 |
Description  |
|
|
FIELD OF THE INVENTION
The present invention relates to an antifouling coating that contains a
polymer having polydimethylsiloxane groups and/or trimethylsilyl groups in
side chains.
BACKGROUND OF THE INVENTION
The bottoms of ships, buoys and other structures that are submerged in
seawater such as cooling water intake or discharge pipes are infested with
organisms such as barnacles, tube worms, mussels and algae that attach to
the surfaces of these structures and cause various troubles. It is routine
practice to prevent the attachment of these marine organisms by coating
the surface of the aforementioned items with antifouling paints.
Antifouling paints are roughly divided into two classes. The antifouling
paints of one class (A) employ antifoulants such as organotin copolymers
and cuprous oxide that are capable of preventing the attachment of fouling
organisms and have low solubility in seawater. Paints that employ
organotin compounds as antifoulants are shown in Japanese patent
Publication Nos. 21426/65, 9579/69, 13392/71, 20491/74, 11647/76 and
48170/77. The antifouling paints of the second class (B) do not employ any
antifoulants and will not dissolve in seawater; instead, they use silicone
rubbers that cure by the action of a catalyst or moisture to form a
crosslinked film. For instance, an antifouling paint that uses a curable
silicone rubber as a coating agent is shown in Japanese patent Publication
No. 5974/78. An antifouling paint that uses a mixture of a silicone oil
and an oligomer-like silicone rubber having a terminal hydroxyl group is
shown in Japanese patent application (OPI) No. 96830/76 (the term "OPI" as
used herein refers to a "published unexamined Japanese patent
application"). A mixture of a curable silicone rubber and a flowable
organic compound that does not contain a metal or silicon is shown in
Japanese patent application (OPI) No. 79980/78. A paint that serves to
prevent the attachment of fouling marine organisms is also shown in
Japanese patent Publication No. 3433/85 and this paint is composed of a
mixture of an oligomer-like low temperature curing silicone rubber (such
as ones available from Shin-Etsu Chemical Co., Ltd. under the trade names
of "KE 45TS" and "KE 44 RTV") and liquid paraffin or petrolatum.
The antifouling paints of class (A) are further divided into two
subclasses. In one subclass of such antifouling paints, the film-forming
resin does not dissolve in seawater and only the antifoulant dissolves in
seawater to prevent the attachment of marine organisms. The coatings
formed from this class of antifouling paints exhibit the intended effect
during the initial period of application but after the antifoulant on the
surface of the coating is lost as a result of its dissolution in seawater,
the antifoulant in the deeper area of the coating will gradually dissolve.
However, the dissolution rate of the antifoulant decreases as the depth of
the area in which it is present in the film of coating increases, and the
antifouling effect of the paint becomes insufficient in the long run.
In the second subclass of antifouling paints of class (A), both the
antifoulant and the film-forming resin dissolve in seawater. The
antifouling effect is achieved solely by the antifoulant or by a
combination of the antifoulant and the resin component (e.g., an organotin
copolymer) and, in either case, the surface of the coating dissolves in
seawater to continuously provide the antifouling film of coating with an
active surface. Therefore, the coating formed from this type of
antifouling paints is capable of maintaining the desired antifouling
effect over a longer period than the aforementioned first subclass of
paints (A). However, the effect of this type of antifouling paints is not
completely satisfactory because the film of coating they form is consumed
fairly rapidly. In addition, the antifouling paints that employ
antifoulants have one common problem in that the antifoulants have a
potential for polluting the sea and killing marine products such as fish
and shells.
Antifouling paints of class (B) are designed to prevent the attachment of
marine organisms by making use of the slipping property (low surface
energy) of the silicone rubber coating. However, these paints have the
following disadvantages associated with the mechanism of film formation
that involves the crosslinking of silicone rubbers after paint
application.
The first problem is associated with the curing of the applied coating. For
instance, when an antifouling paint of the type described in Japanese
patent Publication No. 3433/85 that employs a low temperature curing
oligomer-like silicone rubber that cures by the action of moisture in air
to form a film of coating is applied to a substrate, the crosslinking
agent incorporated to control the curing condensation reaction of the
silicone rubber is activated by the moisture or temperature of air to
cause premature curing of the surface of the coating. This retards the
curing of the deeper portion of the coating to produce an insufficiently
cured film which is most likely to blister or separate from the substrate.
Furthermore, the slow penetration of moisture into the bulk of the coating
prolongs the time required to achieve complete curing of the coating.
If the antifouling paint of the type described above is applied in a hot
and humid atmosphere, the hydrolysis of the crosslinking agent
predominates over the crosslinking reaction and the resulting coating does
not have a sufficient crosslink density to provide satisfactory
properties.
