WO2013062119A1

WO2013062119A1 - Curable composition

Info

Publication number: WO2013062119A1
Application number: PCT/JP2012/077816
Authority: WO
Inventors: Keiichi Akinaga; Akito Hayashi
Original assignee: Dow Corning Toray Co., Ltd.
Priority date: 2011-10-25
Filing date: 2012-10-22
Publication date: 2013-05-02
Also published as: JP2013091701A

Abstract

A curable composition in which a carbinol group-containing cyclic organopolysiloxane is compounded. Such composition shows improved hardness and/or scratch resistance of a cured product of a curable composition such as a curable coating or the like.

Description

DESCRIPTION

CURABLE COMPOSITION TECHNICAL FIELD

[0001] The present invention relates to a curable composition containing a carbinol

group-containing cyclic organopolysiloxane, and particularly relates to a coating-use curable composition such as a curable coating or the like.

BACKGROUND ART

[0002] Conventionally, compounding a linear carbinol-modified dimethylpolysiloxane in a coating is known. For example, Japanese Unexamined Patent Application Publication Nos.

2003-506519, H09-328652, H10-298290, and H02-64181 described compounding a

carbinol-modified dimethylpolysiloxane in a coating film in order to impart flexibility, followability, and the like.

[0003] Likewise, compounding a reticular carbinol-modified silicone resin in a coating is known. For example, Japanese Unexamined Patent Application Publication Nos. H10-87834,

H07-82522, H07-82525, 2009-531521 , 2009-531522, 2007-525604, 2007-528424, and

2007-528425 describe compounding a carbinol-modified silicone resin in a coating film for the purpose of imparting scratch resistance.

PRIOR ART DOCUMENTS

Patent Documents

[0004] Patent Document 1 : Japanese Unexamined Patent Application Publication No.

2003-506519

Patent Document 2: Japanese Unexamined Patent Application Publication No. H-09-328652 Patent Document 3: Japanese Unexamined Patent Application Publication No. H-10-298290 Patent Document 4: Japanese Unexamined Patent Application Publication No. H-02-64181 Patent Document 5: Japanese Unexamined Patent Application Publication No. H-10-87834 Patent Document 6: Japanese Unexamined Patent Application Publication No. H-07-82522 Patent Document 7: Japanese Unexamined Patent Application Publication No. H-07-82525 Patent Document 8: Japanese Unexamined Patent Application Publication No. 2009-53 521 Patent Document 9: Japanese Unexamined Patent Application Publication No. 2009-531522 Patent Document 10: Japanese Unexamined Patent Application Publication No. 2007-525604 Patent Document 11: Japanese Unexamined Patent Application Publication No. 2007-528424 Patent Document 12: Japanese Unexamined Patent Application Publication No. 2007-528425

SUMMARY OF INVENTION

[0005] However, when compounding a carbinol-modified dimethylpolysiloxane in a coating, hardness of the coating declines and there are cases where it is difficult to enhance scratch resistance.

[0006] On the other hand, when compounding a carbinol-modified silicone resin in a coating, it is possible to enhance the scratch resistance of the coating film, but there are cases where it is difficult to increase the hardness of the coating film. Additionally, silicone resins are typically solid at room temperature and, therefore, have poor handling. Therefore, it is necessary to dissolve the silicone resin in a solvent and use it as a solution. However, in some cases it is difficult to select a solvent having suitable solubility depending on the type of silicone resin used, and the coating may become contaminated by the solvent. As a result, compounding in aqueous coatings is difficult and, in some cases, there is a problem with dilution of the active component.

[0007] The present invention was created to resolve these problems with the existing technology. An object of the present invention is to provide an additive by which the hardness and scratch resistance of a cured product of a composition can be enhanced by compounding said additive in a curable composition such as a coating or the like and, moreover, by which excellent handling is obtained, and by which the use of a solvent will be unnecessary or the content of said solvent can be suppressed. Furthermore, another object of the present invention is to provide a curable composition whereby excellent hardness and scratch resistance of a cured product are obtained due to the compounding of the additive described above.

[0008] As a result of intensive investigation aimed at achieving the above objects, the present inventors arrived at the present invention. That is, the objects of the present invention are achieved by an additive for a curable composition containing a carbinol group-containing cyclic organopolysiloxane as an active component for enhancing hardness and/or scratch resistance of a cured product.

[0009] Kinetic viscosity at 25°C of the additive of the present invention is preferably from 0.1 to 10,000 mm²/s.

[0010] The carbinol group-containing cyclic organopolysiloxane is preferably a compound expressed by the following general formula (1):

[R¹R²Si0_2/2]_n[R¹ ₂Si0_2/2]_m (1)

In the formula, R¹ are each independently substituted or unsubstituted straight or branched monovalent hydrocarbon groups having from 1 to 20 carbons;

R² are each independently substituted or unsubstituted straight or branched monovalent hydrocarbon groups having from 1 to 20 carbons and at least one hydroxyl group;

"n" is an integer from 2 to 8;

"m" is an integer from 0 to 4;

n≥m; and 3<n+m≤8.

[0011] In the general formula (1), the "n" moiety is preferably an integer from 4 to 6.

[0012] In the general formula (1), the "m" moiety is preferably 0.

[0013] The monovalent hydrocarbon groups having at least one hydroxyl group can comprise ether bonds, thioether bonds, or imino bonds.

[0014] The carbinol group-containing cyclic organopolysiloxane is preferably obtained via a hydrosilylation reaction of a cyclic polyorgano hydrogensiloxane and an alcoholic hydroxyl group-containing compound having unsaturated bonds.

