COPOLYMER OF TRIISOPROPYLSILYL (METH)ACRYLATE WITH (METH)ACRYLIC ACID DERIVATIVE AND MAKING METHOD

Abstract

A copolymer of triisopropylsilyl (meth)acrylate with a (meth)acrylic acid derivative having a Mn of 6,000-100,000 and a Mw/Mn of up to 2.0 is provided. A paint composition comprising the copolymer and a relatively small amount of an organic solvent has a low viscosity.

Claims

1. A copolymer of monomers containing triisopropylsilyl (meth)acrylate having the general formula (1) and a (meth)acrylic acid derivative, the copolymer having a number average molecular weight of 6,000 to 100,000 and a polydispersity index (Mw/Mn) of up to 2.0, ##STR00015## wherein R.sup.1 is hydrogen or methyl.

2. The copolymer of claim 1 wherein the (meth)acrylic acid derivative has the general formula (2): ##STR00016## wherein R.sup.2 is hydrogen or methyl and R.sup.3 is a C.sub.1-C.sub.20 alkoxy group, a C.sub.6-C.sub.20 aryloxy group, a C.sub.1-C.sub.20 monovalent hydrocarbon group which may contain at least one divalent moiety selected from O, S and NR wherein R is hydrogen or a C.sub.1-C.sub.20 monovalent hydrocarbon group, with the proviso that heteroatoms such as oxygen, sulfur and nitrogen do not adjoin, and which may be substituted with silyl, carbonyl or halogen, an amino group, a siloxy group (exclusive of triisopropylsiloxy), a halogen atom or a hydroxyl group.

3. The copolymer of claim 1, comprising repeating units having the general formula (3): ##STR00017## wherein R.sup.1 to R.sup.3 are as defined above and a and b are numbers in the range: 0.2a0.8, 0.2b0.8, and a+b=1.

4. The copolymer of claim 1, comprising repeating units having the general formula (4): ##STR00018## wherein R.sup.1 to R.sup.3 are as defined above, R.sup.4 is hydrogen or methyl, a, b and c are numbers in the range: 0.2a0.8, 0.2b0.8, 0.2c0.8, and a+b+c=1, and R.sup.5 is a group having the general formula (5) or (6): ##STR00019## wherein R.sup.6 is a C.sub.1-C.sub.20 divalent hydrocarbon group which may contain O, with the proviso that oxygen atoms do not adjoin, R.sup.7 is hydrogen or a C.sub.1-C.sub.20 monovalent hydrocarbon group, n is an integer of 1 to 15, R.sup.8 and R.sup.9 each are a C.sub.1-C.sub.20 divalent hydrocarbon group, R.sup.10 is hydrogen or a C.sub.1-C.sub.20 monovalent hydrocarbon group, and m is an integer of 1 to 15.

5. A composition comprising the copolymer of claim 1 and an organic solvent.

6. The composition of claim 5 wherein the organic solvent is an aromatic hydrocarbon solvent.

7. The composition of claim 5 for use as antifouling paint.

8. A method for preparing the copolymer of claim 1, comprising the step of effecting group-transfer polymerization of monomers containing triisopropylsilyl (meth)acrylate having the formula (1) defined above and a (meth)acrylic acid derivative in the presence of a catalyst using a silylketene acetal having the general formula (7) as an initiator, ##STR00020## wherein R.sup.11 is a C.sub.1-C.sub.10 monovalent hydrocarbon group or a substituent: SiR.sup.12R.sup.13R.sup.14, R.sup.12 to R.sup.14 each are a C.sub.1-C.sub.10 monovalent hydrocarbon group, R.sup.15 and R.sup.16 each are hydrogen or a C.sub.1-C.sub.10 monovalent hydrocarbon group.

9. A method for preparing the copolymer of claim 1, comprising the step of effecting atomic transfer radical polymerization of monomers containing triisopropylsilyl (meth)acrylate having the formula (1) defined above and a (meth)acrylic acid derivative in the presence of a heavy metal salt and a ligand using a halogen compound having the general formula (8) as an initiator, ##STR00021## wherein R.sup.17 to R.sup.19 each are a halogen atom or C.sub.1-C.sub.10 monovalent hydrocarbon group, any one of R.sup.17 to R.sup.19 being halogen, R.sup.20 is a C.sub.1-C.sub.20 monovalent hydrocarbon group which may contain oxygen, sulfur or halogen.

10. The method of claim 9 wherein the heavy metal salt is a heavy metal halide.

11. The method of claim 9 wherein the ligand is an amine ligand.

12. A method for preparing the copolymer of claim 1, comprising the step of effecting reversible addition-fragmentation chain-transfer polymerization of monomers containing triisopropylsilyl (meth)acrylate having the formula (1) defined above and a (meth)acrylic acid derivative in the presence of a sulfur-containing compound using a radical compound as an initiator.

13. The method of claim 12 wherein the radical compound is an azo compound or organic peroxide.

14. The method of claim 12 wherein the sulfur-containing compound is a compound having trithiocarbonate, dithioester, thioamide, thiocarbamate or dithiocarbamate as a polymerization initiator group.

Description

DESCRIPTION OF PREFERRED EMBODIMENTS

[0032] As used herein, the notation (Cn-Cm) means a group containing from n to m carbon atoms per group. The term polydispersity (index) is a molecular weight distribution and given as Mw/Mn wherein Mw and Mn are weight and number average molecular weights, respectively.

[0033] The invention provides a copolymer of monomers containing triisopropylsilyl (meth)acrylate having the general formula (1) and a (meth)acrylic acid derivative, having a number average molecular weight (Mn) of 6,000 to 100,000 and a polydispersity index (Mw/Mn) of up to 2.0. The copolymer may be a random or block copolymer of triisopropylsilyl (meth)acrylate with (meth)acrylic acid derivative.

##STR00008##

[0034] In formula (1), R.sup.1 is hydrogen or methyl. That is, formula (1) represents triisopropylsilyl acrylate or triisopropylsilyl methacrylate, which may be used alone or in admixture.

[0035] The (meth)acrylic acid derivative has the general formula (2).

##STR00009##

[0036] In formula (2), R.sup.2 is hydrogen or methyl. R.sup.3 is an alkoxy group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms; an aryloxy group of 6 to 20 carbon atoms, preferably 6 to 16 carbon atoms, and more preferably 6 to 12 carbon atoms; a monovalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms, which may contain at least one divalent moiety selected from O, S, and NR (wherein R is hydrogen or a monovalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms), with the proviso that heteroatoms such as oxygen, sulfur and nitrogen do not adjoin each other, and which may be substituted with silyl, carbonyl or halogen; an amino group; a siloxy group (exclusive of triisopropylsiloxy); a halogen atom; or a hydroxyl group. It is noted that the alkoxy group and the hydrocarbon moiety in the monovalent hydrocarbon group may be linear, branched or cyclic.