In a dry climate, the amount of aerial moisture is too small to cause
hydrolysis of the crosslinking agent and the applied coating will cure
very slowly. In order to avoid this problem, catalysts such as tin
compounds and platinum are sometimes used as curing accelerators but their
effectiveness is limited in cold climates.
The second problem concerns the case of top-coating. In the usual case, the
solvent in a paint for topcoating slightly dissolves the surface of the
undercoat to ensure good intercoat bonding. However, in the application of
the antifouling paint under consideration, the silicone rubber in the
first applied coating cures to such an extent that the solvent in a paint
for top-coating is not capable of dissolving the surface of the silicone
rubber to provide satisfactory intercoat bonding.
The third problem is related to pot life. The actual coating operation is
prolonged if the item to be treated is large in size or has a complex
structure. In addition, the operation may be interrupted by unexpected
rainfall. In view of these possibilities, antifouling paints having short
pot lives present great inconvenience in coating operations.
The fourth problem is associated with storage stability. Antifouling
paints, after being prepared, are stored until use and the duration of
such storage sometimes extends for a long period. Therefore, the
manufacture of paints that will cure by the action of moisture
necessitates the filling of their containers with a dry nitrogen gas. In
addition, once the container is opened, aerial moisture will get into
cause curing of the surface of the paint or an increase in its viscosity.
Paint that has undergone such changes is no longer suitable for use.
SUMMARY OF THE INVENTION
The present inventors made concerted efforts to develop an antifouling
coating that possesses none of the aforementioned disadvantages of the
conventional products and which yet exhibits superior antifouling effects.
As a result of these efforts, the inventors have succeeded in creating an
effective antifouling coating that does not use any antifoulant but uses a
specified polymer of the type which dries by solvent volatilization and
which has polydimethylsiloxane groups and/or trimethylsilyl groups in side
chains. Unlike the silicone rubber described above in connection with the
prior art, the polymer specified by the present invention dries by solvent
volatilization and hence is inherently free from the problems associated
with curing processes, cohesion of interlayers, pot life and storage
stability. What is more, the film formed from this polymer provides a
superior surface slipping property to ensure improved antifouling effects.
The present inventors have also found that further improvements in
antifouling effects can be achieved by incorporating a slipping agent such
as petroleum waxes, silicone oils, fats and oils in the specified polymer.
An object, therefore, of the present invention is to provide an
industrially useful antifouling coating that solves all of the problems
associated with the conventional antifouling paints and which yet achieves
much better antifouling effects.
In order to achieve this object, the present inventors conducted intensive
studies and have succeeded in preparing an antifouling coating that is
based on a polymer of the type which dries upon solvent volatilization.
This coating is free from all of the defects of the known antifouling
paints which employ a silicone rubber either alone or in combination with
a silicone oil or paraffin and yet produces a coating surface that has a
small enough angle of slip to exhibit better antifouling effects.
The antifouling coating of the present invention contains as its essential
components a polymer of one or more of the monomers A represented by
formula (1) and/or a copolymer which is composed of one or more of the
monomers A and one or more monomers B that are radical-copolymerizable
with said monomer A:
##STR2##
wherein X is a hydrogen atom or a methyl group; n is an integer of 2 to 4;
and m signifies the average degree of polymerization and ranges from 0 to
70.
If this polymer (hereinafter designated as polymer A) or copolymer
(hereinafter designated as copolymer AB) is used in combination with a
specified slipping agent, a further improvement in the antifouling effects
of the coating can be achieved without sacrificing the advantages
resulting from the use of polymer A or copolymer AB.
BRIEF DESCRIPTION OF THE DRAWING
FIGS. 1(A) and (B) are side views showing how to measure the slip angle of
the surface of the antifouling coating film.
DETAILED DESCRIPTION OF THE INVENTION
Monomer A used in the present invention for preparing polymer A or
copolymer AB is an unsaturated monoester represented by formula (1) which
has a polydimethylsiloxane group (m>1) or a trimethylsilyl group (m=0) in
the molecule. In formula (1), m is specified to be within the range of 0
to 70; if m is greater than 70, the polymerizability or copolymerizability
of monomer A is decreased to an extent which renders it difficult to
attain polymer A or copolymer AB in a form that is capable of producing a
uniform film of coating. In formula (1), n is specified to be within the
range of 2 to 4. If n is less than 2, the linkage at the esterforming
portion of monomer A becomes weak and during polymerization or during the
use of the resulting coating the ester linkage dissociates to either
reduce the antifouling effect of the coating or shorten the duration of
time during which it exhibits the intended antifouling effect. If n is
more than 4, the polymer becomes too soft to form a satisfactory film of
coating.