[0015] The alcoholic hydroxyl group-containing compound having unsaturated bonds can comprise ether bonds, thioether bonds, or imino bonds.

[0016] The alcoholic hydroxyl group may be protected.

[0017] Additionally, the objects of the present invention are achieved by a curable composition containing the additive described above. The curable composition of the present invention is preferably a coating-use curable composition.

[0018] The coating-use curable composition of the present invention can be suitably used as a curable coating, particularly as a urethane-based coating. Note that the present invention also relates to a cured coating film of the curable coating and an article comprising said cured coating film.

[0019] Furthermore, the present invention relates to a method for enhancing hardness and/or scratch resistance of a cured product of a curable composition, the method comprising compounding a carbinol group-containing cyclic organopolysiloxane in said curable composition.

The compounds described above can be used as the carbinol group-containing cyclic organopolysiloxane. The curable composition and the cured product are preferably the curable coating and the cured coating film described above, respectively.

[0020] The additive of the present invention can enhance the hardness and/or the scratch resistance of a cured product of a composition by compounding said additive in a curable composition such as a coating or the like. Moreover, with the additive of the present invention excellent handling can be obtained, and the use of a solvent can be made unnecessary or the content of said solvent can be reduced.

[0021] Moreover, by compounding the additive described above in the curable composition of the present invention, the hardness and/or the scratch resistance of the cured product can be made excellent and, particularly, both the hardness and the scratch resistance can be enhanced.

DESCRIPTION OF EMBODIMENTS

[0022] An additive for a curable composition of the present invention contains a carbinol group-containing cyclic organopolysiloxane as an active component for enhancing hardness and/or scratch resistance of a cured product of said curable composition. [0023] The additive of the present invention is preferably not a solid and has fluidity. Particularly, from the perspective of being effective as a reactive diluent of the curable composition, the additive of the present invention preferably has a kinetic viscosity at 25°C of 0.1 to 10,000 mm²/s, more preferably from 0.5 to 3,000 mm²/s, and even more preferably from 1 to 2,000 mm²/s. The kinetic viscosity can be measured via the method described in JIS-K-2283.

[0024] The carbinol group-containing cyclic organopolysiloxane is preferably a compound expressed by the following general formula (1):

[ ²Si0_2/2]_n [R¹ ₂Si0_2/2]_m (1)

In the formula, R¹ are each independently substituted or unsubstituted straight or branched monovalent hydrocarbon groups having from 1 to 20 carbons, preferably from 1 to 12 carbons, and more preferably from 1 to 8 carbons;

R² are each independently substituted or unsubstituted straight or branched monovalent hydrocarbon groups having at least one hydroxyl group and from 1 to 20 carbons, preferably from 1 to 12 carbons, and more preferably from 1 to 8 carbons;

"n" is an integer from 2 to 8, preferably from 4 to 8, and more preferably from 4 to 6;

"m" is an integer from 0 to 4 and preferably is 0;

n≥m; and

3≤n+m≤8 and preferably 4≤n+m≤6.

[0025] The substituted or unsubstituted straight or branched monovalent hydrocarbon groups (R¹ in the general formula (1)) are not particularly limited, and examples thereof include methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, and similar alkyl groups; cyclopentyl groups, cyclohexyl groups, and similar cycloalkyl groups; vinyl groups, allyl groups, butenyl groups, and similar alkenyl groups; phenyl groups, tolyl groups, and similar aryl groups; benzyl groups and similar aralkyl groups; and groups wherein the hydrogen atoms bonded to the carbon atoms of these groups are substituted at least partially by fluorine or a similar halogen atom, or an epoxy group, a glycidyl group, an acyl group, a carboxyl group, an amino group, a methacryl group, a mercapto group, or a similar organic group (however, excluding hydroxyl groups).

[0026] Particularly, the R¹ moieties are preferably monovalent hydrocarbon groups not having unsaturated aliphatic bonds or monovalent fluorinated hydrocarbon groups. Examples of the monovalent hydrocarbon groups not having unsaturated aliphatic bonds belonging to the R¹ moiety include methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, and similar alkyl groups; phenyl groups, tolyl groups, xylyl groups, and similar aryl groups; and aralkyl groups such as benzyl groups. Examples of the monovalent fluorinated hydrocarbon group include trifluoropropyl groups, pentafluoroethyl groups, and similar perfluoroalkyl groups. From an industrial perspective, the R¹ moieties are preferably methyl groups, ethyl groups, or phenyl groups, and more preferably from 90 mol to 100% of all the R¹ moieties are selected from methyl groups, ethyl groups, or phenyl groups.

[0027] The substituted or unsubstituted, straight or branched monovalent hydrocarbon groups having at least one hydroxyl group (R² in the general formula (1)) are also not particularly limited provided that they are a group in which at least one hydrogen atom on the hydrocarbon group is substituted with a hydroxyl group. Examples thereof include hydroxyalkyl groups

(hydroxymethyl groups, 2-hydroxyethyl groups, 3-hydroxypropyl groups, 2-hydroxypropyl groups, 4-hydroxybutyl groups, 3-hydroxybutyl groups, 2-hydroxybutyl groups, hydroxyoctyl groups, and the like) and hydroxyaryl groups (hydroxyphenyl groups, 2-methyl-4-hydroxyphenyl groups, and the like). In cases where the R² moieties are straight monovalent hydrocarbon groups, a hydroxyl group preferably exists on an end of the molecule.