[0037] Suitable groups R.sup.3 include linear alkoxy groups such as methoxy, ethoxy, propoxy, n-butoxy, n-pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, dodecyloxy, octadecyloxy, vinyloxy, and allyloxy; branched alkoxy groups such as isopropoxy, isobutoxy, tert-butoxy, isopentyloxy, sec-pentyloxy, tert-pentyloxy, neopentyloxy, 1-methylpentyloxy, isooctyloxy, and isodecyloxy; cyclic alkoxy groups such as cyclohexyloxy, 4-tert-butylcyclohexyloxy, and cyclodecyloxy; aryloxy groups such as phenoxy, benzyloxy, p-methylphenoxy, naphthoxy, isobornyloxy, glycidyloxy, 2-ethyl-2-adamantyloxy, and 3-hydroxy-1-adamantyloxy; monovalent hydrocarbon groups containing O such as 2-ethylhexyloxy, methoxymethyloxy, ethoxymethyloxy, 2-methoxyethyloxy, 3-methoxypropyloxy, 4-methoxybutyloxy, 2-ethoxyethyloxy, 3-ethoxypropyloxy, 4-ethoxybutyloxy, 5-methoxy-3-oxa-pentyloxy, 8-methoxy-3,6-dioxaoctyloxy, 2-hydroxyethoxy, 3-hydroxypropoxy, 4-hydroxybutoxy, 5-hydroxypentyloxy, 6-hydroxyhexyloxy, and tetrahydrofurfuryloxy; monovalent hydrocarbon groups containing S such as methylthio and ethylthio; monovalent hydrocarbon groups containing NR such as N-(methoxymethyl)methylamino, N-(2-methoxyethyl)methylamino, N-(dimethylaminomethyl)methylamino, and N-(2-dimethylaminoethyl)methylamino; monovalent hydrocarbon groups containing NR and O such as dimethylaminomethyloxy, 2-dimethylaminoethyloxy, 2-diethylaminoethyloxy, 2-ethylmethylaminoethyloxy, tert-butylaminoethyloxy, 2,2,6,6-tetramethyl-4-piperidyloxy, and N-succinimidyloxy; monovalent hydrocarbon groups in which one or more or even all hydrogen atoms are substituted by silyl, such as 3-[diethoxy(methyl)silyl]propyloxy and 3-(trimethylsilyl)propyloxy; monovalent hydrocarbon groups in which some or all hydrogen atoms are substituted by carbonyl, such as 2-carboxyethyloxy, 2-methoxycarbonylethyloxy, 3-carboxypropyloxy, 3-methoxycarbonylpropyloxy, and 3-methoxy-2-carbonylpropyloxy; monovalent hydrocarbon groups in which one or more or even all hydrogen atoms are substituted by halogen, such as 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyloxy, 1,1,1,3,3,3-hexafluoroisopropoxy, 2,2,2-trifluoroethoxy, 2,2,3,3-tetrafluoropropoxy, 1H,1H,5H-octafluoropentyloxy, 1H,1H,2H,2H-nonafluorohexyloxy, 2,2,3,3,3-pentafluoropropoxy, and 1H,1H,2H,2H-tridecafluoro-n-octyloxy; amino groups, e.g., dialkylamino, alkylamino and arylamino groups such as dimethylamino, diethylamino, n-propylamino, tert-butylamino, 3-(dimethylamino)propylamino, dibutylamino, methylamino, and phenylamino; siloxy groups, e.g., trialkylsiloxy (exclusive of triisopropylsiloxy), dialkylarylsiloxy and alkyldiarylsiloxy groups such as trimethylsiloxy, trimethoxysiloxy, triethylsiloxy, tri-n-propylsiloxy, tri-n-butylsiloxy, phenyldimethylsiloxy, diphenylmethylsiloxy, methyldiethylsiloxy, ethyldimethylsiloxy, and tert-butyldimethylsiloxy; halogen atoms such as fluorine, chlorine, bromine, and iodine; and a hydroxyl group.

[0038] Examples of R in the monovalent hydrocarbon group containing NR include saturated hydrocarbon groups, typically linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl, branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-pentyl, 3-pentyl, and tert-pentyl, and cyclic alkyl groups such as cyclopropyl, cyclohexyl, cyclopentyl, and cyclooctyl; unsaturated hydrocarbon groups including alkenyl groups such as vinyl, allyl, 1-propenyl, 1-methylpropenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and octadecenyl and alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl, tolyl, xylyl, mesityl, naphthyl, and biphenyl; and aralkyl groups such as benzyl, phenethyl, phenylpropyl, and phenylbutyl.

[0039] Examples of the (meth)acrylic acid derivative include (meth)acrylic acid, (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2,3,4-trimethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodedyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, vinyl (meth)acrylate, allyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, cyclodecyl (meth)acrylate, dicyclopentanyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, p-methylphenyl (meth)acrylate, naphthyl (meth)acrylate, isobornyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dimethylaminomethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-ethylmethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate, 2,2,6,6-tetramethyl-4-piperidine (meth)acrylate, N-succinimidyl (meth)acrylate, trimethylsilyl (meth)acrylate, trimethoxysilyl (meth)acrylate, triethoxysilyl (meth)acrylate, triethylsilyl (meth)acrylate, tri-n-butylsilyl (meth)acrylate, trimethylsilyl (meth)acrylate, triethylsilyl (meth)acrylate, tripropylsilyl (meth)acrylate, tri-n-butylsilyl (meth)acrylate, dimethylphenylsilyl (meth)acrylate, methyldiphenylsilyl (meth)acrylate, triphenylsilyl (meth)acrylate, diethylmethylsilyl (meth)acrylate, ethyldimethylsilyl (meth)acrylate, tert-butyldimethylsilyl (meth)acrylate, 3-[diethoxy(methyl)silyl]propyl (meth)acrylate, 3-(trimethylsilyl)propyl (meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl (meth)acrylate, 1,1,1,3,3,3-hexafluoroisopropyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-nonafluorohexyl (meth)acrylate, 2,2,3,3,3-pentafluoropropyl (meth)acrylate, and 1H,1H,2H,2H-tridecafluoro-n-octyl (meth)acrylate; (meth)acrylic amides such as (meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N-[3-(dimethylamino)-propyl](meth)acrylamide, N-phenyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-(methoxymethyl)methyl(meth)acrylamide, N-(2-methoxyethyl)methyl(meth)acrylamide, N-(dimethylaminomethyl)methyl(meth)-acrylamide, and N-(2-dimethylaminoethyl)methyl(meth)acrylamide; S-methyl thiomethacrylate, S-thioethyl thio(meth)acrylate, (meth)acryloyl chloride, and (meth)acryloyl bromide, which are compounds corresponding to repeating unit (b) in the general formulae (3) and (4).

[0040] Examples of the (meth)acrylic acid derivative also include dicyclopentanyloxyethyl (meth)acrylate, glycidyl (meth)acrylate, 3-hydroxy-1-adamantyl (meth)acrylate, methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 5-methoxy-3-oxapentyl (meth)acrylate, 8-methoxy-3,6-dioxaoctyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, poly(ethylene glycol) (meth)acrylate, poly(propylene glycol) (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate, which are compounds corresponding to repeating unit (c) in the general formula (4).