Examples of the monomer A represented by formula (1) are hereinafter listed
by their specific names: illustrative compounds having a trimethylsilyl
group include trimethylsilylethyl acrylate or methacrylate,
trimethylsilylpropyl acrylate or methacrylate, and trimethylsilylbutyl
acrylate or methacrylate; illustrative compounds having a
polydimethylsiloxane group include polydimethylsiloxanethyl acrylate or
methacrylate (m.ltoreq.70), polydimethylsiloxanepropyl acrylate or
methacrylate (m.ltoreq.70), and polydimethylsiloxanebutyl acrylate or
methacrylate (m.ltoreq.70).
These compounds as examples of monomer A are readily available commercially
or can be attained by synthesis. Exemplary methods of synthesis include: a
method wherein acrylic acid or methacrylic acid is reacted with an
alkylene glycol to form a corresponding ester, which then is condensed
with a trimethylsilyl or polydimethylsiloxane compound; and a method
wherein an ester of acrylic or methacrylic acid with an allyl alcohol is
subjected to an addition reaction with a trimethylsilyl or
polydimethylsiloxane compound.
Monomer A may be copolymerized with a radical polymerizable monomer B to
form copolymer AB, and illustrative compounds that can be used as monomer
B include: methacrylate esters such as methyl methacrylate, ethyl
methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and
2-hydroxyethyl methacrylate; acrylate esters such as ethyl acrylate, butyl
acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; maleate
esters such as dimethyl maleate and diethyl maleate; fumarate esters such
as dimethyl fumarate and diethyl fumarate; and styrene, vinyltoluene,
.alpha.-methylstyrene, vinyl chloride, vinyl acetate, butadiene,
acrylamide, acrylonitrile, methacrylic acid, acrylic acid and maleic acid.
Radical polymerizable monomer B serves as a modifying component that
imparts desirable properties to the antifouling coating; this monomer is
also useful for the purpose of attaining a polymer that has a higher
molecular weight than the homopolymer of monomer A. The amount of monomer
B used is appropriately determined in consideration of the properties it
imparts and the antifouling effect achieved by monomer A. Generally, the
ratio of monomer B is not more than 90 wt%, preferably not more than 70
wt%, of the total amounts of monomer A and monomer B. The reason for
selecting this range is that if the proportion of monomer A in copolymer
AB is at least 10 wt%, especially at least 30 wt%, the intended
antifouling effect can be satisfactorily achieved by monomer A.
Polymer A or copolymer AB may be formed by polymerizing monomer A either
alone or in combination with monomer B in the presence of a radical
polymerization initiator in accordance with routine procedures. Methods of
polymerization include solution polymerization, bulk polymerization,
emulsion polymerization and suspension polymerization. Illustrative
radical polymerization initiators are azo compounds such as
azobisisobutyronitrile and triphenylmethylazobenzene, and peroxides such
as benzoyl peroxide and di-tert-butyl peroxide.
The polymer A and copolymer AB to be prepared by the methods described
above preferably have weight average molecular weights within the range of
1,000 to 150,000. If the molecular weight of the polymer A or copolymer AB
is too low, it is difficult to form a dry uniform film. If the molecular
weight of polymer A or copolymer AB is too high, it makes the varnish high
viscous. Such a high viscosity varnish should be thinned with a solvent
for formulating a coating. Therefore, the resin solids content of the
coating is reduced and only a thin dry film can be formed by a single
application. This is inconvenient in that several applications of coating
are necessary to attain a predetermined dry film thickness.
In accordance with the present invention, a slipping agent may be used in
combination with polymer A and/or copolymer AB. Any compound may be used
as this slipping agent so long as it is capable of substantially
maintaining or lowering the small angle of slip that is possessed by the
surface of the film of coating formed from the polymer A and/or copolymer
AB. The following five classes of materials that impart slip properties to
the film of coating may be used as slipping agents in the present
invention.
(1) petroleum waxes of the class specified in JIS K 2235, which include
paraffin wax e.g., having a melting point of from about 48.9.degree. C.,
microcrystalline wax e.g., having a melting point of about 60.degree. C.