[0028] The R² moieties can comprise ether bonds (-0-), thioether bonds (-S-), or imino bonds (-NR³-). The R³ moiety can be a hydrogen atom or the same monovalent hydrocarbon groups as the R¹ moieties. In cases where the R² moieties are straight monovalent hydrocarbon groups, the ether bonds, thioether bonds, or imino bonds may exist on the ends of the main chain or within the main chain of the R² moieties. Examples of the R² moieties having the ether bonds, the thioether bonds, or the imino bonds include -0-CH₂-OH, -0-(CH₂)₂-OH, -0-(CH₂)₃-OH, -0-(CH₂)₄-OH, -CH₂-0-CH₂-OH, -CH₂-0-(CH₂)₂-OH, -CH₂-0-(CH₂)₃-OH, -CH₂-0-(CH₂)₄-OH, -(CH₂)₂-0-CH₂-OH, -(CH₂)₂-0-(CH₂)₂-OH, -(CH₂)₂-0-(CH₂)₃-OH, -(CH₂)₂-0-(CH₂)₄-OH,

-(CH₂)₃-0-CH₂-OH, -(CH₂)₃-0-(CH₂)₂-OH, -(CH₂)₃-0-(CH₂)₃-OH, -(CH₂)₃-0-(CH₂)₄-OH,

-(CH₂)₄-0-CH₂-OH, -(CH₂)₄-0-(CH₂)₂-OH, -(CH₂)₄-0-(CH₂)₃-OH,

-(CH₂)₄-0-(CH₂)₄-OH;-S-CH₂-OH, -S-(CH₂)₂-OH, -S-(CH₂)₃-OH, -S-(CH₂)₄-OH, -CH₂-S-CH₂-OH, -CH₂-S-(CH₂)₂-OH, -CH₂-S-(CH₂)₃-OH, -CH₂-S-(CH₂)₄-OH, -(CH₂)₂-S-CH₂-OH,

-(CH₂)₂-S-(CH₂)₂-OH, -(CH₂)₂-S-(CH₂)₃-OH, -(CH₂)₂-S-(CH₂)₄-OH, -(CH₂)₃-S-CH₂-OH,

-(GH₂)₃-S-(CH₂)₂-OH, -(CH₂)₃-S-(CH₂)₃-OH, -(CH₂)₃-S-(CH₂)₄-OH, -(CH₂)₄-S-CH₂-OH,

-(CH₂)₄-S-(CH₂)₂-OH, -(CH₂)₄-S-(CH₂)₃-OH, -(CH₂)₄-S-(CH₂)₄-OH;-NR³-CH₂-OH, -NR³-(CH₂)₂-OH, -NR³-(CH₂)₃-OH, -NR³-(CH₂)₄-OH, -CH₂-NR³-CH₂-OH, -CH₂-NR³-(CH₂)₂-OH,

-CH₂-NR³-(CH₂)₃-OH, -CH₂-NR³-(CH₂)₄-OH, -(CH₂)₂-NR³-CH₂-OH, -(CH₂)₂-NR³-(CH₂)₂-OH, -(CH₂)₂-NR³-(CH₂)₃-OH, -(CH₂)₂-NR³-(CH₂)₄-OH, -(CH₂)₃-NR³-CH₂-OH, -(CH₂)₃-NR³-(CH₂)₂-OH, -(CH₂)₃-NR³-(CH₂)₃-OH, -(CH₂)₃-NR³-(CH₂)₄-OH, -(CH₂)₄-NR³-CH₂-OH, -(CH₂)₄-NR³-(CH₂)₂-OH, -(CH₂)₄-NR³-(CH₂)₃-OH, -(CH₂)₄-NR³-(CH₂)₄-OH (R³ is the same as defined above), and the like. The R² moieties preferably have the ether bonds and more preferably have the ether bonds within the main chain.

[0029] A method for manufacturing the carbinol group-containing cyclic organopotysiloxane is not particularly limited, but is preferably prepared via a hydrosilylation reaction of a cyclic polyorgano hydrogensiloxane and an alcoholic hydroxyl group-containing compound having unsaturated bonds.

[0030] The cyclic polyorgano hydrogensiloxane is not particularly limited provided that it has at least one silicon-bonded hydrogen atom. Examples thereof include compounds expressed by the following formula:

In this formula, "p" is an integer from 2 to 8 and preferably an integer from 4 to 6;

"q" is an integer from 0 to 4 and preferably is 0;

p≥q; and

3≤p+q≤8 and preferably 4≤p+q≤6. Specific examples of the cyclic polyorgano

hydrogensiloxane include trimethylcyclotrisiloxane, tetramethyl cyclotetrasiloxane,

pentamethylcyclopentasiloxane, and the like.

[0031] The alcoholic hydroxyl group-containing compound having unsaturated bonds is not particularly limited provided that it has at least one unsaturated bond and at least one alcoholic hydroxyl group, and the unsaturated bond is preferably an unsaturated aliphatic bond. Thus, the alcoholic hydroxyl group-containing compound having unsaturated bonds preferably has an unsaturated aliphatic group; more preferably has a vinyl group, an allyl group, a butenyl group, or a similar alkenyl group; and even more preferably has an allyl group.

