Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-07-27
2002-05-28
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C523S122000, C523S177000, C106S015050, C106S017000
Reexamination Certificate
active
06395866
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyester resin for an antifouling paint and an antifouling paint containing the resin. More particularly, the present invention relates to a resin for an antifouling paint used for preventing fouling by aquatic fouling organisms, such as microorganisms, algae and the like, that attach to the surface under water of various structures, such as watercraft, marine structures, seawater conduits and the like, and various tools such as fish net and the like, and to an improved antifouling paint containing the resin and an antifouling agent.
BACKGROUND OF THE INVENTION
Aquatic fouling organisms such as acone barnacle, blue mussel, hydrozoan, serpula, moss animal, sea squit, sponge and the like; algae and cyanobacteria (e.g., laver, green laver, Ectocarpus, Ulothrix flacca, Cladophora spp., sea staghorn and the like); Bacillariophyceae; and aquatic fouling microorganisms such as bacteria that form slime (hereinafter these are also generally referred to as fouling organisms) attach to articles, equipments and structures left under water for a long period of time, such as the bottom of watercraft, submarine communication cables, transportation pipelines, observation buoy, buoy, oil fence, silt protector, bridge pier, cooling channel used for thermal and nuclear electric power generation, industrial cooling channel, buoy for tidal electric power generation, various hardware for marine development and marine work, fish net for aquaculture, fishing tools and the like. The above-mentioned articles, equipments and structures and the like suffer from various damages.
When a fouling organism attaches to watercraft, for example, the frictional resistance between the body of the watercraft and seawater increases to deaden the headway of the ship and to increase fuel consumption. In addition, the fouling organisms bring about an immense economic loss in the maintenance and service of watercraft, as evidenced by an economic loss resulting from the suspended service of watercraft, cleaning expenses and the like created by the fouled bottom of the ship and the like. In the case of the structures built in the sea, such as pier and the like, the film formed to enhance the durability is degraded or eroded due to the fouling organisms, resulting in a shortened service life of the structures. In the case of a structure such as buoy, the buoyancy of the structure decreases to result in immersion of the structure in water. In the case of cooling channels, such as condensers in power plants, heat exchangers in various plants and the like, various damages and losses are caused, such as increased resistance during water intake, lower heat exchange efficiency due to the attached fouling organisms, degraded performance of condenser and heat exchanger due to biological lumps that dropped from the water channel, and the like. Moreover, when fouling organisms attach to a fish net used for the aquaculture of fish and shellfish, the durability of the net itself may be impaired, and oxygen in water may run short because the fouling organisms spread on the net and prevent inflow and outflow of the seawater, which in turn results in suffocation and death of the fish and shellfish in aquaculture, as well as promoted growth of bacteria and the like, which can lead to a damage to fish and shellfish upon outgrowth of diseases among them.
As explained above, attaching of fouling organisms to the watercraft, structures and the like under water brings an extremely large industrial damage. For the prevention of the fouling organisms from attaching to the watercraft, structures and the like, an antifouling paint containing an antifouling agent and a hydrolyzable resin has been conventionally used. As the antifouling agent, there have been used heavy metal compounds, such as copper suboxide, copper thiocyanate and the like, carbamate compounds, such as tetramethyl thiuram disulfide and zinc dimethyldithiocarbamate, and the like. Examples of the hydrolyzable resin include TBTO pendant acrylic resin, silyl ester acrylic resin and the like. A film formed from such antifouling paint keeps exhibiting stable antifouling property for a long time because the surface of the film is gradually decomposed (chipped) due to hydrolysis of the hydrolyzable resin, and the active antifouling agent always appears on the surface of the film. However, possible pollution of the seawater by these antifouling agents and decomposed resins has been of concern in recent years.
Therefore, there is a demand for an antifouling paint which gives only a small burden on the marine environment, affords superior painting performance and superior properties of a film, and which permits fine hydrolysis (inclusive of biodegradation).
The present invention has been made in view of such demand, and aims at providing a resin for an antifouling paint capable of reducing contamination of the seawater, and an antifouling paint containing the resin.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an antifouling paint which hydrolyzes well (inclusive of biodegradation) and affords superior painting performance and superior properties of a film, the paint incorporating an aliphatic polyester resin that contains a metal in the main chain at a specific concentration and that has a specific acid value. As used in the specification, by the biodegradation is meant hydrolysis involving microorganisms and the like.
The polyester resin for an antifouling paint of the present invention characteristically contains a structural unit of the following formula (I)
wherein R
1
is or alkyl having 1 to 3 carbon atoms, R
2
is H or methyl and n is an integer of 0-4, in a proportion of not less than 90 mol %, contains a metal in the main chain at a concentration of 10-300 eq/10
6
g, and has an acid value of 20-1000 eq/10
6
g.
In a preferable embodiment of the above-mentioned polyester resin for an antifouling paint, not less than 80 mol % of the structural unit of the above-mentioned the formula (I) is a lactic acid residue.
In another preferable embodiment of the above-mentioned polyester resin for an antifouling paint, the molar ratio of the L-lactic acid residue and the D-lactic acid residue of the above-mentioned lactic acid residue (L-lactic acid residue/D-lactic acid residue) is within the range of from 1 to 9.
In yet another preferable embodiment of the above-mentioned polyester resin for an antifouling paint, the above-mentioned resin has a reduced viscosity (&eegr;
SP
/C) of 0.2-1.0 dl/g.
The present invention also provides an antifouling paint containing any of the above-mentioned polyester resins for an antifouling paint and an antifouling agent.
In a preferable embodiment, the above-mentioned antifouling agent is a natural antifouling agent.
In yet another preferable embodiment, the above-mentioned natural antifouling agent is selected from the compound group consisting of tannins, terpenes, vitamins, thiocyanates, isothiocyanates and gramine compounds.
DETAILED DESCRIPTION OF THE INVENTION
The polyester resin for an antifouling paint of the present invention contains a structural unit of the aforementioned formula (I) in a proportion of not less than 90 mol %, contains a metal in the main chain at a concentration of 10-300 eq/10
6
g, and has an acid value of 20-1000 eq/10
6
g.
With regard to the structural unit of the formula (I), the alkyl having 1 to 3 carbon atoms, which is represented by R
1
, is, for example, methyl, ethyl, n-propyl, isopropyl and the like.
Examples of the structural unit of the formula (I) include lactic acid residue, glycolic acid residue, 2-hydroxyisobutyric acid residue, 3-hydroxyisobutyric acid residue, 4-hydroxyvaleric acid residue and the like.
That is, the polyester resin for an antifouling paint of the present invention is an aliphatic polyester containing, as the main ingredient (not less than 90 mol %), at least one unit selected from the above-mentioned units. Examples thereof include poly(lactic acid), poly(glycolic acid), poly(2-hydroxyisobutyric acid
Akamine Kenichi
Hayashi Yoshitaka
Ito Takeshi
Mitsusada Suetsugu
Miyamoto Takashi
Leydig , Voit & Mayer, Ltd.
Toyo Boseki Kabushiki Kaisha
Yoon Tae H.
LandOfFree
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