or over and petrolatum e.g., having a melting point of from about
45.degree. C. to 80.degree. C.;
(2) liquid paraffins of the class specified in JIS K 2231, which are
illustrated by equivalents to ISO VG 10, ISO VG 15, ISO VG 32, ISO VG 68,
and ISO VG 100 e.g., having a kinetic viscosity of from about 9 to 110
centistokes at 40.degree. C.;
(3) silicone oils having kinetic viscosities of not more than 55,000
centistokes (cSt) at 25.degree. C., which are illustrated by those
available from Shi-Etsu Chemical Co., Ltd. under the trade names of KF 96
L-0.65, KF 96 L-2.0, KF 96-30, KF 96 H-50,000, KF 965, KF 50, KF 54 and KF
69; dimethyl silicone oil is most common but other silicone oils such as
methylphenyl silicone oil may also be used;
(4) fatty acids or esters thereof having melting points of -5.degree. C. or
higher and not less than 8 carbon atoms; illustrative fatty acids that
satisfy these requirements include caprylic acid, capric acid, lauric
acid, myristic acid, palmitic acid, stearic acid, cerotic acid, montanic
acid, melissic acid, lauroleic acid, oleic acid, vaccenic acid, gadoleic
acid, cetolic acid, selacholeic acid, and juniperic acid; illustrative
esters of these fatty acids include stearyl stearate, butyl laurate, octyl
palmitate, butyl stearate, isopropyl stearate, cetyl palmitate, ceryl
cerotate, myricyl palmitate, melissyl melissate, spermaceti, bees wax,
carnauba wax, montan wax, Chinese insect wax, tristearin, tripalmitin,
triolein, myristodilaurin, caprylolauromyristin, stearopalmitoolein,
monostearin, monopalmitin, distearin, dipalmitin, tallow, lard, horse fat,
mutton fat, cod-liver oil, coconut oil, palm oil, Japan tallow, Kapok oil,
cacao butter, Chinese vegetable tallow, and illipe butter;
(5) organic amines having an alkyl or alkenyl group containing 12 to 20
carbon atoms, such as dodecylamine, tetradecylamine, hexadecylamine,
octadecylamine, oleylamine, tallow alkylamines, coco-alkylamines, soybean
alkylamines, didodecylamine, di-tallow-hydrogenated alkylamines,
dodecyldimethylamine, coco-alkyldimethylamine, tetradecyldimethylamine,
hexadecyldimethylamine and octadecyldimethylamine.
The slipping agents specified above are used in amounts that should be
properly determined in consideration of the drying properties, adhesion to
substrate and antifouling effects offered by the polymer A and/or
copolymer AB. Generally, the slipping agents are used in amounts of 1 to
70 wt%, preferably 5 to 50 wt%, of the total amount of polymer A and/or
copolymer AB and the slipping agent.
As will be apparent from the foregoing description, the antifouling coating
of the present invention is typically used in the form of a solution
wherein polymer A and/or copolymer AB together with the slipping agent
specified above are dissolved in an organic solvent. Therefore, practical
considerations indicate that it is preferred to prepare polymer A and/or
copolymer AB by solution polymerization or bulk polymerization.
Examples of the organic solvent that can be used to prepare a solution of
polymer A and/or copolymer AB which optionally contains the slipping agent
include: aromatic hydrocarbons such as xylene and toluene; aliphatic
hydrocarbons such as hexane and heptane; esters such as ethyl acetate and
butyl acetate; alcohols such as isopropyl alcohol and butyl alcohol;
ethers such as dioxane and diethyl ether; and ketones such as methyl ethyl
ketone and methyl isobutyl ketone. These organic solvents may be used
either alone or in admixture.
The organic solvents are preferably used in such amounts that the
concentration of polymer A and/or copolymer AB in the solution generally
ranges from 5 to 80 wt%, preferably from 30 to 70 wt%. The solution
preferably has a viscosity of 1 to 10 poises at 25.degree. C. in order to
facilitate the film formation from the solution.
The antifouling coating of the present invention thus prepared may
optionally contain colorants that are intoxic and will not dissolve in
seawater. Suitable colorants are pigments such as red oxide and titanium
dioxide, and dyes. The coating agent may also contain conventional
antisagging agents, antiflooding agents, antisetting agents, and
antifoaming agents.
The surfaces of structures to be submerged in seawater are treated with the
antifouling coating of the present invention to form an antifouling film
of coating. The procedure cf such treatment is simple; for instance, a
solution of the coating is applied to the surface of the structure of
interest by an appropriate means and the solvent is removed by evaporation
at ordinary temperatures or under heating. This suffices for the purpose
of forming a uniform film of antifouling coating that exhibits good slip
properties.
The polymer A and/or copolymer AB used in the present invention has the
polydimethylsiloxane group and/or trimethylsilyl group that derives from
monomer A and because of these groups, the polymer A or copolymer AB is
capable of forming a film of coating that has a very slippery surface.
Therefore, the film itself of the coating formed from such polymer or
copolymer has the ability to physically prevent the attachment of fouling
marine organisms.
Radical polymerizable monomer B in copolymer AB serves as a modifying
component that imparts an adequate level of slip properties to the surface
of the film of coating formed from copolymer AB. Monomer B is also
effective in forming a polymer having a higher molecular weight than a
homopolymer of monomer A or in controlling the hardness and strength of
the film of coating.