[0041] The copolymer obtained from the above monomers contains repeating units having the general formula (3).

##STR00010##

[0042] Herein R.sup.1 to R.sup.3 are as defined above. From the aspects of stable coating solubility and long-term antifouling performance of an antifouling paint composition, a and b are numbers in the range: 0.2a0.8, 0.2b0.8, preferably 0.2a0.75, 0.25b0.8, and more preferably 0.2a0.7, 0.3b0.8 and a+b=1.

[0043] More preferably, the copolymer contains repeating units having the general formula (4).

##STR00011##

[0044] Herein R.sup.4 is hydrogen or methyl, and R.sup.5 is a substituent group having the general formula (5) or (6). From the aspects of stable coating solubility and long-term antifouling performance of an antifouling paint composition, a, b and c are numbers in the range: 0.2a0.8, 0.2b0.8, 0.2c0.8, preferably 0.25a0.8, 0.2b0.75, 0.2c0.75, and more preferably 0.3a0.8, 0.2b0.7, 0.2c0.7 and a+b+c=1.

##STR00012##

[0045] In formula (5), R.sup.6 is a divalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms, which may contain O, with the proviso that oxygen atoms do not adjoin, R.sup.7 is hydrogen or a monovalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms, and n is an integer of 1 to 15.

[0046] In formula (6), R.sup.8 and R.sup.9 each are a divalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms, R.sup.10 is hydrogen or a monovalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, and more preferably 1 to 12 carbon atoms, and m is an integer of 1 to 15. It is noted that the hydrocarbon moiety in the hydrocarbon group may be linear, branched or cyclic.

[0047] Examples of the monovalent hydrocarbon groups R.sup.7 and R.sup.10 include saturated hydrocarbon groups including linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl, branched alkyl groups isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-pentyl, 3-pentyl, and tert-pentyl, and cyclic alkyl groups such as cyclopropyl, cyclohexyl, cyclopentyl, and cyclooctyl; unsaturated hydrocarbon groups including alkenyl groups such as vinyl, allyl, 1-propenyl, 1-methylpropenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonyl, decenyl, undecenyl, and octadecenyl and alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl, tolyl, xylyl, mesityl, naphthyl, and biphenyl; and aralkyl groups such as benzyl, phenethyl, phenylpropyl, and phenylbutyl.

[0048] Examples of the divalent hydrocarbon groups R.sup.6, R.sup.8 and R.sup.9 include C.sub.1-C.sub.20 alkylene groups such as methylene, ethylene, trimethylene, propylene, tetramethylene, and pentamethylene.

[0049] Examples of the substituent group having the formula (5) include hydroxyalkyl groups such as hydroxymethyl, 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, and 6-hydroxyhexyl; alkoxyalkyl groups such as methoxymethyl, ethoxymethyl, 2-methoxyethyl, 3-methoxypropyl, 4-methoxybutyl, 2-ethoxyethyl, 3-ethoxypropyl, and 4-ethoxybutyl; and groups wherein R.sup.6 contains an ether bond, such as 5-methoxy-3-oxa-pentyl, 8-methoxy-3,6-dioxaoctyl, 11-methoxy-3,6,9-trioxaundecyl, 7-methoxy-4-oxaheptyl, 9-methoxy-5-oxanonyl, 5-ethoxy-3-oxapentyl, 8-ethoxy-3,6-dioxaoctyl, and 9-ethoxy-5-oxanonyl.

[0050] Examples of the substituent group having the formula (6) include carbonyl-containing groups such as 2-(3-methoxypropyl)carbonyloxyethyl, 2-(4-methoxybutyl)carbonyloxyethyl, 2-(5-methoxypentyl)carbonyloxyethyl, 3-(3-methoxypropyl)carbonyloxypropyl, 3-(4-methoxybutyl)carbonyloxypropyl, 3-(5-methoxypentyl)carbonyloxypropyl, 4-(3-methoxypropyl)carbonyloxybutyl, 4-(4-methoxybutyl)carbonyloxybutyl, 4-(5-methoxypentyl)carbonyloxybutyl, 2-(3-hydroxypropyl)carbonyloxyethyl, 2-(4-hydroxybutyl)carbonyloxyethyl, 2-(5-hydroxypentyl)carbonyloxyethyl, 3-(3-hydroxypropyl)carbonyloxypropyl, 3-(4-hydroxybutyl)carbonyloxypropyl, 3-(5-hydroxypentyl)carbonyloxypropyl, 4-(3-hydroxypropyl)carbonyloxybutyl, 4-(4-hydroxybutyl)carbonyloxybutyl, and 4-(5-hydroxypentyl)carbonyloxybutyl.

[0051] Copolymerization of components having these substituent groups enables to hydrophilize the surface of a coating as applied and adjust the self-polishing ability.

[0052] The copolymer should have a number average molecular weight (Mn) of 6,000 to 100,000. With Mn in the range, a coating does not become brittle and the hydrolysis rate thereof is adequately suppressed. Mn is preferably 7,000 to 70,000, more preferably 9,000 to 50,000. If Mn is less than 6,000, the paint composition may have poor film-forming ability.

[0053] Also the copolymer should have a polydispersity (Mw/Mn) of up to 2.0 from the aspect of eliminating the influences of high and low molecular weight fractions. Preferably, Mw/Mn is up to 1.8, more preferably up to 1.6. If Mw/Mn of the copolymer exceeds 2.0, a high molecular weight fraction may act as a flocculant to increase the viscosity of the copolymer. If a low molecular weight fraction is included, it may detract from the film-forming ability of the paint. The lower limit of polydispersity is preferably 1.0 though not critical.

[0054] The Mn and Mw/Mn are determined by gel permeation chromatography (GPC) versus polystyrene standards under the following GPC conditions.

[0055] GPC Conditions [0056] Analyzer: HLC-8220GPC (Tosoh Co., Ltd.) [0057] Column: KF-402.5HQ (4.6 mm250 mm)+KF-404HQ (4.6 mm250 mm) (Shodex) [0058] Eluent: tetrahydrofuran (THF) [0059] Flow rate: 0.35 mL/min [0060] Detector: RI [0061] Column oven temperature: 40 C. [0062] Standards: polystyrene

[0063] Now the method for preparing the copolymer is described. The copolymer is obtained from polymerization of triisopropylsilyl (meth)acrylate of formula (1), a (meth)acrylic acid derivative, and an initiator in the presence of a catalyst.

[0064] The polymerization technique which is preferred from the aspect of a narrow polydispersity is living polymerization. Examples of the living polymerization include well-known living anion polymerization, living radical polymerization, and living cation polymerization. Inter alia, group-transfer polymerization (GTP) which is one type of living anion polymerization, atomic transfer radical polymerization (ATRP) which is one type of living radical polymerization, and reversible addition-fragmentation chain-transfer polymerization (RAFT) are especially preferred because a degree of monomer conversion is relatively high and a (meth)acrylate polymer having a narrow polydispersity can be produced.