[0032] Examples of the alcoholic hydroxyl group-containing compound having unsaturated bonds include allyl alcohol, 1-buten-4-ol, 1-buten-3-ol, 2-buten-1-ol, 2-methyl-1-buten-2-ol, 1-penten-5-ol, 2-penten-5-ol, 1-hexen-5-ol, 1-hexen-6-ol, 1-octen-8-ol, 3-methyl-2-propen-1-ol, cinnamic alcohol , 2-methyl-2-buten-1-ol, 3-methyl-2-buten-1-ol, 2,3-dimethyl-2-buten-1-ol, 1 ,3-pentadien-5-ol, 1 ,4-pentadien-3-ol, 1 ,3-hexadien-6-ol, 2,4-hexadien-1-ol, 3-cyclohexenol,

2- vinylphenol, 3-vinylphenol, 4-vinylphenol, 3-fluoro-5-vinylphenol, 3-allylphenol, 4-allylphenol, 3,5-diallylphenol, 3-isopropenylphenol, 4-isopropenylphenol, 3-vinylbenzyl alcohol, 4-vinylbenzyl alcohol, 3-hydroxystyrene, 4-hydroxystyrene, 3-vinyl-8-naphthol, 9-vinyl-10-anthrol,

4-vinyl-4-biphenol, and similar alkenyl alcohols.

[0033] The alcoholic hydroxyl group-containing compound having unsaturated bonds can have ether bonds, thioether bonds, or imino bonds, but preferably has ether bonds. Examples of the alcoholic hydroxyl group-containing compound having unsaturated bonds having ether bonds include 2-allyloxy-ethanol, 1-allyloxy-2-propanol, 3-allyloxy-1-propanol,

3- allyloxy-1 ,2-propanediol, and similar compounds having allyloxy groups. Examples of the alcoholic hydroxyl group-containing compound having thioether bonds or imino bonds include 2-allylthio-ethanol, 1-allylthio-2-propanol, 3-allylthio-1-propanol, 3-allylthio-1 ,2-propanediol, and similar compounds having allylthio groups; and 2-allylimino-ethanol, 1-allylimino-2-propanol, 3-allylimino-1-propanol, 3-allylimino-1 ,2-propanediol, and similar compounds having allylimino groups.

[0034] The hydroxyl group of the alcoholic hydroxyl group-containing compound having unsaturated bonds is preferably protected. The form of the protection is not particularly limited, but preferably the hydroxyl group of the alcoholic hydroxyl group-containing compound having unsaturated bonds is converted to a silyl ether using a silylating agent such as a

hexamethyldisilazane. The silyl ether can be reconverted to a hydroxyl group via hydrolysis after the hydrosilylation reaction.

[0035] The hydrosilylation reaction can be carried out using a technique known and commonly used in the art. The hydrosilylation reaction is preferably performed in the presence of a catalyst. Examples of the catalyst include platinum, ruthenium, rhodium, palladium, osmium, iridium, and similar compounds, and platinum compounds are particularly effective due to their high catalytic activity. Examples of the platinum compound include chloroplatinic acid; platinum metal; platinum metal supported on a carrier such as platinum supported on alumina, platinum supported on silica, platinum supported on carbon black, or the like; and a platinum complex such as platinum-vinylsiloxane complex, platinum-phosphine complex, platinum-phosphite complex, platinum alcoholate catalyst, or the like. A usage amount of the catalyst is about 0.5 to 1000 ppm in terms of platinum metal, when using a platinum catalyst.

[0036] The present invention also relates to a method for enhancing hardness and/or scratch resistance of a cured product of a curable composition, the method comprising compounding a carbinol group-containing cyclic organopolysiloxane in said curable composition.

[0037] The additive for a curable composition of the present invention contains a carbinol group-containing cyclic organopolysiloxane as an essential component. A ratio of the carbinol group-containing cyclic organopolysiloxane present in the additive for a curable composition of the present invention can, for example, be from 50 to 100 wt.% (mass%), and is preferably from 70 to 100 wt.% (mass%), more preferably from 90 to 100 wt.% (mass%), even more preferably from 98 to 100 wt.% (mass%), and particularly preferably is 100 wt.% (mass%).

[0038] The additive for a curable composition of the present invention can contain at least one type of solvent as an optional component. The solvent is not particularly limited, and examples thereof include methanol, ethanol, isopropyl alcohol, butanol, isobutyl alcohol, ethylene glycol, diethyleneglycol, triethyleneglycol, ethyleneglycol monomethyl ether, diethyleneglycol monomethyl ether, triethyleneglycol monomethyl ether, propyleneglycol monomethyl ether, polyethyleneglycol monomethyl ether (PGME), and similar alcohols; acetone, methyl ethyl ketone, methyl isobutyl ketone, and similar ketones; toluene, xylene, and similar aromatic hydrocarbons; hexane, octane, heptane, and similar aliphatic hydrocarbons; chloroform, methylene chloride, trichloroethylene, carbon tetrachloride, and similar organic chlorinated solvents; ethyl acetate, butyl acetate, isobutyl acetate, and similar esters; and the like. A ratio of the solvent present in the additive for a curable composition of the present invention can, for example, be from 0 to 50 wt.% (mass%), and is preferably from 0 to 30 wt.% (mass%), more preferably from 0 to 10 wt.% (mass%), even more preferably from 0 to 2 wt.% (mass%), and particularly preferably is 0 wt.% (mass%).

[0039] The curable composition of the present invention contains the additive of the present invention as an essential component. Thus, the curable composition of the present invention contains the carbinol group-containing cyclic organopolysiloxane described above as an essential component. Moreover, because the curable composition of the present invention contains the carbinol group-containing cyclic organopolysiloxane, the hardness and/or scratch resistance of a cured product of said curable composition is excellent.

