KR19980018050A - Thermosetting resin composition - Google Patents

Abstract

The present invention relates to (a) film-forming polyol resins, (b) curing agents reacting with polyol resins, (c) hydrolyzates / polycondensates of tri or tetraalkoxysilanes, and (d) polyol resins (a) and curing agents (b) A thermosetting resin or coating composition containing a catalyst for promoting the liver reaction.

Description

Thermosetting resin composition

The present invention relates to a thermosetting resin composition for paints.

Paint compositions for finishing building materials, fences, guardrails, road materials used as pillars or tunnel linings, vehicles, vehicles and other outdoor substrates, and oily marker ink, food, tobacco smoke, dust and dust-containing raindrops It is required to have resistance to staining or staining by. They also need to have resistance to acids or alkalis. Acid rain or acid exhaust gases can degrade or soil the coating. Coatings on building planks can be degraded by alkali contained in concrete or mortar walls. The coating film on a steel substrate is easy to decompose | disassemble by an alkaline cathode. Coatings applied to various indoor products such as home appliances, kitchen appliances, furniture and interior materials for construction also require resistance to staining by oily marker ink, food or tobacco smoke and resistance to alkaline detergents and alkaline cathodic decomposition. Hardness is one of the important properties of the coating to prevent it from being easily scratched by sand dust or cleaning brushes when exposed to the outdoors. Usually pencil hardness greater than 4H is required.

However, it is difficult for a coating film to satisfy both hardness requirements and all other requirements simultaneously. For example, resistance to staining by oily marker inks can be improved by incorporating silicone or fluorinated carbon resins into the paint composition, but this approach has other properties, including resistance to contamination by hardness and dust-containing raindrops. It is not effective to satisfy

JP-A-6145453, JP-A-7150102, JP-A-7068217 and WO 94/06879 disclose outdoor coating compositions consisting of a polymer containing a plurality of alkoxysilyl groups and optionally silanol groups. In this coating composition the polymer crosslinks with tetraalkoxysilane or its condensate. These compositions make the curing mechanism the silanol group condensation reaction between the silanol groups or the hydroxyl period of the polymer. The alkoxysilyl groups remaining in the surface portion of the coating film are hydrolyzed with silanol groups by rain or by treatment with an acid to increase the hydrophilicity of the surface so that the coating film is easily cleaned from contaminants adhered by rain or water washing. However, these compositions have some disadvantages. The -Si-O-Si or -Si-O-C- bonds formed by the curing reaction are easily broken by acids or alkalis, and microcracks occur when the alkoxysilyl group remains in the membrane body. The curing mechanism of these coating compositions is essentially the same as that of water-curable silicone rubber. As will be apparent from this they only have a limited shelf life or port life.

WO 95/17349 discloses suspensions containing reactive ultrafine silica particles having an inertia radius of 10 angstroms or less. This suspension is self-curing and provides a very hard film with a pencil hardness of at least 9H when applied to the substrate and then baked. Since this film consists essentially of amorphous silica, it is excellent in hardness and heat resistance, but poor in flexibility as compared with conventional organic polymer base resin compositions. Thus, the silica particle suspension itself is not suitable for the production of a conductive metal sheet (PCM) and for use in other applications where the painted substrate is subsequently subjected to mechanical treatment such as bending.

Therefore, there is a need for a thermosetting resin composition for paints capable of forming a cured film having a pencil hardness of 4H or higher without damaging other desired properties such as chemical resistance and stain resistance including acid resistance and alkali resistance.

[Overview of invention]

The present invention

(a) a film-forming polyol resin having a hydroxyl value of 5 to 300 and a number average molecular weight of 500 to 20,000,

(b) a curing agent reacting with the resin (a),

(c) hydrolysates / polycondensates of tri or tetraalkoxysilanes having a hydrolysis / dealcoholization rate of less than 100%, and

(d) a catalyst for promoting the reaction between the resin (a) and the curing agent (b)

It provides the thermosetting resin composition which consists of.

The present invention also provides a coating composition containing the thermosetting resin composition and the use of the coating composition.

The thermosetting resin composition of this invention is a mixed system which consists of a silicate component and an organic resin component. When the coating film of the composition is formed on a substrate and then baked, the silicate component cures itself by a self-condensation reaction which essentially forms inorganic amorphous silica particles dispersed in a matrix of organic resin components that are cured through reaction with an external curing agent. do. In addition, it is assumed that some of the hydroxyl groups of the resin component and some of the alkoxysilyl or silanol groups of the silicate component react with each other to bond these components into an integral membrane structure by chemical bonding. Thus individual components may each exhibit their own characteristics in the cured film. The silicate component mainly contributes to the hardness and the organic resin component shares other desirable properties. For example, the coating composition for conductive field metal plates can be prepared using a mechanically acting resin as the matrix resin. Membrane with high weather resistance and stain resistance is obtained by using a silicone or fluorine-containing resin as the matrix resin.

[Description of Preferred Embodiment]

Ingredient (a)

Polyol resins curable with external curing agents such as blocked polyisocyanates or antiplast resins are well known in the paint industry. Examples are acrylic polyol resins, polyester polyol resins, fluorine-containing polyol resins, silicone polyol resins and modified resins thereof. The polyol resin usable in the present invention has a hydroxyl value of 5 to 300, preferably 30 to 200, and a number average molecular weight of 500 to 20,000, preferably 1,800 to 20,000. If the hydroxyl value is too low, the polyol resin will not cure sufficiently. On the contrary, when the number of hydroxyl groups in the resin is too large, the cured film adversely affects the resistance to water, acid and alkali. The molecular weight of the resin is related to the mechanical strength of the cured film, but the resin having an excessively high molecular weight has too high a viscosity in the resin composition, thereby reducing the paintability of the composition by spraying or roller coating.

The polyol resin may be modified into suitable components or segments depending on the intended use of the coating composition. For example, acrylic or polyester polyols can be modified to have silicone segments. Polyol resins may also be modified to have functional groups other than hydroxyl groups such as carboxyl or alkoxysilyl. If the resin is modified to have an alkoxysilyl group, the modified resin preferably has an alkoxysilyl equivalent weight (molecular weight divided by the number of alkoxysilyl groups in the molecule) of greater than 650. Other parameters of the polyol resin should be within the ranges generally required for coating film forming resins. For example, Tg (glass transition temperature) is in the range of -20 ° C to 60 ° C. The resin with too low Tg does not provide a cured film having satisfactory mechanical strength. In contrast, resins with too high Tg result in a soft film that is susceptible to cracking. The acid value of the resin should be less than 30. The resin having an excessively high acid value catalyzes the hydrolysis or condensation of the remaining alkoxysilyl groups of the silicate component (c) and thus lowers the storage stability of the coating composition when exposed to atmospheric moisture. Further details regarding each polyol resin are provided below.