[0065] First, the group-transfer polymerization (GTP) is described. The GTP is a technique for polymerizing (meth)acrylates in the presence of a catalyst using a silylketene acetal having the general formula (7) as an initiator. Specifically, any two of the monomer, catalyst and initiator are mixed prior to reaction. When the remaining one is added thereto, polymerization starts. The order of addition is not critical. Polymerization starts even when they are added in any order.

[0066] In copolymerization using two or more monomers, the reactor may be charged with all monomers at the start of the reaction. Alternatively, the reaction may start with one or two monomers. Once the reaction reaches the desired rate of polymerization, the remaining monomers may be added one after another to yield a block copolymer.

[0067] The silylketene acetal used as the initiator in the GTP technique has the general formula (7).

##STR00013##

[0068] Herein R.sup.11 is a monovalent hydrocarbon group of 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms, or a substituent group: SiR.sup.12R.sup.13R.sup.14, and R.sup.12 to R.sup.14 each are a monovalent hydrocarbon group of 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms. Examples of the substituent group: SiR.sup.12R.sup.13R.sup.14 include trimethylsilyl, triethylsilyl, triisopropylsilyl, triisobutylsilyl, triphenylsilyl, methyldiphenylsilyl, and dimethylphenylsilyl.

[0069] R.sup.15 and R.sup.16 each are a monovalent hydrocarbon group of 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms, or hydrogen.

[0070] Examples of these monovalent hydrocarbon groups are as illustrated above for R.sup.7 and R.sup.10 while their hydrocarbon moiety may be either linear, branched or cyclic.

[0071] Examples of the compound having formula (7) include methyl(trimethylsilyl)dimethylketene acetal, methyl(triethylsilyl)dimethylketene acetal, methyl(triisopropylsilyl)dimethylketene acetal, methyl(triisobutylsilyl)dimethylketene acetal, methyl(trimethylsilyl)diethylketene acetal, methyl(triphenylsilyl)dimethylketene acetal, methyl(methyldiphenylsilyl)dimethylketene acetal, methyl(dimethylphenylsilyl)dimethylketene acetal, bis(trimethylsilyl)dimethylketene acetal, bis(triethylsilyl)dimethylketene acetal, and bis(triisopropylsilyl)dimethylketene acetal. Inter alia, preference is given to methyl(trimethylsilyl)dimethylketene acetal, methyl(triethylsilyl)dimethylketene acetal, methyl(triisopropylsilyl)dimethylketene acetal, and bis(trimethylsilyl)dimethylketene acetal, from the standpoint of a high degree of conversion of monomers.

[0072] Suitable catalysts include onium compounds having a counter anion in the form of fluorine, azide, cyanide, carboxylate, or a salt with conjugated acid of the foregoing, metal fluorides, organophosphorus compounds, imidazolium salts, Lewis acids, and Bronsted acids. Of these, the onium compounds, Lewis acids and Bronsted acids are preferred because a copolymer with a narrow polydispersity is obtainable.

[0073] Examples include onium compounds such as tetrabutylammonium fluoride, tetrabutylammonium bifluoride, tetraethylammonium fluoride, tetramethylammonium fluoride, tetrabutylammonium acetate, tetrabutylammonium biacetate, tetrabutylammonium benzoate, tetrabutylammonium m-chlorobenzoate, tetrabutylammonium bibenzoate, tetrabutylammonium cyanide, tris(dimethylamino)sulfonium difluorotrimethylsilicate, tris(dimethylamino)sulfonium azide, tris(dimethylamino)sulfonium cyanide, and tris(dimethylamino)sulfonium bifluoride; metal fluorides such as potassium fluoride, sodium fluoride, and cesium fluoride; organophosphorus compounds such as phosphazene bases and tris(2,4,6-trimethoxyphenyl)phosphine; imidazolium salts such as 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene, 1,3-diisopropylimidazol-2-ylidene, and 1,3-di-tert-butylimidazol-2-ylidene; Lewis acids such as zinc chloride, zinc bromide, zinc iodide, diethylaluminum chloride, ethylaluminum chloride, dimethylaluminum chloride, diisobutylaluminum chloride, aluminum chloride, titanium(IV) chloride, tris(pentafluorophenyl)borane, triphenylmethyl tetrakis(pentafluorophenyl)borate, and N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide; and Bronsted acids such as bis(trifluoromethanesulfonyl)imide and 2,3,4,5,6-pentafluorophenylbis(trlfluoromethanesulfonyl)methane. Inter alia, preference is given to tetrabutylammonium compounds such as tetrabutylammonium bifluoride, tetrabutylammonium acetate, tetrabutylammonium biacetate, tetrabutylammonium benzoate, tetrabutylammonium m-chlorobenzoate, and tetrabutylammonium bibenzoate; tris(dimethylamino)sulfonium difluorotrimethylsilicate, N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide, and 2,3,4,5,6-pentafluorophenylbis(trifluoromethanesulfonyl)methane.

[0074] In the GTP, the molecular weight may be set depending on the amount of the initiator, silylketene acetal of formula (7) used.

[0075] Since the degree of polymerization corresponds to (moles of monomer)/(moles of initiator), the degree of polymerization multiplied by the molecular weight of the monomer and the conversion of the monomer gives the theoretical molecular weight. Thus, once the amounts of the monomer and the initiator used are properly selected, a copolymer having a certain molecular weight is obtainable.

[0076] The initiator is preferably used in an amount of 0.001 to 0.2 equivalent, more preferably 0.005 to 0.15 equivalent, and most preferably 0.01 to 0.1 equivalent based on the entire monomers used. As long as the initiator is used within the range, a desired copolymer is prepared in high yields.

[0077] The amount of the catalyst used is not particularly limited. From the aspects of reactivity and productivity, the catalyst is preferably used in an amount of 0.0001 to 1 mole, more preferably 0.0005 to 0.1 mole, and most preferably 0.001 to 0.05 mole per mole of the silylketene acetal of formula (7). The reaction temperature is preferably in a range of 100 C. to 200 C., more preferably 50 C. to 100 C., and even more preferably 0 C. to 50 C., though not limited thereto. The reaction time is preferably 0.1 to 30 hours, more preferably 0.5 to 20 hours, even more preferably 1 to 10 hours, though not limited thereto. Although the ambient atmosphere is acceptable, an inert gas atmosphere such as nitrogen or argon is preferred.

[0078] Although the polymerization reaction may take place in a solventless system, a solvent may be used. Suitable solvents include hydrocarbon solvents such as pentane, hexane, cyclohexane, heptane, isooctane, toluene, xylene, and mesitylene; aprotic polar solvents such as ethyl acetate, acetonitrile, propionitrile, N,N-dimethylformamide, and N-methylpyrrolidone; halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, and chlorobenzene; and ether solvents such as diethyl ether, tetrahydrofuran, dioxane, and dimethoxyethane. These solvents may be used alone or in admixture of two or more. Inter alia, toluene, xylene, mesitylene and tetrahydrofuran are preferred.