[0040] A ratio of the additive of the present invention present in the curable composition of the present invention is not particularly limited and, for example, can be from 0.1 to 50 wt.%

(mass%), and is preferably from 1 to 40 wt.% (mass%), more preferably from 2 to 30 wt.%

(mass%), even more preferably from 3 to 20 wt.% (mass%), and particularly preferably from 4 to 10 wt.% (mass%). Thus, the ratio of the carbinol group-containing cyclic organopolysiloxane present in the curable composition of the present invention is not particularly limited and, for example, can be from 0.1 to 25 wt.% (mass%), and is preferably from 1 to 20 wt.% (mass%), more preferably from 2 to 15 wt.% (mass%), even more preferably from 3 to 10 wt.% (mass%), and particularly preferably from 4 to 5 wt.% (mass%).

[0041] The curable composition of the present invention is not particularly limited provided that it is curable, but preferably is a curable composition for coating an arbitrary substrate, and more preferably is a coating. The form of the curing is not particularly limited and said curing may take the form of room temperature curing, room temperature drying, or heated curing.

Additionally, the form of the curable composition is not particularly limited and may be either liquid or solid but, from the perspective of handling, is preferably liquid.

[0042] The substrate is not particularly limited and various types of inorganic substrates and organic substrates, or combinations thereof can be used. Examples of inorganic substrates include substrates formed from aluminum or a similar metal. Examples of organic substrates include substrates formed from organic resins, wood, paper, or similar substances. More specific examples of the organic resins include fluoro resins, acrylic resins, polyethylenes, polypropylenes, polycarbonates, polyacrylates, polyesters, polyamides, polyurethanes, ABS resins, polyvinyl chlorides, silicones, acrylic silicones, and similar modified silicones. Among these, silicones, modified silicones, polyvinyl chloride, fluoro resins, polycarbonates, and acrylic polymers are preferable. The form of the substrate is not particularly limited and can be any shape desired such as cubic, rectangular solid, spherical, sheet-like, and the like. Note that the substrate may also be porous.

[0043] The coating-use curable composition, preferably the curable coating, of the present invention can contain urethane resin, acrylic resin, polyester resin, epoxy resin, alkyd resin, silicone resin, rubber, or similar resins or rubbers and, as necessary, crosslinking agent as a coating film-forming component. Among these, the coating-use curable composition of the present invention is preferably a urethane-based coating having urethane resin as a base.

[0044] Urethane resin is a polymeric compound having urethane bonds -NHCOO- in the main chain and typically is produced from a polyisocyanate and a polyol.

[0045] Examples of the polyisocyanate include aliphatic, cycloaliphatic, aromatic, and heterocyclic polyisocyanates and oligomers thereof, carbodiimide-modified products, polyol-modified products, allophanate-modified products, and the like thereof. One type of polyisocyanate may be used or a combination of two or more polyisocyanates may be used. Specific examples of the aliphatic polyisocyanate include ethylene diisocyanate,

1 ,4-tetramethylene diisocyanate, 1 ,6-hexamethylene diisocyanate, 1 ,12-dodecane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, lysine diisocyanate, and the like. Specific examples of the cycloaliphatic polyisocyanate include cyclobutane-1 ,3-diisocyanate, cyclohexane-1 ,3-and-1 ,4-diisocyanate, isophorone diisocyanate, 4,4'-methylene bis(cyclohexyl isocyanate),

methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate,

1 ,3-(isocyanatomethyl)cyclohexane, and the like. Specific examples of the aromatic

polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, m-tetramethyl xylylene diisocyanate, p-tetramethyl xylylene diisocyanate, methyltris (4-phenyl isocyanate),

tris(4-isocyanate phenyl)methane, thiophosphoric tris(4-isocyanate phenyl ester),

3-isopropenyl-a',a'-dimethylbenzyl isocyanate, and oligomer mixtures thereof or, alternatively, carbodiimide-, polyol-, and allophanate-modified products of polyisocyanate compounds thereof.

[0046] The oligomer of the polyisocyanate can be obtained, for example, by oligomerizing a diisocyanate by forming burette bonds, urea bonds, isocyanurate bonds, urethane bonds, allophanate bonds, uretdione bonds, or the like. From the perspective of the balance between the hardness and the flexibility of the polyurethane resin coating resulting from the reaction with the polyol, an oligomer of an aliphatic polyisocyanate or similar polyisocyanate is preferably used.

[0047] A compound or polymer having two or more hydroxyl groups in the molecule can be used as the polyol. Examples of the polyol include diol, triol, tetraol, pentitol, and hexitol; a saturated or unsaturated polyester (hereinafter referred to as "polyester polyol"), polyether (hereinafter referred to as "polyether polyol"), acrylic polymer (hereinafter referred to as "polyacrylic polyol"), or polycaprolactone having two or more hydroxy! groups in the molecule; a saturated or unsaturated oil-modified or fatty acid-modified alkyd resin, aminoalkyd resin, polycarbonate, epoxy resin, polyurethane, cellulose acetate butyrate resin, fluorine-containing resin, or similar polymer polyol; and the like.

[0048] Examples of the diol include ethylene glycol, propylene glycol, β, β'-dihydroxy diethylether (diethyleneglycol), dipropylene glycol, 1 ,4-butylene glycol, 1 ,3-butylene glycol,

polyethyleneglycol, polypropylene glycol, polypropylene-polyethyleneglycol, polybutyleneglycol, and the like. Examples of the triol include glycerin, trimethylolpropane, 1 ,2,6-hexanetriol, and the like. Examples of the tetraol include pentaerythritol, 2-methylglucoside, and the like.

Examples of the hexitol include sorbitol and the like.

[0049] The polyester polyols can be obtained via a condensation reaction of adipic acid, dimer acid, phthalic anhydride, isophthalic acid, or a similar polybasic acid, and ethylene glycol, diethyleneglycol, propylene glycol, trimethylolpropane, glycerin, or a similar diol or triol.