Acrylic polyol resin

Acrylic polyol resins are prepared by copolymerizing hydroxyl group-containing acrylic monomers with other ethylenically unsaturated monomers. Examples of hydroxyl group-containing acrylic monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate or other hydroxyalkyl (meth) Acrylate. Depending on the intended use, for example, for PCM, soft segment-containing monomers such as 2-hydroxyethyl (meth) acrylate-caprolactone adduct sold by Daicel Chemical Industries under the trade names PLACCEL FA and FM series, or Polyalkylene glycol mono (meth) acrylates can be combined with hydroxyalkyl (meth) acrylate monomers.

Examples of ethylenically unsaturated monomers copolymerizable with hydroxyl group-containing acrylic monomers include alkyl, such as methyl, ethyl, propyl, n-butyl, i-butyl, t-butyl, 2-ethylhexyl or lauryl (meth) acrylate ( Meth) acrylates; Aromatic vinyl monomers such as styrene or vinyltoluene; And other monomers such as acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid or glycidyl (meth) acrylate. Optionally 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, (meth) acrylamide, N-methyl or ethyl (meth) acrylamide or N, N-dibutoxymethyl (meth ) Acrylamide is also mentioned.

As described above, the acrylic polyol resin may be modified to have a plurality of alkoxysilyl group-containing pendant groups. These modified acrylic polyols contain a mixture of the hydroxyl group-containing monomer and another ethylenically unsaturated monomer with one ethylenically unsaturated group, hydrocarbon radicals such as 0-2 methyl groups, and one to three alkoxys all attached to the same silicon atom. It is prepared by copolymerizing with an alkoxysilane monomer having a group. Typical examples thereof include vinylmethyldimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylmethyldimethic. Oxysilane (KBM502), γ-methacryloyloxypropyltrimethoxysilane (KBM503), γ-methacryloyloxypropylmethyldiethoxysilane (KBE502), γ-methacryloyloxypropyltriethoxysilane (KBE503) and (gamma)-[2- (propen-2-yloxycarbonyl) benzoyloxy "propylmethyldimethoxysilane are mentioned. KBM502, KBM503, KBE502 and KBE503 are commercially available from Shin-Etsu Chemical. The proportion of alkoxysilane monomers is such that the weight of the alkoxysilyl equivalent of the resulting copolymer is greater than 650 and preferably greater than 900 and most preferably about 1500 days. Alkoxysilyl equivalent weight refers to the molecular weight divided by the number of alkoxysilyl groups in the molecule. When the alkoxysilyl equivalent weight is too small, i.e. when there are too many alkoxysilyl groups in the copolymer, the acid or alkali resistance of the coating is adversely affected by the formation of -Si-O-Si- and -Si-OC- bonds upon curing. It tends to become a gel when the paint composition is exposed to moist air, or easily cracks when a cured film is formed thereon.

Polyester polyol resin

As is well known in the art, polyester resins are polycondensates of polycarboxylic acid and polyhydric alcohol components. Examples of polycarboxylic acids include aromatic dicarboxylic acids and acid anhydrides such as terephthalic acid, isophthalic acid, phthalic acid and anhydrides thereof, 2,6-naphthalenedicarboxylic acid or 2,7-naphthalenedicarboxylic acid; And aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid or 1,4-cyclohexanedicarboxylic acid. Small proportions of γ-butyrolactone or ε-caprolactone; Their corresponding hydroxycarboxylic acids; aromatic hydroxy monocarboxylic acids such as p-hydroxyethoxybenzoic acid or p-hydroxybenzoic acid; And tri or tetracarboxylic acids such as trimellitic acid or pyromellitic acid may be incorporated into the acid component.

Examples of alcohol components include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol And bisphenol A-ethylene oxide adducts and bisphenol S-ethylene oxide adducts. 1,2-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 1,4-pentanediol, Branched chain aliphatic glycols such as 1,4-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,2-dodecanediol or 1,2-octanediol can also be used. The alcohol component may also comprise trivalent or tetrahydric alcohols such as trimethylolpropane, glycerin or pentaerythritol in small proportions.

The polyester polyol resin may contain a silicone or acrylic component incorporated into the resin molecule. The silicone component can be incorporated, for example, using polysiloxanes having a plurality of hydroxyalkyl groups as part of the polyhydric alcohol component. Such resins are commercially available from Hitachi Chemical Polymer, for example, under the trade name TA22-293J, which has a hydroxyl value of about 170 and a number average molecular weight MW of about 2,400.

Fluorine-containing polyol resin

Fluorine-containing polyol resins are prepared by copolymerizing (i) hydroxyl group containing radically polymerizable unsaturated monomers with (ii) fluorinated olefin monomers and optionally (iii) another radically polymerizable unsaturated monomer. Examples of the monomer (i) include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether or hydroxypentyl vinyl ether; And monoallyl ethers of mono, di or triethylene glycol.

Examples of the monomer (ii) include mono, di, tri or tetrafluorinated olefins such as vinyl fluoride, vinylidene fluoride, trifluorochloroethylene and tetrafluoroethylene.

The monomer (iii) is incorporated depending on the nature of the membrane required for the particular application. Examples include α-olefins such as ethylene, propylene or isobutylene; Vinyl ethers such as ethyl vinyl ether, isobutyl vinyl ether, butyl vinyl ether or cyclohexyl vinyl ether; Vinyl esters such as vinyl acetate, vinyl lactate, vinyl butyrate, vinyl isobutyrate, vinyl caproate or vinyl caprate; And isopropenyl esters such as isopropenyl acetate or isopropenyl propionate.

If necessary, the fluorine-containing polyol resin may have an acid value. This can be done by reacting a portion of the hydroxyl groups of the resin with a dicarboxylic acid anhydride such as succinic anhydride.

As used herein, the fluorine-containing polyol resin is intended to include a blend of a fluorine-containing resin having no hydroxyl group and an acrylic polyol resin as described above. The fluororesin free of hydroxyl groups may be a homopolymer of monomer (ii) or a copolymer of this and monomer (iii). The acrylic polyol resin may be a copolymer of monomer (i). Examples of copolymerizable monomers include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate; Alkyl (meth) acrylates; Ethylenically unsaturated carboxylic acids such as acrylic acid or methacrylic acid; Aromatic vinyl monomers such as styrene, α-methylstyrene or vinyl toluene; Amide monomers such as acrylamide, methacrylamide or derivatives thereof; And nitrile monomers such as acrylonitrile or methacrylonitrile.