The slipping agent which may be used in the present invention in
combination with polymer A and/or copolymer AB is an important component
since the combination ensures prolonged antifouling effects in a marine
environment where the growth of fouling organisms is active. The present
inventors consider that this enhanced retention of antifouling effects is
due to the maintained slip properties of the film of antifouling coating
that is achieved by the surface lubricating action of the slipping agent
and by the ability to retard the deterioration of the film formed from
polymer A and/or copolymer AB.
The polymer specified in the present invention for use in an antifouling
coating is inert and forms a thermoplastic film of coating that dries upon
solvent volatilization and which is insoluble in seawater. Therefore, the
antifouling coating of the present invention has the following advantages
over the conventional antifouling paints.
First, it is stable and can be formulated in a paint without experiencing
any risk of deterioration by reaction with other active ingredients. The
container of the paint does not need to be filled with an inert gas
because it has an unlimited pot life.
Secondly, the paint dries quickly after application and yet will not
blister or separate from the substrate because it will not experience any
inadequate curing in the deeper area of coating and the drying speed is
not affected by moisture or temperature.
Thirdly, the film of coating formed from the coating of the present
invention can be topcoated with a similar or dissimilar paint without
sacrificing the strength of intercoat bonding.
Fourthly, the film formed from the coating of the present invention will
not be eroded by contact with seawater and therefore retains good
antifouling effects over a prolonged period. The superior antifouling
effects of the film are supported by the fact that its surface has an
angle of slip that is much smaller than that exhibited by the film of
coating formed from the conventional antifouling paint employing a
crosslinked silicone rubber.
The present invention is hereinafter described in greater detail with
reference to the following examples of polymer preparation, working
examples and comparative examples, wherein all parts are on a weight
basis. The data for viscosity were obtained by the measurement of bubble
viscosities at 25.degree. C., and the data for molecular weights are
indicated in terms of weight average molecular weights as measured by GPC
(gel permeation chromatography).
PREPARATION EXAMPLES 1, 2, 4, 5 AND 7 TO 9
A flask equipped with a stirrer was charged with a cooking solvent a (for
its name and amount, see Table 1), which was heated to a predetermined
temperature for reaction. A liquid mixture of monomer A, monomer B and a
radical polymerization initiator a (for their names and amounts, see Table
1) was introduced dropwise into the flask with stirring over a period of 2
to 3 hours. After completion of the addition, the contents of the flask
were held at the predetermined temperature for reaction for a period of 30
minutes. Subsequently, a mixture of a cooking solvent b and a radical
polymerization initiator b (for their names and amounts, see Table 1) was
added dropwise over a period of 20 hours, and the resulting mixture was
held at the predetermined temperature for 3 to 5 hours with stirring so as
to complete the polymerization reaction. Finally, a solvent was added to
dilute the reaction product. By these procedures, copolymer solutions I,
II, IV, V, VII to IX were prepared.
PREPARATION EXAMPLES 3 AND 10
A heat- and pressure-resistant vessel was charged with a monomer A, monomer
B and a radical polymerization initiator a in accordance with the
formulations shown in Table 1. The vessel was completely closed and the
contents were heated to a predetermined temperature for reaction under
shaking. Thereafter, the shaking of the vessel was continued for 2 hours
until polymerization reaction was completed. A diluting solvent was then
added and shaking was continued for an additional 3 hours to obtain a
solution. By these procedures, copolymer solutions III and X were
prepared.
PREPARATION EXAMPLE 6
A flask equipped with a stirrer was charged with a cooling solvent a, a
monomer A and a radical polymerization initiator a and the contents of the
flask were heated to a predetermined temperature for reaction with
stirring. The stirring of the reaction mixture was continued at the
predetermined temperature for 3 hours to obtain a copolymer solution VI.