Additionally, the polyether polyol includes a product in which propylene oxide, ethylene oxide, or the like is added to glycerin, propylene glycol, or a similar polyhydric alcohol; or a product rich in hydroxyl groups obtained by reacting an ethylenediamine, ethanolamine, or a similar

polyfunctional compound with ethylene oxide or propylene oxide.

[0050] Furthermore, the polyacrylic polyol can be obtained by copolymerizing a polymeric acrylic monomer having one or more hydroxyl groups in the molecule and another monomer that is copolymerizable therewith. Examples of the polymeric acrylic monomer having one or more hydroxyl groups in the molecule include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, glycerol monoester (meth)acrylate,

trimethylolpropane monoester (meth)acrylate, 2-hydroxy (meth)acrylate-3-chloropropyl, and similar (meth)acrylic ester having hydroxyl groups; or, alternatively, a ring-opening

polymerization adduct of the (meth)acrylic ester having hydroxyl groups described above and a lactone such as ε-caprolactone, γ-valerolactone, and the like.

[0051] Examples of the other monomer that is copolymerizable with the (meth)acrylic ester having the hydroxyl groups in the molecule include (meth)acrylate or methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, decyl (meth)acrylate,

2-ethylhexyl(meth)acrylate, lauryl (meth)acrylate, and similar (meth)acrylic esters; styrene or a-methylstyrene, β-chlorostyrene, and similar styrene derivatives; vinyl acetate, vinyl propionate, vinyl isopropionate, and similar vinyl esters; and (meth)acrylonitrile and similar nitriles.

Additionally, a polymerizable adduct obtained via an addition reaction of acrylic acid or methacrylic acid and a monoepoxy compound or an epoxy resin, or the like can be used.

[0052] The production of the polymer polyol obtained by copolymerizing the monomers described above can be carried out via a known polymerization process such as solution polymerization, block polymerization, emulsion polymerization, suspension polymerization, or the like. A mixture of two or more types of these polyols may also be used. Typically, the polyester polyol or the polyacrylic polyol is preferably used. A hydroxyl value of the polyol is preferably from 1 to 1 ,000 mg KOH/g and more preferably from 10 to 500 mg KOH/g. The hydroxyl value is preferably not less than 1 mg KOH/g because the polyurethane resin coating film will be tough, and the hydroxyl value is preferably not more than 1 ,000 mg KOH/g because the flatness of the surface and the flexibility of the polyurethane resin coating film will improve.

[0053] A number-average molecular weight of the polyol is preferably about 300 to 20,000, and is more preferably about 500 to 12,000. The number-average molecular weight is preferably not less than 300 because the mechanical physical properties of the cured coating film will be high. The number-average molecular weight is preferably not more than 20,000 because the viscosity of the polyol will be low, and the diluent solvent needed in order to adjust the coating viscosity to a viscosity appropriate for application will either be unnecessary, or needed in only a small amount. In order to achieve a coating with a low VOC (volatile organic product) concentration (described below), a polyol with a number-average molecular weight of about 500 to 5,000 is preferably used.

[0054] In the urethane-based coating of the present invention, a ratio (molar ratio) of the isocyanate groups to the hydroxyl groups (NCO/OH) is preferably from 0.1 to 5.0 and more preferably from 0.3 to 3.0. It is not preferable that the ratio is less than 0.1 because the polyurethane resin coating film may become fragile; and it is not preferable that the ratio exceeds 5.0 because the mechanical physical properties of the polyurethane resin coating film may be adversely affected due to the abundant presence of polyisocyanates, which do not contribute to crosslinking. The urethane-based coating of the present invention may be a single pack or a two pack urethane-based coating.

[0055] The coating-use curable composition, and preferably the coating, of the present invention may contain a solvent as necessary. Examples of the solvent include benzene, toluene, xylene, aromatic naphtha, and similar hydrocarbon solvents; ethyl acetate, butyl acetate, cellosolve, hexyl acetate, amyl acetate, ethyl propionate, butyl propionate, and similar ester solvents;

acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, and similar ketone solvents; ethyleneglycol monoethyl ether acetate,

diethyleneglycol monoethyl ether acetate, and similar glycol ester solvents; and the like. A mixture of two or more types of these solvents may also be used.

[0056] The coating-use curable composition, and preferably the coating, of the present invention may, as necessary, be an aqueous coating-use curable composition in which a neutralizing agent or a surfactant has been compounded and emulsified/dispersed in an aqueous medium.

[0057] The neutralizing agent is not particularly limited provided that it can neutralize carboxyl groups or amino groups, and examples thereof include sodium hydroxide, potassium hydroxide, trimethylamine, dimethylaminoethanol, 2-methyl-2-amino propanol, triethylamine, ammonium, formic acid, acetic acid, lactic acid, and phosphoric acid. Examples of the surfactant include polyoxyethylene nonylphenyl ether, polyoxyethylene-oxypropylene block copolymers, and similar nonionic surfactants; and sodium lauryl sulfate, sodium dodecylbenzenesulfate, and similar anionic surfactants.

[0058] Examples of the aqueous medium include water; a water-organic solvent mixture solution having principally water, wherein a water soluble organic solvent or similar organic solvent is dissolved in water; and the like.