Various fluororesins and hydroxyl group-containing fluororesins are commercially available. These are classified into polyvinylidene difluoride (PVDF) type, trifluoro and tetrafluoroethylene vinyl ether (FEVE) types. PVDE resins are available as KYNAR 500 from Elfatochem. This resin does not contain hydroxyl groups and is therefore used to mix with acrylic polyol resins. Examples of commercially available tri-FEVE resins are the LUMIFRON series sold by Asahi Glass, the FLUONATE series sold by Dainippon Ink And Chemicals, and the SEFRALCOAT series sold by Central Glass. An example of a tetra-FEVE resin is ZEFFLE sold by Daikin Industries. Acrylic fluorinated resins such as KOTAX sold by Toray Industries may also be used. These resins can be used as a blend with acrylic polyol resins or as such to adjust the hydroxyl value of the blend. Tri or tetra-FEVE resins are preferred in view of durability.

Silicone polyol resin

As used herein, silicone polyol resin refers to an organopolysiloxane having at least two hydroxyl groups in a molecule. As used herein, the modified silicone polyol resin refers to an organopolysiloxane mixed or grafted with another resin component.

The organopolysiloxane can be represented by the following formula (1).

[Formula 1]

Wherein R _a is methyl, C ₁ -C ₂₀ alkoxy, aryl, hydrogen or a monovalent C ₂ -C ₂₀₀ organic group optionally containing an ester, ether, urethane or carbon-carbon unsaturated group in the chain, R _b is terminal hydrate It is a monovalent organic group having a hydroxyl group and optionally having ester, ether, urethane or carbon-carbon unsaturated groups in the chain, m and n are integers satisfying the relationship of 0n4, 0m4 and 2fn + mf4, respectively. The silicone polyol resin of Formula 1 is disclosed in JP-A-2061481 mentioned above, the disclosure of which is incorporated herein by reference. The preferred organopolysiloxane of Formula 1 is that R _a is HOC ₂ H ₄ OC ₃ C ₆ c, R _b is methyl, propyl or phenyl, n and m are real numbers satisfying the relationship of 0n2, 0m2 and n + m3, respectively . Such silicone polyol resins are preferred for productivity, processability and curability. Particularly preferred resins are those of the formula (2).

[Formula 2]

Wherein R _a is methyl or phenyl, R _b is HOC ₂ H ₄ OC ₃ C _6- , x 0 or 1, y is an integer from 1 to 20, z is an integer from 1 to 10, R _a The mole percent of phenyl in is 10 to 50. Specific examples of such silicone polyols are also disclosed in JP-A-2061481 mentioned above. These resins have good compatibility with other polyol resins.

Silicone polyol resins are used as blends with other polyol resins having a hydroxyl number of 5 to 300. Acrylic polyol resins, polyester polyol resins or fluororesin polyols as described so far can be mixed with silicone polyol resins. Other hydroxyl group-containing resins such as alkyd resins, acrylic modified alkyd resins, acrylic modified polyester resins or epoxy resins derived from bisphenol A and epichlorohydrin may also be mixed. Alternatively, all or part of the other polyol resin may be chemically bonded by reacting with the silicone polyol resin. The process consists of reacting a hydroxyalkyl group containing trisiloxane with an ethylenically unsaturated compound having a functional group such as maleic anhydride to introduce ethylenic unsaturation into the siloxane, followed by copolymerizing the product with an acrylic or vinyl monomer.

The silicone polyol resin and the other polyol resin are combined in an increase ratio of 3 to 70 parts and 97 to 30 parts, preferably 5 to 40 parts and 95 to 60 parts, respectively. Silicone polyols can exhibit sufficient properties including weather resistance and chemical resistance. Excess proportions of silicone polyol resins are often incompatible with other polyol resins in the blend. By combining different polyol resins with silicone polyol resins, it is possible to adjust the compatibility with other additives, pigment dispersion stability, and other properties required for the film, including adhesion strength, elongation and hardness.

Component (b)

The first hardeners are blocked polyisocyanates. Polyisocyanates have at least two isocyanato groups in the molecule. Examples include aliphatic diisocyanates such as hexamethylene diisocyanate (HMDI) or trimethylhexamethylene diisocyanate (TMDI); Alicyclic diisocyanates such as isophorone diisocyanate (IPDI); Araliphatic diisocyanates such as xylene diisocyanate (XDI); Aromatic diisocyanates such as tolylene diisocyanate (TDI) or 4,4'-diphenylmethane diisocyanate (MDI); Dimer acid diisocyanate; Hydrogenated diisocyanates such as hydrogenated TDI (HTDI), hydrogenated XDI (H6XDI) or hydrogenated MDI (H12MDI); Dimers, trimers or high polymers of these diisocyanates; And adducts of diisocyanate and water or polyhydric alcohols.

Examples of blocking agents include oximes such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime or benzophenone oxime; Phenols such as M-cresol or xyleneol; Alcohols such as methanol, ethanol, butanol, 2-ethylhexanol, cyclohexanol or ethylene glycol monoethyl ether; lactams such as ε-caprolactam; Diketones such as diethyl malonate or acetoacetic acid esters; Mercaptans such as thiophenol; Urea such as thiourea; Imidazoles and carbamic acids.

Blocked polyisocyanates are prepared by reacting a polyisocyanate compound with a blocking agent until the free cyanato group disappears. Examples of commercially available products include DESMODUR series manufactured by Sumitomo Bayer Urethane, VERNOC D series manufactured by Dainippon Ink And Chemicals, TAKENATE B series manufactured by Takeda Chemical Industries, and CORONATE 2500 series manufactured by Nippon Polyurethane. Preference is given to oxime or lactam block polyisocyanates.

Secondary curing agents are aminoplast resins such as melamine resins, benzoguanamine resins, glycol urea resins and urea resins. Alkyl etherified melamine or benzoguanamine resins are preferred. Particularly preferred alkyl etherified melamine resins are those having methyl or butyl or both. These melamine resins are stable in storage and inherently hydrophobic upon storage. For this reason, this type of melamine resin migrates to the surface portion of the coating and increases the crosslink density of that portion compared to the rest of the membrane. As a result, the surface portion is less likely to be smeared or dirty. Such melamine resins are commercially available and examples thereof are listed below.

Benzoguanamine resin can also be used if it satisfy | fills the said requirement.

Component (c)

As is well known in the art, alkoxysilyl groups react with water to hydrolyze alkoxysilyl groups to hydrosilyl groups. The hydrosilyl group thus formed condenses with another alkoxysilyl group to produce alcohol as a byproduct. Water is also produced as a by-product by the condensation reaction of two silanol periods. As a result, once the hydrolysis reaction of the alkoxysilyl group is initiated, the reactions continue to occur in series until equilibrium is reached to provide a polycondensate polymer in which alcoholic by-products and a number of siloxy bonds are repeated. When the amount of water added to the reaction system is less than that required for 100% dealcoholization of the starting alkoxysilane, i.e., less than 1/2 mole relative to the total moles of alkoxysilyl groups, the polycondensate will contain a large number of silanol and It will have an alkoxysilyl group. Hydrolyzate / polycondensates of tri or tetraalkoxysilanes having a hydrolysis / dealcoholization rate of less than 100% as used herein refer to the above polymers having a large number of silyl and alkoxysilyl groups.