[0079] The copolymer obtained from GTP has a structure which contains the initiator's silyl group at one end of the copolymer after the completion of reaction. The silyl group at one end of the copolymer may be converted to a carboxylic acid or ester by addition of water or alcohol. Suitable alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol. The amount of the water or alcohol used is not particularly limited. The water or alcohol is preferably used in an amount of 0.1 to 10 moles, more preferably 0.5 to 7 moles, and most preferably 1 to 5 moles per mole of the initiator.

[0080] Next, the atomic transfer radical polymerization (ATRP) is described.

[0081] The ATRP is a technique for polymerizing (meth)acrylate in the presence of a heavy metal salt and a ligand using a halogen compound having the general formula (8) as an initiator. Specifically, the reactor is charged with the monomer, heavy metal salt, ligand and initiator prior to reaction. When the reactor is heated, polymerization starts.

[0082] In copolymerization using two or more monomers, the reactor may be charged with all monomers at the start of the reaction. Alternatively, the reaction may start with one or two monomers. Once the desired rate of polymerization is reached, the remaining monomers may be added one after another to yield a block copolymer.

##STR00014##

[0083] In formula (8), R.sup.17 to R.sup.19 each are a halogen atom or a monovalent hydrocarbon group of 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, with the proviso that any one of R.sup.17 to R.sup.19 is halogen. R.sup.20 is a monovalent hydrocarbon group of 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 12 carbon atoms, which may contain an oxygen, sulfur or halogen atom.

[0084] Examples of these monovalent hydrocarbon groups are as illustrated above for R.sup.7 and R.sup.10 while their hydrocarbon moiety may be either linear, branched or cyclic.

[0085] Examples of the halogen compound having formula (8) include tert-butyl 2-bromoisobutyrate, methyl 2-bromoisobutyrate, ethyl 2-bromoisobutyrate, 2 hydroxyethyl 2-bromoisobutyrate, ethylene bis(2-bromoisobutyrate), bis[2-(2-bromoisobutyloxy)ethyl]disulfide, 10-undecenyl 2-bromoisobutyrate, dodecyl 2-bromoisobutyrate, and octadecyl 2-bromoisobutyrate. Of these, methyl 2-bromoisobutyrate, ethyl 2-bromoisobutyrate, 10-undecenyl 2-bromoisobutyrate, and dodecyl 2-bromoisobutyrate are preferred from the standpoint of a high polymerization initiation ability.

[0086] The heavy metal salt is typically a heavy metal halide, examples of which include copper halides such as copper(I) bromide, copper(II) bromide, copper(I) chloride and copper(II) chloride; titanium halides such as titanium(II) chloride, titanium(III) chloride, titanium(IV) chloride and titanium(IV) bromide; iron halides such as iron(II) chloride, iron(III) chloride, iron(II) bromide, and iron(III) bromide; cobalt halides such as cobalt(II) chloride and cobalt(II) bromide; nickel halides such as nickel(II) chloride and nickel(II) bromide; molybdenum halides such as molybdenum(III) chloride and molybdenum(V) chloride; and ruthenium halides such as ruthenium(III) chloride. Of these, copper(I) bromide and copper(I) chloride are preferred from the standpoint of a high polymerization initiation ability.

[0087] The ligand is typically an amine ligand, examples of which include bidentate ligands such as 2,2-bipyridine, 4,4-dinonyl-2,2-bipyridine, N-(butyl)-2-pyridylmethanimine, and N-(octyl)-2-pyridylmethanimine; tridentate ligands such as N,N,NN,N-pentamethyldiethylenetriamine; and tetradentate ligands such as N-propyl-N,N-di(2-pyridylmethyl)amine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, hexamethyltris(2-aminoethyl)amine, N,N-bis(2-dimethylaminoethyl)-N,N-dimethylethylenediamine, tris(2-pyridylmethyl)amine, tris[2-(dimethylamino)ethyl]amine, 1,4,8,11-tetrazacyclotetradecane, 1,4,8,11-tetramethyl-1,4,8,11-tetrazacyclotetradecane, and N,N,N,N-tetrakis(2-pyridylmethyl)ethylenediamine. Of these, 2,2-bipyridine, 4,4-dinonyl-2,2-bipyridine, N,N,N,N,N-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, tris[2-(dimethylamino)ethyl]amine, and tris(2-pyridylmethyl)amine are preferred for increasing polymerization activity and obtaining a copolymer with a narrow polydispersity.

[0088] In the ATRP, the molecular weight may be set depending on the amount of the compound of formula (8) used as initiator. The initiator is preferably used in an amount of 0.001 to 0.2 equivalent, more preferably 0.003 to 0.15 equivalent, and most preferably 0.005 to 0.1 equivalent based on the entire monomers used. As long as the initiator is used within the range, a desired copolymer is prepared in high yields. The heavy metal salt is used in an amount of 0.001 to 0.2 equivalent, more preferably 0.003 to 0.15 equivalent, and most preferably 0.005 to 0.1 equivalent based on the entire monomers used although the amount is not limited thereto. The ligand is used in an amount of 0.001 to 0.2 equivalent, more preferably 0.003 to 0.15 equivalent, and most preferably 0.005 to 0.1 equivalent based on the entire monomers used although the amount is not limited thereto.

[0089] The reaction temperature is preferably in a range of 50 C. to 200 C., more preferably 0 C. to 150 C., and even more preferably 20 C. to 130 C., though not limited thereto. The reaction time is preferably 1 to 30 hours, more preferably 3 to 20 hours, even more preferably 5 to 10 hours, though not limited thereto. Although the ambient atmosphere is acceptable, an inert gas atmosphere such as nitrogen or argon is preferred.

[0090] Although the polymerization reaction may take place in a solventless system, a solvent may be used. Suitable solvents include hydrocarbon solvents such as pentane, hexane, cyclohexane, heptane, isooctane, toluene, xylene, and mesitylene; aprotic polar solvents such as ethyl acetate, acetonitrile, acetone, propionitrile, N,N-dimethylformamide, and N-methylpyrrolidone; protic polar solvents such as water, methanol, ethanol, and hexafluoro-2-propanol; halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, and chlorobenzene; and ether solvents such as diethyl ether, tetrahydrofuran, dioxane, and dimethoxyethane. These solvents may be used alone or in admixture of two or more. Inter alia, toluene, xylene, mesitylene, ethyl acetate, acetone, methanol, ethanol and N,N-dimethylformamide are preferred.

[0091] Next, the reversible addition-fragmentation chain-transfer polymerization (RAFT) is described.

[0092] The RAFT is a technique for polymerizing (meth)acrylate in the presence of a sulfur-containing compound as a chain-transfer agent (RAFT agent) using a radical compound as an initiator. Specifically, the reactor is charged with the monomer, radical initiator and RAFT agent prior to reaction. When the reactor is heated, polymerization starts.