[0059] The coating-use curable composition of the present invention may further comprise pigments such as titanium oxide, ultramarine blue, Prussian blue, zinc oxide, red iron oxide, chrome yellow, lead white, carbon black, iron oxide, aluminum powder, and similar inorganic pigments; azo pigments, triphenylmethane pigments, quinoline pigments, anthoraquinone pigments, phthalocyanine pigments, and similar organic pigments; fine quartz powder, calcium carbonate powder, diatomaceous earth powder, aluminum hydroxide powder, particulate alumina, magnesia powder, zinc oxide powder, hollow fillers, and similar bulking fillers; platinum compounds, aerosol titanium dioxide, zinc carbonate powder, carbonic acid manganese powder, and similar flame retardants; and the like. Furthermore, as necessary, rust inhibitors, UV absorbers, photostabilizers, drip inhibitors, leveling agents, and similar additives may be included.

[0060] The coating-use curable composition of the present invention can be easily manufactured by placing the additive of the present invention containing the carbinol group-containing cyclic organopolysiloxane and, as necessary, the other optional components in a known kneading device such as a Roth mixer, Hobart mixer, Turello mixer, Henschel mixer, kneader mixer, flow jet mixer, ball mill, oscillating mill, paddle mixer, ribbon mixer, or similar kneading device, and kneading, preferably under sealed conditions. The mixture may be heated when kneading and a heating temperature is preferably from 30 to 200°C. The order in which the components are kneaded can be selected as desired. Examples include a method in which all of the

components are kneaded simultaneously and a method in which the components that begin curing when added are kneaded last.

[0061] The coating-use curable composition, and preferably the coating, of the present invention can be applied on a substrate via a conventionally known process such as, for example, immersing, spraying, brush application, blade coating, and the like. One coat may be applied or a plurality of coats may be applied on top of each other. After the application, the coating film can be obtained by allowing the applied coating to rest as-is and cure under heated or room temperature conditions, preferably under room temperature conditions. A thickness of the coating film can be set as desired, but is preferably from 1 to 500 μιη.

[0062] The curable coating of the present invention may contain a catalyst for the purpose of promoting the drying and curing of the coating film. For example, dimethylethanol amine, triethylene diamine, and similar tertiary amines; and stannous octoate, dibutyltin dilaurate, and similar organic tin salts can be used as the catalyst.

[0063] The coating film obtained via the present invention can exert high hardness and/or excellent scratch resistance, and because both high hardness and excellent scratch resistance can be simultaneously obtained, the coating film can be advantageously formed on the surface of an arbitrary article. Particularly, the coating film obtained via the present invention can be advantageously used as a coating for automobiles, aircraft, trains, and other transportation equipment.

EXAMPLES

[0064] Hereinafter, the present invention is described with reference to examples, but it should be understood that the present invention is not limited to these examples.

[0065] Synthesis Example 1 : <Synthesis of TMS-protected allyl glycol>

237 g of hexamethyldisilazane and 0.049 g of trifluoroacetic acid were introduced into a reaction vessel provided with an agitator, a thermometer, a reflux tube, and a dropping funnel, and heated and agitated to 100°C. 250 g of allyl glycol was added in small portions from the dropping funnel and the reaction was initiated. The reaction occurred instantly, and was accompanied by the generation of ammonia. Following completion of the dropwise adding, ablation of the allyl glycol of the raw material was confirmed via gas chromatography. The reflux tube was switched to the distillation tube and the low volatile content was removed under reduced pressure.

Furthermore, 360 g (85% yield) of the allyl glycol trimethylsilyl (TMS) protected product was obtained as a transparent liquid through reduced pressure distillation (81 °C, 32 mmHg).

[0066] Synthesis Example 2: <Synthesis of carbinol-modified cyclic organopolysiloxane> 250 g of the allyl glycol TMS protected product obtained in Synthesis Example 1 was introduced into a reaction vessel provided with an agitator, a thermometer, a reflux tube, and a dropping funnel, and heated and agitated to 65°C. 68.9 g of tetramethyl cyclotetrasiloxane and 0.080 g of a platinum catalyst (1 ,3-divinyltetramethyl disiloxane platinum complex in toluene solution; platinum metal content: about 4,000 ppm) were each divided and added in eight cycles and hydrosilylation was carried out. The completion of the reaction was confirmed via a hydrogen generation process. The low volatile content was removed by heating up to 100°C under reduced pressure (20 mmHg). Thereafter, 184 g of methanol and 2.2 g of acetic acid were newly added, and the mixture was heated and agitated to 60°C. A deprotection reaction to remove the TMS was carried out for seven hours under methanol reflux. After completion of the deprotection, the methanol and the acetic acid were stripped under reduced pressure and 146 g (78% yield) of a carbinol-modified cyclic organopolysiloxane was obtained as a light yellow liquid. The resulting product was confirmed using NMR, which revealed the kinetic viscosity at 25°C to be 1 ,680 mm /s.

[0067] The synthesis scheme of the carbinol-modified cyclic organopolysiloxane of Synthesis Example 2 is described below. Note that "Me" means "methyl group".

[0068] Practical Example 1 : Preparation of urethane coating agent>

A mixed liquid was obtained by compounding the various carbinol group-containing

organopolysiloxanes shown in Tables 1 and 2 at predetermined amounts (concentration of 2 wt.% or 5 wt.%) with a commercially available polyol (Product name: Desmophen A870, manufactured by Sumika Bayer Urethane Co., Ltd.), and mixing thoroughly. Urethane coating agents of Practical Examples 1 and 2 and Comparative Examples 1 to 8 were prepared by compounding, in 100 parts by weight of the mixed liquid described above, 5 parts by weight of butyl acetate, 5 parts by weight of xylene, and an isocyanate curing agent (Product name:

Sumidur N330, manufactured by Sumika Bayer Urethane Co., Ltd.) at an amount where the carbinol groups and the isocyanate groups will be 1 :1 equivalent weight. Additionally, a reference urethane coating agent was prepared in the same way, with the exception that only the polyol was used in place of the mixed liquid.