The starting alkoxysilane has the following formula (3).

[Formula 3]

Wherein R ¹ is C ₁ -C ₆ alkyl such as methyl, ethyl, propyl, butyl or pentyl, epoxyalkyl such as glycidoxypropyl or epoxycyclohexylethyl, aryl such as phenyl or benzyl, vinyl, allyl, acryl Alkenyl such as yloxypropyl or methacryloyloxypropyl, R ² is C ₁ -C ₆ alkyl such as methyl, ethyl, propyl, butyl or pentyl and n is 0 or 1. R ¹ groups denature hydrolysates / polycondensates to improve their reactivity or compatibility. Generally R ¹ is alkyl.

Specific examples of the alkoxysilane compound (silane monomer) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane or tetrabutoxysilane; And methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, benzyltrimethoxysilane, benzyltriethoxysilane, allyl Trialkoxysilanes such as trimethoxysilane or allyltriethoxysilane. The symbol n indicating the number of alkoxy groups is 0 or 1. The number of reactive alkoxysilyl or silanol groups decreases as the curability of the hydrolyzate / polycondensate decreases when starting from mono or dialkoxysilane. The number of carbon atoms in the alkyl group is preferably 1 to 3, namely methyl, ethyl or propyl. Methyl and ethyl are most preferred. When starting from an alkoxysilane having a large number of carbon atoms in the alkoxy group, its hydrolysis and condensation reactions are difficult to proceed, and the resulting product requires high temperature and a long time in the baking step of the coating film composition containing it. Thus, examples of preferred starting alkoxysilanes are tetramethoxysilane, tetraethoxysilane, ethyltrimethoxysilane and methyltriethoxysilane. Most preferred is tetramethoxysilane or tetraethoxysilane.

Hydrolysates / polycondensates are prepared in a known manner, ie by reacting the silane monomer with the required amount of water in the presence of a catalyst while removing alcohol in the reaction system. Optionally, starting from low molecular weight oligomers, oligomers of high polymerization degree can be prepared by similar reactions. The amount of water depends on the desired rate of hydrolysis / dealcoholation. 100% dealcoholization occurs when the molar amount of water is 1/2 to the total moles of alkoxysilyl groups present in the starting silane monomer or oligomer. The hydrolysis / dealcoholization rate or the hydrolysis rate used herein as a synonym thereof is calculated based on the amount of water actually used in the reaction relative to the amount of water needed to achieve 100% dealcoholation. The hydrolysis rate is theoretically greater than 0% but less than 100%. 100% hydrolyzate / polycondensate is solid silica and products with hydrolysis rates greater than 70% are solids or gels. Products having a hydrolysis rate of 60% to 70% are viscous and easily gel in the atmosphere with only trace amounts of water. They are unstable in storage. Hydrolysis rates of from about 30% to about 60% are preferred. However, products with higher hydrolysis rates can also be stable upon storage by selecting the appropriate solvent.

It is advantageous to use deionized water, pure water or ultrapure water for the reaction. Residues in water, such as ions present in water, can often degrade the performance of the coating. If necessary, a catalyst may be used in the reaction. Examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; Organic acids such as carboxylic acid or sulfonic acid; Inorganic bases such as ammonia and sodium hydroxide; And organic bases such as amines. Solvents such as alcohols, ethers or ketones may also be used in the reaction.

The resulting reaction product consists of an oligomer containing monomers, dimers, trimers or high polymers. If the reaction product contains excess monomers, the storage stability of the product itself or of the composition containing the product may be impaired. The presence of excess monomers can adversely affect coating performance, such as resistance to water, acids, alkalis and cracks. The monomer content is therefore reduced to less than 1% by weight, preferably less than 0.3% by weight, using known methods.

Hydrolyzates / polycondensates of tetramethoxysilanes containing less than 1% by weight of monomers are commercially available from Mitsubishi Chemical under the trade names MKC silicates MS51 and MS56.

This type of product is highly reactive and does not require high baking temperatures and long periods of time to bake the composition containing it. The hydrolysis rate is preferably in the range of 10% to 65%, more preferably 30% to 60%. The MKC silicate MS51 has a hydrolysis rate of about 40% and an SiO ₂ content of about 52%, and the MKC silicate MS56 has a hydrolysis rate of about 50% and an SiO ₂ content of about 56%.

Corresponding hydrolysates / polycondensates can be prepared from tetraethoxysilanes. In this case, the SiO ₂ content is usually about 40%. Examples of commercially available products include ES-40 manufactured by Colcoat, SILICATE 40 manufactured by Tama Chemical, TES 40 manufactured by Hoechst, SILBOND 40 manufactured by Stauffer, and ETHYL SILICATE 40 manufactured by Union Carbide.

Preferably the hydrolyzate / polycondensate appears as particles exhibiting an inertia radius of less than 100 Angstroms (10 nm) in an incineration X-ray scattering method. On the other hand, conventional silica such as fume silica used in the paint industry or wet silica such as silica sol has a particle size larger than 100 angstroms. In addition, the hydrolyzate / polycondensate used in the present invention contains more functional groups than conventional silica. That is, the hydrolyzate / polycondensate contains a total of 0.1 to 3 moles, preferably 0.5 to 2.7 moles of SiOH and SiOR groups per silicon atom. The molar ratio of SiOH to SiOR varies depending on the specific monomer, hydrolysis rate, dilution and the specific solvent used for the reaction. For example, transesterification can occur when different alcoholic solvents are used for the reaction and dilution. If the isolated hydrolyzate / polycondensate is suspended in isopropanol, 0.72 ± 0.13 moles of SiOH, 0.64 ± 0.12 moles of SiOEt and 0.30 ± 0.06 moles per silicon atom, as measured by H-NMR and CHN analysis, as measured by H-NMR and CHN analysis. SiOiPr. The amount of functional groups changes over time. When stored for 60 days at room temperature the values were changed to 0.4 mol, 0.36 mol and 0.17 mol, respectively. This proves that the hydrolyzate / polycondensate is chemically stable on storage. On the other hand, conventional silicas contain only traces of reactive groups. For example, about 100 angstroms of dry silica, available from Nippon Aerosil under the trade name AEROSIL 200, contains about 2 × 10 ^-5 moles of SiOH per silicon atom and a particle size of about 100 angstroms available from Nissan Chemical Industries. Silica sol contains 4x10 ^-5 moles of SiOH per silicon atom. These reactive groups are advantageously present in large amounts because they react with each other when baking the coating and also with the binder resin.