TABLE 1
__________________________________________________________________________
Preparation Example
Composition (parts) 1 2 3 4 5 6 7 8 9 10
__________________________________________________________________________
Cooking Solvent a
Butyl acetate 120 180 30 180
Xylene 50 15 100 120
Ethylene glycol monoethyl ether 45
Monomer A (*1) 120 180 55 15 25 100 36 120 180 13
(See Note below for its structure)
(x) (CH.sub.3)
(CH.sub.3)
(CH.sub.3)
(H) (CH.sub.3)
(CH.sub.3)
(CH.sub.3)
(CH.sub.3)
(CH.sub.3)
(CH.sub.3)
(n, m) (3, 10)
(3, 3)
(3, 10)
(2, 70)
(4, 30)
(3, 0)
(3, 20)
(1, 8)
(5,
(3, 75)
Monomer B
Methyl methacrylate 120 169.2
45 85 58 72 120 150 87
Ethyl acrylate 10.8
Methacrylic acid 2
Butyl acrylate 5
Styrene 10
Butyl methacrylate 12 30
Radical polymerization initiator
Azobisisobutyronitrile
1.2 3.6 5 0.6 1.2 3.6
Benzoyl peroxide 3 15 0.6 4
Cooking Solvent b
Butyl acetate 40 60 20 60
Xylene 20 40
Ethylene glycol monoethyl ether 20
Polymerization Catalyst b
Azobisisobutyronitrile
0.6 1.8 0.6 0.6 1.8
Benzoyl peroxide 1.5 0.2
Diluting Solvent
Toluene 80 130
Xylene 120 80 120
Butyl acetate 100 100
Methyl isobutyl ketone 30
Butanol 10
Methyl ethyl ketone 35
Reaction Temperature (.degree.C.)
100 115 130 110 120 140 80 105 110 120
Appearance of Polymer Solution
clear
clear
clear
translucent
clear
clear
clear
turbid
clear
turbid
Viscosity of Polymer Solution
U H A P K A.sub.3
Z W K F
Molecular Weight of Polymer (.times. 10.sup.3)
89 54 9 43 27 1 150 72 65 32
__________________________________________________________________________
Note (*1):
##STR3##
EXAMPLES 1 TO 43
Forty-three samples of antifouling coating were prepared by dispersing the
copolymer solutions I to VII with a homomixer (2,000 rpm) in accordance
with the formulations shown in Tables 2 and 3 (the figures in the tables
are percents by weight). Paraffin wax 120P, paraffin wax 155P,
microcrystalline wax 170M, and petrolatum Nos. 1 and 4 listed in Tables 2
and 3 are petroleum waxes of the types specified in JIS K 2235; ISO VG 10
and ISO VG 100 are liquid paraffins of the types specified in JIS K 2231;
KF 96 L-10 and KF 96 H-50,000 are the trade names of Shin-Etsu Chemical
Co., Ltd. for silicone oils; Oil Blue.RTM.2N is the trade name of Orient
Chemical Industry Co., Ltd. for a dye; and Disparon .RTM.6900-20X and
Aerosil.RTM.300 are the trade names of Kusumoto Kasei K.K. and Nippon
Aerosil Co., Ltd, respectively, for antisagging agents.
COMPARATIVE EXAMPLES 1 TO 15
Fifteen samples of antifouling coating having the formulations shown in
Table 4 were prepared as in Examples 1 to 43 except that copolymer
solutions III, V, VII to X and KE 45 TS (the trade name of Shin-Etsu
Chemical Co., Ltd. for a 50 wt% toluene solution of a low temperature
curing oligomer-like silicone rubber) or an organotin copolymer solution
(Comparative Example 11) were employed.
The organotin copolymer solution used in Comparative Example 11 had been
prepared by copolymerizing 40 parts of methyl methacrylate, 20 parts of
octyl acrylate and 40 parts of tributyltin methacrylate; the copolymer had
a weight average molecular weight of 90,000 and was dissolved in xylene to
form a clear 50 wt% solution. The silicone oil designated as KF 96
H-60,000 in Table 4 was a product of Shinetsu Chemical Industry Co., Ltd.
This silicone oil (kinetic viscosity: 60,000 cSt at 25.degree. C.),
caproic acid (carbon number: 6), camellia oil (m.p.: -17.degree. C.) and
methyl caproate (carbon number: 6) were not within the category of the
slipping agents that are specified by the present invention for
incorporation in the claimed antifouling coating.
TABLE 2
Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Copolymer Solution (I) 45 90 56 64 Copolymer Solution
(II) 50 50 60 56 Copolymer Solution (III) 60 60
60 60 60 60 72 Copolymer Solution (IV) 50 Copolymer Solution (V)
55 Copolymer Solution (VI) 80 Copolymer Solution (VII) 40
63 38 Organic Amine Dodecylamine 1 Tetradecylamine
5 3 Hexadecylamine 3 2 Octadecylamine 10
Dihydrogenated tallow- alkylmethylamine 10 Tetradecyldimethy
lamine 10 Tallow alkylamine 27 3 Soybean
alkylamine 35 5 Petroleum Wax Petrolatum No. 1
5 3 10 Liquid Paraffin ISO VG 10 5 7 Silicone
Oil KF 96 L-10 (kinetic viscosity: 10 cSt at 25.degree. C.) 4
3 2 4 Fatty Acid Ester Tallow (m.p.: 45.degree. C.)