[0069] Evaluation

The urethane coating agents of Practical Examples 1 and 2 and Comparative Examples 1 to 8 were applied on a black vinyl chloride panel and allowed to sit at rest for three days at room temperature. Thus, cured coating films were obtained.

[0070] Coating film pencil hardness

Pencil hardness of each of the coating films was measured in accordance with JIS K5600-5-4.

[0071] Scratch resistance

An initial 20° gloss value of the cured coating films was measured using a surface glossimeter. Thereafter, the cured coating film surfaces were scratched by rubbing steel wool 10 times back and forth with a load of 100 g on the cured coating film surfaces. Then, the cured coating film surfaces were washed for one minute using water at a flow rate of 5 LAnin and dried. Thereafter, the 20° gloss value was measured again using the surface glossimeter. Results are shown in Tables 1 and 2.

[0072] Table 1

* In Table 1 , "Comp. Ex." is an abbreviation for "Comparative Example."

[0073] Table 2

* In Table 2, "Comp. Ex." is an abbreviation for "Comparative Example."

[0074] Organopolysiloxane 1 : Carbinol-modified cyclic organopolysiloxane (kinetic viscosity at

25°C: 1 ,680 mm²/s) prepared in Synthesis Example 2 [0075] Organopolysiloxane 2: Organopolysiloxane expressed by the following formula:

[(CH₃)₂Si0_2/2]₂3[(CH₃)R'Si0_2/2]4[(CH₃)₃Si0_1/2]₂

R';-(CH₂)₃-0-(CH₂)₂-OH

(kinetic viscosity at 25°C: 250 mm²/s)

[0076] Organopolysiloxane 3: Organopolysiloxane expressed by the following formula:

[(CH₃)₂Si0_2/2]₇[(CH₃)R^,Si0_2/2]3[(CH3)₃Si0_1/2]₂

R';-(CH₂)₃-(0-(CH₂)₂)₁₂-OH

(kinetic viscosity at 25°C: 285 mm²/s)

[0077] Organopolysiloxane 4: Organopolysiloxane expressed by the following formula:

[(CH3)₂Si0_2/2]₁₄[(CH3)₂ R'Si0_1/2]₂

R';-(CH₂)₃-(0-(CH₂)₂)₁₂-OH

(kinetic viscosity at 25°C: 308 mm²/s)

[0078] Organopolysiloxane 5: Organopolysiloxane expressed by the following formula:

[(CH₃)₂Si0_2/2]₁₄[(CH₃)₂ R'Si0_1/2]₂

R';-(CH₂)₃-0-(CH₂)₂-OH

(kinetic viscosity at 25°C: 45 mm²/s)

[0079] As is clear from Tables 1 and 2, the coatings of Practical Examples 1 and 2, which contained the carbinol-modified cyclic organopolysiloxane of Synthesis Example 2, formed coating films having high hardnesses and excellent scratch resistance.

[0080] On the other hand, both high hardness and excellent scratch resistance could not be achieved using the coating films obtained from the coatings of Comparative Examples 1 to 8, which contained carbinol-modified linear organopolysiloxanes.

Claims

I . An additive for a curable composition containing a carbinol group-containing cyclic

organopolysiloxane as an active component for enhancing hardness and/or scratch resistance of a cured product.

2. The additive according to claim 1 , wherein kinetic viscosity at 25°C is from 0.1 to 10,000 mm²/s.

3. The additive according to claim 1 or 2, wherein the carbinol group-containing cyclic organopolysiloxane is expressed by the following general formula (1):

[R¹R²Si0_2/2]_n [R¹ ₂Si0_2/2]_m (1)

wherein R are each independently substituted or unsubstituted straight or branched monovalent hydrocarbon groups having from 1 to 20 carbons;

R² are each independently substituted or unsubstituted straight or branched monovalent hydrocarbon groups having from 1 to 20 carbons and at least one hydroxyl group; "n" is an integer from 2 to 8; "m" is an integer from 0 to 4; n≥m; and 3≤n+m≤8.

4. The additive according to claim 3, wherein the "n" moiety in general formula (1) is an integer from 4 to 6.

5. The additive according to claim 3 or 4, wherein the monovalent hydrocarbon groups having at least one hydroxyl group comprises ether bonds, thioether bonds, or imino bonds.

6. The additive according to any one of claims 1 to 5, wherein the carbinol group-containing cyclic organopolysiloxane is obtained via a hydrosilylation reaction of a cyclic polyorgano hydrogensiloxane and an alcoholic hydroxyl group-containing compound having unsaturated bonds.

7. The additive according to claim 6, wherein the alcoholic hydroxyl group-containing compound having unsaturated bonds comprises ether bonds, thioether bonds, or imino bonds.

8. The additive according to claim 6 or 7, wherein the alcoholic hydroxyl group is protected.

9. A curable composition containing the additive described in any one of claims 1 to 8.

10. The curable composition according to claim 9, which is a coating-use curable composition.

II . A curable coating comprising the coating-use curable composition described in claim 10.

12. The curable coating according to claim 11 , which is a urethane-based coating.

13. A cured coating film of the curable coating described in claim 11 or 12.

14. An article comprising the cured coating film described in claim 13.

15. A method for enhancing hardness and/or scratch resistance of a cured product of a curable composition, the method comprising compounding a carbinol group-containing cyclic

organopolysiloxane in said curable composition.