Most preferred hydrolyzates / polycondensates are reactive ultrafine silica particles disclosed in WO 95/17349. In short, this product is prepared starting from tetramethoxysilane or an oligomer thereof. The starting material is then hydrolyzed and condensed in the presence of more than 0.5 times the amount of water in a molar ratio relative to the total methoxy groups of the starting material, which is necessary to achieve 100% hydrolysis. The amount (molar ratio) of water relative to methoxy may range from 0.5 to 1.0, preferably from 0.5 to 0.75. Excess water often causes gelation. On the contrary, if the amount of water is insufficient, the reaction does not proceed satisfactorily.

The reaction can be carried out in the presence of a catalyst. Examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; Organic acids such as formic acid, acetic acid, propionic acid, oxalic acid, p-toluenesulfonic acid, benzoic acid, phthalic acid or maleic acid; Alkalis such as potassium hydroxide, sodium hydroxide, calcium hydroxide or ammonia; Organic tin compounds such as dibutyltin dilaurate, dibutyltin dioctoate or dibutyltin diacetate; Ammonium tris (aceylacetonate), titanium tetrakis (acetylacetonate), dibutoxytitanium bis (acetylacetonate), diisopropoxycitane bis (acetylacetonate), zirconium tetrakis (acetylacetonate), dibutane Chelates such as oxyzirconium bis (acetylacetonate) or diisopropoxyzirconium bis (acetylacetonate); And boron compounds such as boron butoxide or boric acid. Preference is given to acetic acid, maleic acid, metal alkoxides or boron compounds.

Silicate particles are present as suspensions in water or organic solvents. They have an inertia radius of less than 10 angstroms as measured by incineration X-ray scattering. The weight average molecular weight of the silica particles is between 1,000 and 3,000 by GPC method using polystyrene standard. Most of the particles have a weight average molecular weight of 1,400 to 2,000. The molar ratio of hydroxyl groups to methoxy groups usually exceeds 0.8. For this reason, silica particles have high storage stability and high reactivity. Silica particle suspensions can themselves form very rigid membranes having excellent heat resistance, fouling resistance and hot water resistance. Thus it surprisingly improves the hardness, alkali resistance and other properties of the coating film when incorporated into a coating formulation containing a polyol resin and a curing agent.

Diluents such as water or organic solvents may be added during or after the reaction of the starting materials. Any organic solvent conventionally used for coating compositions can be used. Examples thereof include alcohols such as methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, n-propyl alcohol, octanol or acetone alcohol; Ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Glycols such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate or propylene glycol monoethyl ether acetate; Hydrocarbons such as benzene, toluene, xylene or kerosene; Esters such as methyl acetate, ethyl acetate, butyl acetate or ethyl acetoacetate; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone or acetylacetone; And ethers such as ethyl ether, butyl ether, dioxane, furan or tetrahydrofuran. Alcohols such as methanol, ethanol, isopropanol or butanol are preferred for increasing storage stability. Since these solvents have a relatively low boiling point or flash point, high boiling point conventional hydrocarbon, glycol or ketone solvents can be mixed. The amount of alcoholic solvent is 5 to 5,000, preferably 100 to 1,000 parts by weight per 100 parts of tetramethoxysilane. When water is a diluent, water can be added by increasing the amount of water for reaction, or an additional amount of water can be added after completion of the reaction. Preferably water is used in an amount of 20 to 300 parts by weight per 100 parts of tetramethoxysilane including water for reaction. Suspension diluted with water adjusts the pH to less than 3, preferably 1 to 2, to prevent gelation.

The hydrolyzate / polycondensate can be treated with a silane coupling agent to control its reactivity. This treatment is effective for improving the storage stability of the coating composition containing it and also for improving the chemical resistance and other properties of the film of the composition.

Useful silane coupling agents for this purpose have the following formula (4).

[Formula 4]

Wherein R ³ is optionally a hydrocarbon residue containing a functional group, R ⁴ is C ₁ -C ₆ alkyl and m is 0, 1 or 2. Trimethoxysilane type coupling agents are preferred because of their reactivity with the hydrolyzate / polycondensate. Examples of the hydrocarbon residue R ³ include γ-methacryloylpropyl, γ-glycidoxypropyl, methyl, vinyl, phenyl, n-propyl, isobutyl, n-decyl, n-hexadecyl, trimethoxysilylhexyl, (gamma) -dibutylaminopropyl and nonafluoro butylethyl are mentioned.

Non-limiting examples of coupling agents include trimethylmethoxysilane, trimethylethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, n-decyltrimethoxy Silane, n-hexyltrimethoxysilane, 1,6-bis (trimethoxysilyl) hexane, γ-ureidopropyltrimethoxysilane, γ-dibutylaminopropyltrimethoxysilane, nonafluorobutylethyl tree Methoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacrylo Yloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, cyclohexylmethyldimethoxysil Column, vinyltrimethoxysilane, dimethyldimethoxysilane and octadecyldimethyl "3- (trimethoxysilyl) propyl" ammonium chloride.

The amount of the silane coupling agent has a molar ratio of 0.05 to 1 day relative to the sum of SiOH groups and SiOR groups present in the hydrolyzate / polycondensate. Excess amount of coupling agent may remain unreacted and adversely affect coating performance.

The treatment is carried out by leaving or stirring the mixture at room temperature for one day. If necessary, the mixture can be warmed at a suitable temperature to promote the reaction. While warming, care must be taken to properly control the temperature to prevent gelation or increase in viscosity of the mixture.

In general, hydrolyzates / polycondensates and even those prepared by conventional methods such as MKC silicates MS51 and MS56 available from Mitsubish Chemical, are effective in improving the hardness of coatings when applied to coating compositions according to the invention. This is because the reactive functional groups present in the hydrolyzate / polycondensate react with each other or with the binder resin to increase the apparent crosslink density of the cured film. In addition, since the reaction between the binder resin and the curing agent occurs preferentially during the baking step, the ratio of newly formed -Si-O-C- and -Si-O-Si- bonds in the cured film is minimized. This contributes to retaining the desired acid, alkali and hardness properties of the membrane. On the other hand, the use of conventional dry silica or silica sol having only traces of reactive groups cannot expect increased apparent crosslink density and hardness. Ultrafine silicas, such as fume silica, which are as fine as 100 angstroms in particle size, are known as thickeners and are widely used as sagging agents in the paint industry. It dramatically increases the viscosity of the paint composition even with the addition of 1% and therefore a higher percentage, such as 10%, is not suitable.

The use of the silica particle suspension disclosed in WO 95/17349 yields several further advantages.

This product is present as individual particles in the suspension and is rich in reactive functional groups. This causes individual particles to agglomerate into larger hard particles surrounded by a matrix of relatively soft resin during the curing step. For this reason, the hardness requirements are compatible with the flexibility and other mechanical strength requirements of the cured film.

