art and thst this application is intended to cover any
adaptions or Yariations thereof. Therefore, it is manifestly intended that this
invention be only limited by the claims and the equivalents thereof.