[0093] In copolymerization using two or more monomers, the reactor may be charged with all monomers at the start of the reaction. Alternatively, the reaction may start with one or two monomers. Once the desired rate of polymerization is reached, the remaining monomers may be added one after another to yield a block copolymer.

[0094] Suitable radical compounds used as the initiator include azo compounds and organic peroxides. Suitable azo compounds include 1,1-azobis(cyclohexanecarbonitrile), 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(isobutyronitrile), 2,2-azobis(2-methylbutyronitrile), 2,2-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis(2-aminopropane)dihydrochloride, 2,2-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]-n-hydrate, 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2-azobis(N-butyl-2-methylpropionamide), dimethyl-2,2-azobis(isobutyrate), and 4,4-azobis(4-cyanovaleric acid). Of these, 1,1-azobis(cyclohexanecarbonitrile), 2,2-azobis(isobutyronitrile), 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2-aminopropane)dihydrochloride, and 4,4-azobis(4-cyanovaleric acid) are preferred for increasing the conversion rate of monomers.

[0095] Examples of the organic peroxide include di-tert-butyl peroxide, tert-butyl hydroperoxide, and benzoyl peroxide.

[0096] Examples of the sulfur-containing compound used as the chain-transfer agent (RAFT agent) include compounds having trithiocarbonate, dithioester, thioamide, thiocarbamate or dithiocarbamate as a polymerization initiator group. Of these, compounds having trithiocarbonate and dithioester are preferred for increasing the conversion rate of monomers and obtaining a copolymer with a narrow polydispersity.

[0097] Specific examples of the chain-transfer agent (RAFT agent) include 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-[(dodecylsulfanylthlocarbonyl)sulfanyl]pentanol, poly(ethylene glycol) methyl ether 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]-pentanoate (av. Mn=10,400), poly(ethylene glycol) methyl ether 4-cyano-4-pentanoate dodecyltrithiocarbonate (av. Mn=5,400), poly(ethylene glycol) methyl ether 4-cyano-4-pentanoate dodecyltrithiocarbonate (av. Mn=2,400), poly(ethylene glycol) methyl ether 41 cyano 4 pentanoate dodecyltrithiocarbonate (av. Mn=1,400), 2-phenyl-2-propylbenzodithioate, 1-(methoxycarbonyl)ethyl benzodithioate, 1-(methoxycarbonyl)ethyl benzodithioate, 2-cyano-2-propyl-4-cyanobenzodithioate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, 2-cyano-2-propyl benzodithioate, benzyl benzodithioate, ethyl 2-methyl-2-(phenylthiocarbonylthio)propionate, methyl 2-phenyl-2-(phenylcarbonothioyl)acetate, ethyl 2-(phenylcarbonothioylthio)propionate, 2-(dodecylthiocarbonothioylthio)propionic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropionate, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid N-hydroxysuccinimide ether, poly(ethylene glycol) methyl ether 2-methyl-2-propionic acid dodecyltrithiocarbonate (av. Mn=10,400), poly(ethylene glycol) bis[2-(dodecylthiocarbonothio)-2-methylpropionate] (av. Mn=10,800), 2-(dodecylthiocarbonothio)-2-methylpropionic acid 3-azido-1-propanol, 2-(dodecylthiocarbonothio)-2-methylpropionic acid pentafluorophenyl, poly(ethylene glycol) methyl ether 2-(dodecylthiocarbonothio)-2-methylpropionate (av. Mn=1,100), poly(ethylene glycol) methyl ether 2-(dodecylthiocarbonothio)-2-methylpropionate (av. Mn=5,000), poly(ethylene glycol) methyl ether 2-(dodecylthiocarbonothio)-2-methylpropionate (av. Mn=2,000), cyanomethyldodecyl trithiocarbonate, poly(ethylene glycol) bis[2-(dodecylthiocarbonothioylthio)-2-methylpropionate] (av. Mn=5,700), cyanomethyl(phenyl)carbamodithioate, benzyl-1H-pyrrole-1-carbodithioate, bis(thiobenzoyl)disulfide, and bis(dodecylsulfanylthiocarbonyl)disulfide.

[0098] In the RAFT, the molecular weight may be set depending on the amount of the RAFT agent used. The RAFT agent is preferably used in an amount of 0.001 to 0.2 equivalent, more preferably 0.003 to 0.15 equivalent, and most preferably 0.005 to 0.1 equivalent based on the entire monomers used. As long as the RAFT agent is used within the range, a desired copolymer is prepared in high yields.

[0099] From the standpoints of reactivity and productivity, the amount of the radical initiator used is preferably 0.0002 to 0.04 equivalent, more preferably 0.0006 to 0.03 equivalent, and most preferably 0.001 to 0.02 equivalent based on the entire monomers used, but not limited thereto.

[0100] The reaction temperature is preferably in a range of 50 C. to 200 C., more preferably 0 C. to 150 C., and even more preferably 20 C. to 130 C., though not limited thereto. The reaction time is preferably 1 to 30 hours, more preferably 3 to 20 hours, even more preferably 5 to 10 hours, though not limited thereto. Although the ambient atmosphere is acceptable, an inert gas atmosphere such as nitrogen or argon is preferred.

[0101] Although the polymerization reaction may take place in a solventless system, a solvent may be used. Suitable solvents include hydrocarbon solvents such as pentane, hexane, cyclohexane, heptane, isooctane, toluene, xylene, and mesitylene; aprotic polar solvents such as ethyl acetate, acetonitrile, acetone, propionitrile, N,N-dimethylformamide, and N-methylpyrrolidone; protic polar solvents such as water, methanol, ethanol, and hexafluoro-2-propanol; halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, and chlorobenzene; and ether solvents such as diethyl ether, tetrahydrofuran, dioxane, and dimethoxyethane. These solvents may be used alone or in admixture of two or more. Inter alia, toluene, xylene, mesitylene, ethyl acetate, tetrahydrofuran, methanol, ethanol and N,N-dimethylformamide are preferred.

[0102] A further embodiment of the invention is a composition comprising at least the copolymer defined above and an organic solvent. The composition may be used for resin modifiers, pigment dispersants, and the like as well as antifouling paints. In the composition, the content of the copolymer is 20 to 90 wt %, preferably 30 to 80 wt % based on the total weight of the composition.

[0103] Suitable organic solvents include aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as ethanol and isopropanol; and ester solvents such as ethyl acetate and butyl acetate. Inter alia, aromatic hydrocarbon solvents such as toluene and xylene are preferred from the aspects of productivity and manufacturing operation. The organic solvent is preferably used in an amount of 10 to 80 wt %, preferably 20 to 70 wt % based on the total weight of the composition. From the aspect of VOC reduction, it is desirable to decrease the amount of the organic solvent used. Since the copolymer has a low viscosity, the amount of organic solvent used can be reduced.