Reactive functional groups present in this product can also react with functional groups present in the matrix resin. For this reason, its self-condensed hard particles are chemically bonded to the surrounding matrix resin in the cured film. For this reason, the presence of hard particles in the membrane does not adversely affect the mechanical strength of the membrane.

As mentioned above, the reaction between the binder resin and the curing agent occurs preferentially during the curing step. This prevents the formation of —Si—O—C— and —Si—O—Si— bonds, which weakens the film's resistance to alkalis and acids. As a result, a film having a pencil hardness greater than 4H can be obtained without impairing alkali resistance and acid resistance.

Component (d)

As is well known, block polyisocyanate-based curing agents require a catalyst. Examples include organotin compounds such as dibutyltin dilaurate, dibutyltin dioctoate or dibutyltin diacetate; And aluminum tris (acetylacetonate), titanium tetrakis (acetylacetonate), dibutoxytitanium bis (acetylacetonate), diisopropyltitanium bis (acetylacetonate), zirconium tetrakis (acetylacetonate), dibutoxy And chelates such as zirconium bis (acetylacetonate) or diisopropoxy zirconium bis (acetylacetonate). Usually tin catalysts are used.

When using aminoplast resins, acid catalysts are used. Examples include dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, p-toluenesulfonic acid and other aromatic sulfonic acids; Aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid and other organic phosphonic acids; And amine addition salts of these acids.

Optionally, a catalyst may be added to promote the reaction of the hydrolyzate / polycondensate. For this purpose the same catalysts used for the preparation of the hydrolyzate / polycondensate can be used. However, the silica particle suspensions disclosed in WO 95/17349 do not require such catalysts because of their high self-crosslinkability.

Resin composition

When the curing agent (b) is a blocked polyisocyanate, the polyol resin (a) and the curing agent (b) are combined in a block NCO / OH equivalent ratio of 0.8 to 1.5, preferably 1.0 to 1.2. The amount of catalyst (d) is generally 0.02 to 5 parts by weight, preferably 0.1 to 1.0 part by weight per 100 parts by weight of block polyisocyanate.

When the curing agent (b) is an aminoplast resin, the polyol resin (a) and the curing agent (b) are combined at a weight ratio of 6: 4 to 9: 1 as solid content. The amount of the acid catalyst is generally less than 5% by weight of the total of the polyol resin (a) and the curing agent (b) as solids, preferably 0.02% to 1.0% by weight. Excessive addition of the acid catalyst adversely affects the storage stability and other performance of the paint composition containing the resin composition.

The hydrolyzate / polycondensate (c) is incorporated at a ratio of 1 to 300 parts by weight, preferably 10 to 200 parts by weight, per 100 parts by weight of the total polyol resin component (a) and the curing agent (b) as solids. Excessive addition of component (c) may adversely affect the storage stability and paintability of the composition. Excessive component (c) in the composition leaves large amounts of unreacted SiOR or SiOH groups in the cured film, which is not only susceptible to cracking, but also results in degradation of acid, alkali and water resistance. The alkoxysilane hydrolyzate / polycondensate, which is mainly composed of linear molecules such as triethoxysilane hydrolyzate / polycondensate, in order to obtain the desired hardness, is generally a solid content of 50 per 100 parts by weight of the polyol resin component (a) and the curing agent (b). To 100 parts by weight. The silica particles disclosed in WO 95/17349 can be used in smaller amounts to obtain corresponding levels of hardness.

Paint Composition

The paint composition preferably mixes components (a) and (c) uniformly, disperses the pigment paste in the mixture, and finally with the usual additives such as solvents, if desired, the remaining components (b) and (d). It manufactures by incorporation.

Any solvent conventionally used for preparing the coating composition may be used. Examples include aromatic hydrocarbons such as toluene, xylene, Solveso 100 or Solveso 150; Esters such as ethyl acetate or butyl; Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone or isophorone; Alcohols such as butanol, octanol or diacetone alcohol; Ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether Glycol derivatives such as acetate or propylene glycol monoethyl ether acetate; And mixtures of these solvents.

Paint compositions may be colored pigments such as titanium dioxide, carbon black, iron oxides, various calcined pigments, cyanine blue or cyanine gray, depending on the intended use; Extender pigments such as calcium carbonate, clay or barium sulfate; Metal powder such as aluminum powder; Deglossants such as silica or alumina; It may contain other conventional additives such as defoamers, leveling agents, sagging agents, surface conditioners, viscosity modifiers, dispersants, ultraviolet absorbers or waxes.

Pigments are usually incorporated as pigment pastes prepared by pulverizing the pigment with part of the polyol resin (a) or with other pigment dispersion resins. Other methods may be used but the pigment paste is mixed with the remainder of the polyol resin (a) and the alkoxysilane hydrolyzate / polycondensate (c). Finally, the curing agent (b) and other additives are added to the mixture. To disperse pigments and other ingredients, roll mills, paint shakers, pot mills, dispersers, bead mills and other conventional machines can be used.

Any conventional coating method and apparatus may be used depending on the intended use, including roller coating, air spray coating, airless spray coating or curtain flow coating. The baking temperature will vary depending on the nature of the particular curing agent used and is generally 140 ° C to 240 ° C. The length of time is a function of baking temperature and is typically 30 seconds to 20 minutes. When a curing time of 30 seconds to 2 minutes is required, it is necessary to adjust the substrate temperature in the range of 190 ° C to 230 ° C. The paint composition of the present invention can be directly applied to a substrate, but for a use requiring high corrosion resistance and adhesion, the substrate may be epoxy primer, polyurethane modified epoxy, or two coat / 2 bake or two coat / 1 bake. It is preferable to coat with a primer coating such as a primer or a polyester primer and then to the paint composition of the present invention.

Substrates include galvanized steel sheets, galvanized steel sheets, zinc-aluminum coated steel sheets, aluminum-plated steel sheets, aluminum and aluminum alloys, stainless steel sheets, copper and copper alloys, titanium and titanium alloys, cold rolled steel sheets, metal deposition plates and metal sheets. Can be. Also included are plastics, plastic composites such as FRP, artificial marble and slate. Metal substrates may be surface treated with zinc phosphate, reactive chromate or chromate coatings. Thin films of organic composites can be applied to chromate treated surfaces.

The paint composition of the present invention can be used not only in the conductive field metal plate and the after-coating, but also in other applications requiring high hardness and high alkali resistance, as well as high stain-proof or anti-fouling property against rain, acid rain and exhaust gas. The coating compositions of the present invention are thus well suited for finishing building roofs and walls, road fences, columns, guardrails, beam coverings, tunnel linings, automobiles and aircraft.

EXAMPLE

The following examples are given for illustration only. All parts and percentages are parts by weight and percentages unless otherwise indicated.