5 Palm oil (m.p.: 41.degree. C.) 5 Pigment
2 TiO.sub.2 5 2 Dye Oil Blue 2N 1
Antisagging Agent Disparon .RTM. 6900-20X 3 2 2 3 2 6 8 5 6 3 5 5
3 3 Aerosil .RTM. 300 1 2 1 1 1 2 Diluting Solvent Toluene 30
19 13 28 20 40 48 8 5 4 5 23 6 Xylene 22 20 10 20 3 8 15 22
5 10 10 27 4 15 10 Ethyl acetate 30 20 10 18 10 10 15 9 2 10
5 5 Methyl isobutyl ketone 2 5 4 Isopropyl alcohol
5 9 5 6 2 Total 100 100 100 100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100 100 100
TABLE 3
Example 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43
Copolymer Solution (I) 64 56 72 72 56 Copolymer
Solution (II) 40 65 54 56 Copolymer Solution (III) 42
54 48 54 54 Copolymer Solution (IV) 64 Copolymer
Solution (V) 56 40 64 Copolymer Solution (VI)
56 Copolymer Solution (VII) 60 72 56 Petroleum Wax
Paraffin wax 120P 9 7 Paraffin wax 155P 20 Microcryst
alline wax 170M 3 Petrolatum No. 1 8 3 Petrolatum
No. 4 20 Liquid Paraffin ISO VG 10 7 ISO VG 100 14
Silicone Oil KF 96 L-10 (kinetic viscosity: 10 cSt at 25.degree. C.
4 KF 96 H-50000 (kinetic viscosity: 5 .times.
10.sup.4 cSt at 25.degree. C.) 6 Fatty Acid Stearic acid (m.p.:
70.degree. C.) 7 Caprylic acid (m.p.: 17.degree. C.)
4 Fatty Acid Ester Tallow (m.p.: 45.degree. C.) 12
Lard (m.p.: 37.degree. C.) 9 12 Japan tallow (m.p.:
53.degree. C.) 20 Palm oil (m.p.: 41.degree. C.)
8 Spermaceti (m.p.: 48.degree. C.) 12 Bees wax (m.p.:
63.degree. C.) 3 Stearyl stearate (m.p.: 63.degree. C.)
8 Tripalmitin (m.p.: 58.degree. C.) 3
Pigment TiO.sub.2 5 Dye Oil Blue .RTM.2N
3 Antisagging Agent Disparon .RTM. 6900-20X 2 2 3 3 2 2
2 2 3 2 2 Aerosil .RTM. 300 1 1 1 1 1 1 1 Diluting Solvent
Toluene 27 10 23 6 5 20 16 33 10 22 20 7 Xylene 20 30 12 26 10
20 10 20 11 17 21 10 16 12 20 20 30 15 Ethyl acetate 10 20 5 5 5
10 20 7 10 10 20 10 10 5 Methyl isobutyl ketone 5 4 10 10
3 Isopropyl alcohol 2 3 3 Total 100 100 100 100 100
100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
TABLE 4
__________________________________________________________________________
Comparative Example
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
__________________________________________________________________________
Copolymer Solution (III) 42 42
Copolymer Solution (V) 42
Copolymer Solution (VII) 42
Copolymer Solution (VIII)
50 56
Copolymer Solution (IX)
50 60
Copolymer Solution (X) 50 42
Silicone Rubber
KE 45 TS 50 50 50 50
Solution of Organotin Copolymer 40
Petroleum Wax
Petrolatum No. 1 10
Petrolatum No. 4 12
Liquid Paraffin
ISO VG 10 10
Silicone Oil
KF 96 L-10 (kinetic viscosity:
10 cSt at 25.degree. C.) 10
KF 96 H-60000 (kinetic viscosity:
6 .times. 10.sup.4 cSt at 25.degree. C.) 9
Fatty Acid
Caproic acid 9
Fatty Acid Ester
Palm oil (m.p.: 41.degree. C.)
20
Camellia oil (m.p.: -17.degree. C.) 9
Tripalmitin (m.p.: 58.degree. C.)
9
Methyl caproate
Pigment
TiO.sub.2 5
Cuprous oxide 40
Antisagging Agent
Disparon .RTM. 6900-20X
3 3 3 2 3 2 2 2 2
Aerosil .RTM. 300 1
Diluting Solvent
Toluene 47 47 47 9 50 40 40 40 20 20 20 20
Xylene 21 18 20 12 22 15 22 22
Ethyl acetate 10 20 5 5 5 5
Methyl isobutyl ketone 5
Isopropyl alcohol 2
Total 100
100
100
100
100
100 100
100
100
100
100
100
100
100
100
__________________________________________________________________________
The performance of the samples of antifouling coating prepared in Examples
1 to 43 and Comparative Examples 1 to 15 was evaluated by a physical
performance test, the measurement of slip angles for the surface of the
film of coating formed from the individual samples and by an antifouling
performance test. Each of the tests and measurement thereof was conducted
by the procedures shown below. The results are shown in Tables 5 to 7.