[0104] The copolymer is suited for antifouling paints, especially effective for antifouling paints to ship hulls and fishing nets. The antifouling paint may be prepared by adding an antifouling agent, a leaching control agent, and other additives to the copolymer and the organic solvent and mixing and dispersing them.

[0105] The antifouling agent is not particularly limited as long as it has biocidal and repellent effects to fouling marine organisms. Examples include copper(I) oxide, copper rhodanide, copper pyrithione, and zinc pyrithione.

[0106] The leaching control agent is not particularly limited as long as it enhances leaching of the antifouling agent from the antifouling coating and improves static antifouling properties. Examples include rosin derivatives such as gum rosins, wood rosins, hydrogenated rosins, and disproportionated rosins, aliphatic and cycloaliphatic monocarboxylic acids, and derivatives and metal salts of these monocarboxylic acids. Examples of the monocarboxylic acid compound include naphthenic acid, cycloalkenylcarboxylic acid, bicycloalkenylcarboxylic acid, versatic acid, trimethylisobutenylcyclohexenecarboxylic acid, stearic acid, hydroxystearic acid, salicylic acid, and metal salts thereof.

[0107] Further, other additives such as pigments, plasticizers, sag-control agents, anti-settling agents and dehydrating agents may be added to the antifouling paint composition, if necessary. The pigment is not particularly limited as long as it can adjust the color of the antifouling coating or impart the desired color. Any organic or inorganic pigments may be used. Suitable organic pigments include Carbon Black, Naphthol Red, and Phthalocyanine Blue. Suitable inorganic pigments include red iron oxide, talc, titanium oxide, silica, calcium carbonate, barium sulfate, mica, and clay. In order to improve the effect of preventing color unevenness of an antifouling coating, a pigment dispersant may be added. Typical of the organic pigment dispersant are aliphatic amines and organic acids. Typical of the inorganic pigment dispersant is ethylsilicate. The plasticizer is not particularly limited as long as it can improve the crack resistance of an antifouling coating. Suitable plasticizers include chlorinated paraffins, petroleum resins, ketone resins, tricresyl phosphate (TCP), polyvinyl ether, and dialkyl phthalates. The sag-control agent is not particularly limited as long as it can suppress sagging when the antifouling paint composition is applied to a structure. Suitable sag-control agents include amide wax, hydrogenated castor oil wax, and finely divided synthetic silica. The anti settling agent is not particularly limited as long as it can prevent precipitation in the antifouling paint composition during storage. Typical of the anti-settling agent is polyethylene oxide wax. The dehydrating agent is not particularly limited as long as it can prevent viscosity buildup during storage. A typical dehydrating agent is ethyl silicate.

[0108] The antifouling paint composition using the copolymer of the invention may be prepared by any well-known methods. For example, the antifouling paint composition may be prepared by adding the copolymer and other components to a milling vessel at a time or in any desired order and mixing them by a well-known stirring and mixing means. Suitable stirring and mixing means include a high speed disperser, sand grind mill, basket mill, and ball mill.

EXAMPLE

[0109] Examples of the invention are given below by way of illustration and not by way of limitation. The kinematic viscosity (in cSt) of a copolymer solution is measured at the liquid temperature of 25 C. by a Ubbelohde viscometer (Sibata Scientific Technology Ltd.).

Example 1

[0110] Synthesis of Copolymer A-1

[0111] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 5.0 g (0.0581 mol) of methyl acrylate, 5.0 g (0.0219 mol) of triisopropylsilyl acrylate, 190.9 mg (1.095 mmol) of methyl(trimethylsilyl)dimethylketene acetal, and 10.0 g of xylene. To the flask, 10.8 mg (0.024 mmol) of 2,3,4,5,6-pentafluorophenylbis(trifluoromethanesulfonyl)methane in a small amount of xylene was added at room temperature. The solution was stirred for 30 minutes. A small amount of methanol was then added to quench the reaction, obtaining a solution of copolymer A-1 in a substantially quantitative manner. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-1 are shown in Table 1.

Examples 2 and 3

[0112] Synthesis of Copolymers A-2 and A-3

[0113] A solution of copolymer A-2 or A-3 was obtained from polymerization reaction by the same method as in Example 1 aside from using the acrylate, triisopropylsilyl acrylate, polymerization initiator, catalyst, and organic solvent shown in Table 1. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymers A-2 and A-3 are shown in Table 1.

Example 4

[0114] Synthesis of Copolymer A-4

[0115] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 2.4 g (0.0581 mol) of methyl methacrylate, 2.4 g (0.0219 mol) of triisopropylsilyl methacrylate, 122.0 mg (0.70 mmol) of methyl(trimethylsilyl)dimethylketene acetal, and 5.0 g of tetrahydrofuran. To the flask, 6.8 mg (0.024 mmol) of tetrabutylammonium bibenzoate in a small amount of tetrahydrofuran was added at 65 C. The solution was stirred for 30 minutes. A small amount of methanol was then added to quench the reaction, obtaining a solution of a copolymer in a substantially quantitative manner. Tetrahydrofuran was distilled off from the reaction solution under vacuum. Xylene, 9.6 g, was added to the residue, obtaining a solution of copolymer A-4. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-4 are shown in Table 1.

Example 5

[0116] Synthesis of Copolymer A-5

[0117] A solution of copolymer A-5 was obtained from polymerization reaction by the same method as in Example 4 aside from using the methacrylate, triisopropylsilyl methacrylate, polymerization initiator, catalyst, and organic solvent shown in Table 1. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-5 are shown in Table 1.

Example 6

[0118] Synthesis of Copolymer A-6

[0119] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 5.0 g (0.050 mol) of methyl methacrylate, 5.0 g (0.021 mol) of triisopropylsilyl methacrylate, 195.1 mg (0.001 mol) of ethyl 2-bromoisobutyrate, 143.5 mg (0.001 mol) of copper(I) bromide, 230.4 mg (0.001 mmol) of 1,1,4,7,10,10-hexamethyltriethylenetetramine, and 10.0 g of xylene. The solution was heated and stirred at 85 C. for 18 hours, obtaining a solution of copolymer A-6. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-6 are shown in Table 2.

Example 7

[0120] Synthesis of Copolymer A-7

[0121] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 3.0 g (0.030 mol) of methyl methacrylate, 4.0 g (0.017 mol) of triisopropylsilyl methacrylate, 3.0 g (0.021 mol) of 2-methoxyethyl methacrylate, 195.1 mg (0.001 mol) of ethyl 2-bromoisobutyrate, 143.5 mg (0.001 mol) of copper(I) bromide, 230.4 mg (0.001 mmol) of 1,1,4,7,10,10-hexamethyltriethylenetetramine, and 10.0 g of xylene. The solution was heated and stirred at 80 C. for 7 hours, obtaining a solution of copolymer A-7. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-7 are shown in Table 2.