Preparation Example 1-5

Acrylic polyol resin

80 parts of xylene and 20 parts of n-butanol were charged to a reaction vessel equipped with a stirrer, a reflux condenser and heating means, and then heated to 110 ° C. while stirring. To this was added dropwise the monomer mixture shown in Table 1 over 3 hours. After addition the mixture was kept at 110 ° C. for 30 minutes. Then 0.5 part of t-butylperoxy-2-ethylhexanoate was added. The mixture was kept at 110 ° C. with stirring for 2 hours. Acryl polyols A to E were obtained.

TABLE 1

Preparation Example 6

Polyester polyol resin

A reaction vessel equipped with a heater, a stirrer, a reflux condenser, a water separator, a distillation column, and a thermometer was charged with 36.2 parts of dimethylphthalate, 20.1 parts of neopentyl glycol, and 22.8 parts of 1,6-hexanediol. When the mixture was melted and stirred by application of heat, the reaction was carried out by raising the temperature to 210 ° C. at a constant rate over 4 hours in the presence of 0.02 parts of dibutyltin oxide. During this time the methanol produced by the transesterification reaction was removed from the reaction system. After cooling to 100 ° C, 31.0 parts of isophthalic acid and 4.2 parts of ε-caprolactone (PLACCEL M, manufactured by Daicel Chemical Industries) were added to the reaction vessel, and the mixture was then heated to 250 ° C. During this time, the temperature was raised from 180 ° C. to 250 ° C. over a period of 4 hours while removing the water produced by the condensation reaction. After maintaining the temperature at 250 ° C. for 1 hour, 5 parts of xylene was added until the acid value reached 1.0 to proceed with the reaction. After cooling to 100 ° C., the reaction mixture was diluted with 50 parts of Solvesso 150 and 50 parts of cyclohexanone. A polyester resin having a nonvolatile content of 50%, a hydroxyl value of 15 and a number average molecular weight of 8,000 was obtained.

Preparation Example 7

Modified silicone polyols

25 parts of xylene, 1.2 parts of maleic anhydride, 0.04 parts of dibutyltin oxide and Chemical Formula 5: in a reaction vessel equipped with a stirrer, a reflux condenser and heating means.

[Formula 5]

20 parts of polysiloxane were charged. After the mixture was heated at 90 ° C. for 1 hour, 35 parts of xylene and 20 parts of methyl isobutyl ketone (MIBK) were added thereto. After raising the internal temperature to 110 ° C., the following monomer mixture was added dropwise over 3 hours.

After addition, the reaction mixture was kept at 110 ° C. for 30 minutes, and then 0.5 part of t-butylperoxy-2-ethylhexaneoate was added thereto. The reaction mixture was then held at 110 ° C. for 2 hours. A modified silicone polyol having 55% volatile content, 85 hydroxyl value, and a number average molecular weight of 6,000 was obtained.

Preparation Example 8

Alkoxy silyl-containing acrylic resin

80 parts of xylene and 20 parts of n-butanol were charged to the same reaction container used in Preparation Example 7, and the mixture was heated to 110 ° C while stirring. The following mixture was added dropwise over 3 hours.

After addition the mixture was kept at 110 ° C. for 30 minutes and then 0.5 part of t-butylperoxy-2-ethylhexaneoate was added thereto. The mixture was then held at 110 ° C. for 2 hours. An alkoxysilyl-containing acrylic resin having a nonvolatile content of 50%, an alkoxysilyl equivalent weight of 623 and a number average molecular weight of 10,000 was obtained.

Preparation Example 9

Reactive Ultrafine Silica Particles

A 500 ml four-necked round flask equipped with a stirrer, a reflux condenser and a thermometer was charged with stirring 234 parts of tetramethoxysilane and 74 parts of methanol. Then, 22.2 parts of 0.05% hydrochloric acid was added and reacted at an internal temperature of 65 ° C. for 2 hours. After replacing the reflux condenser with a distillation column, the internal temperature was raised to 130 ℃ to remove methanol from the reaction system. A hydrolyzate / polycondensate having a hydrolysis rate of 40% and a number average molecular weight of 550 was obtained, hereinafter referred to as tetramethoxysilane oligomer. Oligomers having a degree of polymerization of 2 to 8 were detected here. The monomer content was 5%. The resulting oligomer was transferred to another flask heated to 130 ° C. and heated to 150 ° C. to remove monomer vapor by inert gas and then maintained at the same temperature for 3 hours. The monomer content was 0.2%. Thereafter, 30.77 parts of the oligomer obtained were mixed with 6.52 parts of chloride-free water, 0.31 part of aluminum tris-acetylacetonate and 62.4 parts of ethylene glycol monomethyl ether, and the mixture was left at room temperature for 1 day. A colorless, transparent and uniform suspension of the reactive ultrafine silica particles was obtained.

Example 1-11 and Comparative Example 1-8

Paint composition

According to the formulations shown in Tables 2 and 3, the pigments were ground with a sand grind mill together with the hydrolyzate / polycondensate (c) of the polyol resin (a) and the alkoxysilane until the particle size measured by the particle size gauge reached 5 μm. . Then, dibutyltin dilauric acid (0.1% by weight) of the total of the curing agent (b), the polyol resin (a) and the curing agent (b) was added and mixed with a disperser.

Painted Specimen

Board:

Zinc plated galvanized steel sheet with 0.4mm thickness.

primer:

A polyester primer (FLEKICOAT P600 primer, manufactured by Nippon Paint) was applied at a dry film thickness of 5 μm using a bar coater and baked at 220 ° C. (substrate temperature) for 1 minute.

Overcoating:

Each of the coating compositions was applied to the primer coating with a dry film thickness of 20 μm and baked at 220 ° C. (substrate temperature) for 1 minute.

Assessment Methods

Curability:

The coated substrate was rubbed by reciprocating 100 times with a load of 1 kg with gauze impregnated with xylene.

G (good): no change; F (normal): partially soluble; B (bad): The substrate is exposed.

Pollution Resistance:

The specimens were exposed to rain and washed for 3 months. The appearance after washing was visually observed.

G: clean; B: not clean

Hardness:

Pencil hardness according to JIS S-6006

Alkali Resistance:

The specimen was immersed in 5% NaOH for 12 hours at 20 ℃ and observed the appearance change of the membrane.

G: no change; F: bubbling; B: Molten

Acid Resistance:

The specimens were immersed in 5% HCl for 12 hours at 20 ℃ and observed the change in appearance of the membrane.

G: no change; F: bubbling; B: Molten

Moisture Stability:

20 g of the coating composition was placed in a bottle and exposed to an atmosphere of 70% relative humidity at 20 ° C. for 24 hours. Then a mixture of 10 g of xylene and 10 g of n-butanol was added to the bottle with stirring.