Physical Performance Test
The storage stability, drying property and adhesion to a substrate were
evaluated for each sample by the following methods.
(A) Storage Stability
200 ml of each sample was put into a glass container (capacity: 250 ml)
which was closed with a cap. The container was stored in a humidified
thermostatic chamber (70.degree. C..times.75% RH) for two weeks. The
stability of the sample was determined in terms of any increase in its
viscosity and evaluated by the following criteria: o, the increase in
viscosity was less than 10% by the initial value; .DELTA., the increase
was from 10% to less than 100% of the initial value; and x, the increase
was at least 100% of the initial value.
(B) Drying Property
In accordance with the method specified in JIS K 5400.5.8, each of the
samples was coated onto a glass plate for a wet film thickness of 100
.mu.m with a film applicator and the drying property of the film was
evaluated by the following criteria: o, the tack-free drying time was less
than 1 hour; .DELTA., the tack-free drying time was from 1 hour to less
than 3 hours; and x, the tack-free drying time was at least 3 hours. Each
of the test pieces had been desiccated in a humidified thermostatic
chamber (20.degree. C..times.75% RH).
(C) Adhesion to Substrate
Evaluation of adhesion to a substrate was conducted in accordance with the
method of a cross cut adhesion test specified in JIS K 5400.6.15; each of
the samples was coated onto a polished steel panel (150.times.70.times.1
mm) for a wet film thickness of 100 .mu.m with a film applicator and dried
for 1 week in a humidified thermostatic chamber (20.degree. C..times.75%
RH); a 20 mm long crossed groove was cut through the film into the
substrate with a cutter knife; the so prepared test piece was set in an
Erichsen film tester and a steel ball was pressed against the center of
the back side of the test piece to produce a vertical deformation of 10
mm. The adhesion of the film to the substrate was evaluated in terms of
the length of peel from the substrate as measured from the center of the
cross cut. The criteria used were as follows: o, 0 mm; .DELTA., less than
5 mm; and x, 5 mm or more.
Measurement of Slip Angle
Test plates were prepared in the same manner as in the case of the drying
test (B) and the angle of slip on the surface of the film of coating
formed on each test plate was measured with a slip angle meter. As shown
in FIGS. 1(A) and (B), the slip angle meter was composed of a transparent
glass plate 1, a fastening device 2, a support rod 3 and a movable plate
4. The movable plate 4 was disposed on the glass plate 1 in such a manner
that it was fixed at one end A with the fastener 2 while the other end B
was movable upwardly along the rod 3.
The procedures of slip angle measurement were as follows. First, as shown
in FIG. 1(A), a test plate 5 was placed horizontally, with the film of
coating facing up, on the movable plate 4, and a given amount (0.2 ml) of
sterilized filtered seawater was injected with a syringe to deposit a
waterdrop 6 at a position whose distance (.gamma.) from the fastener 2
(i.e., one end A of the movable plate 4) was 185 mm. Then, as shown in
FIG. 1(B), the other end B of the movable plate 4 was moved upwardly along
the rod 3 at a speed of 1 mm/sec. The angle of inclination, .alpha., of
the movable plate 4 at which the waterdrop 6 began to slide down the
inclined test plate 5 was measured and used as the slip angle of the
surface of the film of coating on the test plate.
All measurements were conducted in a humidified thermostatic chamber
(25.degree. C..times.75% RH) and three measurements with each test plate
were averaged to calculate the slip angle for that plate.
Antifouling Performance Test
Sand blasted steel panels (100.times.200.times.1 mm) were coated with a
coal tar-vinyl based anticorrosive paint. Both surfaces of each panel were
sprayed with two layers of a coating so as to provide a dry film thickness
of 120 .mu.m on each side.
The so prepared test panels were immersed in seawater at Yura Bay, Sumoto,
Hyogo, Japan for 36 months, during which period the increase in the area
of the test panel that was covered by the growth of fouling marine
organisms (% attachment of fouling organisms) was measured at regular
intervals.
TABLE 5
__________________________________________________________________________
Example
1 2 3 4 5 6 7 8 9 10
11
12
13
14
15
16
17
18
19
20
21
__________________________________________________________________________
Storage stability
o o o o o o o o o o o o o o o o o o o o o
Drying property
o o o o o o o o o o o o o o o o o o o
o o
Adhesion to substrate
o o o o o o o o o o o o o o o o o o o
o o
Surface slip angle (degrees)
8.3
8.5
9.1
8.8
| | |