Example 8

[0122] Synthesis of Copolymer A-8

[0123] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 3.0 g (0.030 mol) of methyl methacrylate, 4.0 g (0.017 mol) of triisopropylsilyl methacrylate, 3.0 g (0.021 mol) of 2-methoxyethyl methacrylate, 403.7 mg (0.001 mol) of 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 32.8 mg (0.0002 mol) of azobisisobutyronitrile, and 10.0 g of xylene. The solution was heated and stirred at 80 C. for 10 hours, obtaining a solution of copolymer A-8. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-8 are shown in Table 2.

Example 9

[0124] Synthesis of Copolymer A-9

[0125] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 3.0 g (0.030 mol) of methyl methacrylate, 4.0 g (0.018 mol) of triisopropylsilyl acrylate, 3.0 g (0.021 mol) of 2-methoxyethyl methacrylate, 403.7 mg (0.001 mol) of 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 32.8 mg (0.0002 mol) of azobisisobutyronitrile, and 10.0 g of xylene. The solution was heated and stirred at 80 C. for 10 hours, obtaining a solution of copolymer A-9. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer A-9 are shown in Table 2.

Comparative Example 1

[0126] Synthesis of Copolymer B-1

[0127] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 60 g of xylene. With stirring at 855 C., a mixture of 30.0 g (0.348 mol) of methyl acrylate, 30.0 g (0.131 mol) of triisopropylsilyl acrylate and 0.6 g of 2,2-azobis(2-methylbutyronitrile) was added dropwise over 2.5 hours. The solution was stirred for one hour at the temperature. Thereafter, 0.6 g of 2,2-azobis(2-methylbutyronitrile) was added to the solution, which was stirred for a further 2 hours, obtaining a solution of copolymer B-1. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer B-1 are shown in Table 1.

Comparative Examples 2 and 3

[0128] Synthesis of Copolymers B-2 and B-3

[0129] A solution of copolymer B-2 or B-3 was obtained from polymerization reaction by the same method as in Comparative Example 1 aside from using the acrylate, triisopropylsilyl acrylate, polymerization initiator, and organic solvent shown in Table 1. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymers B-2 and B-3 are shown in Table 1.

Comparative Example 4

[0130] Synthesis of Copolymer B-4

[0131] A 100-ml four-neck round bottom flask equipped with a reflux condenser, thermometer, and stirrer was purged with nitrogen and charged with 6 g of xylene. With stirring at 855 C., a mixture of 3.0 g (0.0348 mol) of methyl methacrylate, 3.0 g (0.131 mol) of triisopropylsilyl methacrylate and 0.6 g of 2,2 azobis(2-methylbutyronitrile) was added dropwise over 2.5 hours. The solution was stirred for one hour at the temperature. Thereafter, 0.6 g of 2,2-azobis(2-methylbutyronitrile) was added to the solution, which was stirred for a further 2 hours. Xylene, 6 g, was added thereto, obtaining a solution of copolymer B-4. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer B-4 are shown in Table 1.

Comparative Example 5

[0132] Synthesis of Copolymer B-5

[0133] A solution of copolymer B-5 was obtained from polymerization reaction by the same method as in Comparative Example 4 aside from using the methacrylate, triisopropylsilyl methacrylate, polymerization initiator, and organic solvent shown in Table 1 and then adding the predetermined amount of xylene to the reaction solution. The kinematic viscosity, Mn, Mw, and Mw/Mn of copolymer B-5 are shown in Table 1.

TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 5 1 2 3 4 5 (Meth)acrylate Methyl acrylate 50 30 30 50 30 30 (wt %) 2-Methoxyethyl acrylate 20 10 20 10 Methyl methacrylate 50 30 50 30 2-Methoxyethyl 30 30 methacrylate Triisopropylsilyl Triisopropylsilyl acrylate 50 50 60 50 50 60 (meth)acrylate Triisopropylsilyl 50 40 50 40 (wt %) methacrylate Polymerization Methyl(trimethylsilyl)- 1.9 2.5 2.5 2.5 2.5 initiator dimethylketene acetal (wt %) 2,2-Azobis(2-methyl- 0.02 0.02 0.02 0.02 0.02 butyronitrile) Catalyst 2,3,4,5,6-Pentafuluoro- 0.11 0.12 0.12 (wt %) phenylbis(trifluoromethane- sulfonyl)methane tetrabutylammonium 0.14 0.14 bibenzoate Organic solvent Xylene 100 100 100 200 200 100 100 100 200 200 (wt %) Copolymer Kinematic viscosity (cSt) 40 18 29 30 40 71 58 112 49 95 solution Mn (10.sup.2) 100 90 120 110 120 90 80 82 120 100 Mw (10.sup.2) 115 108 135 135 140 340 184 380 320 320 Mw/Mn 1.15 1.20 1.13 1.23 1.17 3.78 2.30 4.63 2.67 3.20 Designation of copolymer A-1 A-2 A-3 A-4 A-5 B-1 B-2 B-3 B-4 B-5 in solution

TABLE-US-00002 TABLE 2 Example 6 7 8 9 (Meth)acrylate Methyl methacrylate 50 30 30 30 (wt %) 2-Methoxyethyl methacrylate 30 30 30 Triisopropylsilyl Triisopropylsilylmethacrylate 50 40 40 (meth)acrylate Triisopropylsilyl acrylate 40 (wt %) Radical initiator 2,2-Azobis(2-methylbutyronitrile) 0.3 0.3 (wt %) RAFT agent 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)- 4.0 4.0 (wt %) sulfanyl]pentanoic acid Heavy metal salt Copper(I) bromide 1.4 1.4 (wt %) ATRP initiator Ethyl 2-bromoisobutyrate 2.0 2.0 (wt %) Ligand 1,1,4,7,10,10-Hexamethyltriethylenetetramine 2.3 2.3 (wt %) Organic solvent Xylene 200 200 200 200 (wt %) Copolymer solution Kinematic viscosity (cSt) 18 42 29 39 Mn (10.sup.2) 49 81 77 75 Mw (10.sup.2) 67 120 92 99 Mw/Mn 1.37 1.40 1.19 1.33 Designation of copolymer in solution A-6 A-7 A-8 A-9

[0134] As seen from Table 1, copolymers A-1, A-2, and A-3 in Examples 1 to 3 have a lower kinematic viscosity than copolymers B-1, B-2, and B-3 in Comparative Examples 1 to 3.

[0135] Typically copolymers have a high kinematic viscosity. When such copolymers are used for paints, they must be diluted with organic solvents. Copolymers having a lower kinematic viscosity need a less amount of organic solvent for dilution.

[0136] As seen from Tables 1 and 2, copolymers A-4, A-5, A-6, A-7, A-8, and A-9 in Examples 4 to 9 also have a lower kinematic viscosity than copolymers B-4 and B-5 in Comparative Examples 4 and 5. It has been demonstrated that using the inventive copolymer, the amount of organic solvent needed for dilution is reduced.

[0137] Japanese Patent Application No. 2016-196079 is incorporated herein by reference.

[0138] Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.