G: residue is dissolved; B: residues gelled

Membrane Formability:

The coating film as coated by the above method was visually observed.

G: Wrinkle free membrane; B: Wrinkles and cracks

material

Pigment:

TAIPAQUE CR97; Titanium oxide, manufactured by Ishihara Sangyo kaisha

Polyol Resin:

TA-22-293J; Polyester polyol resin having a hydroxyl value of 171, manufactured by Hitachi Chemical Polymer

ZEFFLE GK300; Fluororesin polyol having a hydroxyl value of 60, manufactured by Daikin Industries

Alkoxysilane Hydrolyzate / Polycondensate:

MKC silicate MS51; Tetramethoxysilane Hydrolyzate / Polycondensate with 52% SiO ₂ Content by Mitsubishi Chemical

MKC silicate MS56; Homogenous, but 56% SiO ₂ content.

Reactive ultrafine silica particles; See Preparation Example 9

Curing agent:

DESMODUR BL 3175; Methyl ethyl ketoxime block HMDI, manufactured by Sumitomo Bayer Urethane

CORONATE 2515; Lactamblock HMDI, manufactured by Nippon Polyurethane

DESMODUR BL 4165; Methyl ethyl ketoxime block IPDI, manufactured by Sumitomo Bayer Urethane

result

The evaluation results are shown in Tables 4 and 5.

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Examples 12-17 and Comparative Examples 9-13

The CATALYST 6000 brand name was added to replace the blocked polyisocyanate with melamine resin as the curing agent (b) and 1% by weight of the total of the polyol resin (a) and the curing agent (b) as solids in the organotin compound. The above examples and comparative examples were carried out in accordance with the formulations shown in Table 6, except that they were changed to dodecylbenzenesulfonic acid catalysts manufactured by Mitsui-Toatsu Chemicals. The hardener used was as follows:

CYMEL 238: alkyl etherified melamine resin (methoxy: i-butoxy = 60: 40), manufactured by Mitsui Cytech.

CYMEL 236: alkyl etherified melamine resin (methoxy: i-butoxy = 40: 60), manufactured by Mitsui Cytech.

CYMEL 235: alkyl etherified melamine resin (methoxy: i-butoxy = 60:40), manufactured by Mitsui Cytech.

The evaluation results are shown in Table 7.

TABLE 6

TABLE 7

Preparation Example 10

Surface treatment with silane coupling agent

20 parts of gamma-methacryloyloxypropyl trimethoxysilane (coupler A), 25 parts of gamma-glycidoxy propyl trimethoxysilane (coupler B), and 100 parts of silica particle suspensions of manufacture example 9 30 parts of oxysilane (coupler C) were added respectively. Each mixture was stirred and left at room temperature for 1 day.

Example 18-25 and Comparative Example 14-16

The above examples were carried out according to the formulations shown in Table 8 using the surface treated silica particles of Preparation Example 10. The obtained composition was further tested for storage stability according to the following method.

Storage stability:

The composition was stored at 40 ° C. for 1 month and the viscosity change was observed.

G: no increase in viscosity more than 1.2 times; F: increase by less than 2 times;

B: increased or gelled 2 times or more.

The evaluation results are shown in Table 9.

TABLE 8

TABLE 9

No content

Claims (18)

(a) a film-forming polyol resin having a hydroxyl value of 5 to 300 and a number average molecular weight of 500 to 20,000, (b) a curing agent reacting with the resin (a), (c) hydrolysates / polycondensates of tri or tetraalkoxysilanes having a hydrolysis / dealcoholization rate of less than 100%, and (d) A thermosetting resin composition comprising a catalyst for promoting a reaction between the resin (a) and the curing agent (b). The thermosetting resin composition according to claim 1, wherein the tri or tetraalkoxysilane has the following formula (3). [Formula 3] Wherein R ¹ is C ₁ -C ₆ alkyl, epoxy C ₁ -C ₆ alkyl, aryl or alkenyl, R ² is C ₁ -C ₆ alkyl, n is 0 or 1. The thermosetting resin composition according to claim 2, wherein the tetraalkoxysilane is tetramethoxysilane or tetraethoxysilane. The thermosetting resin composition according to claim 1, wherein the hydrolysis / dealcoholization rate is 30% to 60%. The thermosetting resin composition according to claim 1, wherein the resin (a) is an acrylic polyol resin, a polyester polyol resin, a fluorine-containing polyol resin, or a silicone polyol resin. The thermosetting resin composition according to claim 1, wherein the curing agent is a blocked polyisocyanate. The thermosetting resin composition according to claim 3, wherein the catalyst (d) is an organotin compound or a chelate of aluminum, titanium or zirconium. The thermosetting resin composition according to claim 1, wherein the curing agent is an aminoplast resin. The thermosetting resin composition according to claim 8, wherein the aminoplast resin is an alkyl etherified melamine resin. The thermosetting resin composition according to claim 8, wherein the catalyst is an organic sulfonic acid, an organic phosphoric acid, or an amine addition salt thereof. The thermosetting resin composition according to claim 1, wherein the hydrolyzate / polycondensate of the alkoxysilane is a suspension of reactive ultrafine silica particles having an inertia radius of 10 angstroms or less as measured by an incineration X-ray scattering method. The thermosetting resin composition according to claim 1, wherein the hydrolyzate / polycondensate of the alkoxysilane is surface treated with a silane coupling agent. 13. The thermosetting resin composition according to claim 12, wherein the molar ratio of the silane coupling agent to the sum of the silanol groups and alkoxysilyl groups present in the hydrolyzate / polycondensate of the alkoxysilane is 0.05 to 1. 13. The thermosetting resin composition according to claim 12, wherein the silane coupling agent has the following formula (4). [Formula 4] Wherein R ³ is γ-methacryloxypropyl, γ-glycidoxypropyl, methyl, ethyl, vinyl, phenyl, n-propyl, isobutyl, n-decyl, n-hexadecyl, trimethoxysilyl, γ- Dibutylaminopropyl or nonafluorobutylethyl, R ⁴ is C ₁ -C ₆ alkyl and m is 0, 1 or 2. The thermosetting resin composition according to claim 1, wherein the ratio of the hydrolyzate / polycondensate of the alkoxysilane is 1 to 300 parts by weight per 100 parts by weight of the total of the polyol resin (a) and the curing agent (b) as solid content. The thermosetting resin composition according to claim 15, wherein the ratio of the catalyst is 0.02 to 5 parts by weight based on 100 parts by weight of the total of the polyol resin (a) and the curing agent (b) as solid content. A thermosetting coating composition comprising the thermosetting resin composition of claim 1. A coating method of a metal substrate, comprising applying the coating composition of claim 17 to a metal substrate to form a film and then baking the film at an elevated temperature.