MXPA00006343A - Addition-crosslinkable epoxy-functional organopolysiloxane polymer and coating composition - Google Patents

Abstract

The present invention pertains to an epoxy-functional organopolysiloxane resin, and an epoxy-functional organopolysiloxane coating composition comprising the epoxy-functional organopolysiloxane resin. The epoxy-functional organopolysiloxane resin which contains repeating units having the formulae:wherein E is an epoxy-functional C1-18 hydrocarbon group containing one or more oxygen atoms, provided that no oxygen atom is directly bonded to a Si- atom;and R<1>and R<2>are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatom linking group, a is an integer of 0, 1, or 2, preferably 0 or 1;b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2;c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2;and in M units, a+b+c=3, in D units, a+b+c=2, in T units, a+b+c=1, with the proviso that the molecule, on average, contain at least two E components. The epoxy-functional organopolysiloxane coating composition comprises the epoxy-functional organopolysiloxane resin of the present invention and a hardener. Preferably, the hardener is an amine hardener. The epoxy-functional organopolysiloxane coating composition may optionally include pigments, a flow additive and a catalyst. The epoxy-functional organopolysiloxane resin is preferably prepared by reacting a silicone resin with a silane having at least one epoxy group per molecule. The coating composition cures through the crosslinking of the epoxy groups in the E group of the resin to provide a coating which is weather and corrosion resistant. The polysiloxane moieties in the resin render the cured coating resistant to U.V. light and heat.

Description

ORGANOPOLISILOXAN POLYMER AND COATING COMPOSITION WITH EPOXY FUNCTIONALITY RETICULABLES BY ADDITION TECHNICAL FIELD The present invention relates to an additive cross-linkable epoxy-functional organopolysiloxane polymer usable for manufacturing a coating composition having high weathering and chemical resistance, and more particularly, to a weather-resistant coating composition already the chemical products, which comprises an epoxidizable cross-linkable organopolysiloxane polymer by addition.

PREVIOUS TECHNIQUE Protective coatings used for industrial equipment, manufacturing facilities, oil drilling platforms and marine surface applications have to cope with exposure to corrosive environments and ultraviolet light (U.V.). These environments often cause damage to such coatings that may require frequent repainting of the underlying substrate. These protective coatings typically include a crosslinkable resin system, which acts as a binder, a hardener (i.e. a crosslinking agent), flowability additives and optional pigments. The crosslinkable resin system typically comprises a single resin, but may also comprise two or more resins. The resins that have been typically used for these applications are based on epoxy resins (aromatic and aliphatic), condensation curable polysiloxanes, silicone alkyd compounds, urethanes and silicone polyesters. Coatings based on aromatic epoxy resins provide acceptable results when resistance to chemical and corrosive environments is required. However, these coatings often fail when exposed to U.V. such as found in sunlight, and tend to swarm when used as a finishing coat in outdoor applications. Coatings based on aliphatic epoxy resins react relatively slowly, but are somewhat less sensitive to deterioration by U.V. than its aromatic counterparts. Urethane-based coatings have been used when the application requires corrosion resistance and weather resistance with an environmental curing response. However, these materials are considered toxic due to the possibility of very small amounts of free isocyanate present. In addition, said materials generally have a high content of volatile organic compounds (VOC's). Coatings based on alkyds of silicone have been used for applications that require a curing pattern in the conditions of the environment and resistance to high temperatures. Alkyd silicone compounds provide satisfactory resistance to U.V. light, and, since they contain between 20 and 30% (by weight) of silicone, they are also useful for resistance to elevated temperatures. However, in the presence of water and heat, the silicone alkyd polymer can decompose into its starting components. Once this occurs, the alkyd compound will continue to oxidize and form water-soluble polymers. Coatings based on silicone polyesters are used for oven-drying enamels, in which the resistance to high temperatures and to the weather is important, but they are also exposed to the same reversible reaction as the alkyd silicone compounds, which gives as a result the formation of polyester and silicone polymers. Recently, coatings formed by interpenetrating lattices (IPN) containing polysiloxanes have been used. These polysiloxanes utilize the alkoxy functionality in the silicone to crosslink, and often require a moisture cure mechanism and a high energy pre-hydrolysis step. These compositions may also require a high degree of alkoxy functionality in the silanes and polysiloxane components that, after curing, they will have a high VOC content due to the release of alcohol as a byproduct. Additionally, these coatings will tend to wrinkle if satisfactory curing is not achieved throughout the film, due to a continuation of curing after exposure to moisture and heat (sunlight). The byproducts are usually methanol, but in some cases butanol or propanol may be present. It would be desirable to provide a coating composition which is resistant to corrosion and also exhibits U.V. and the heat. It would also be desirable to provide a coating composition that can be used in formulations with low VOC content and can be formulated using solvents that are considered non-hazardous air pollutants. Additionally, it would be desirable to provide a coating composition whose crosslinking mechanism is primarily an addition reaction and which does not result in by-products or originates fewer by-products than would be found in cold-mixed silicone polymers.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to an organopolysiloxane polymer with epoxy functionality, and to a method of manufacturing thereof. The present invention also relates to an epoxy-functional organopolysiloxane coating composition comprising the epoxy-functional organopolysiloxane polymer, and a method of manufacturing the same. The organopolysiloxane polymer with epoxy functionality is preferably an organopolysiloxane resin with moderately crosslinked epoxy functionality and contains repeating units having the formulas: __- 0_? ¿.2_. O2 SiO ^ unit. _t in which E is a C1-18 hydrocarbon group with epoxy functionality containing one or more oxygen atoms, with the proviso that no oxygen atom is directly linked to an Si atom; and R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatomic linker group such as, but not limited to, 0 II -s -, -NH, - C- C -. - o- c- -o- s- or - o o o o O ll ll ll ll p - 0 - P - 0 O - S - O - NH - C NH - C - 0 - y - NH - C - NH a is an integer of 0, 1, or 2, preferably 0 or 1; b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; and in the units M, a + b + c = 3, in the units D, a + b + c = 2, in the units T, a + b + c = 1, with the proviso that the molecule contains, for on average, at least two components E. E is preferably a C2-15 hydrocarbon group with epoxy functionality, more preferably a C3-12 hydrocarbon group, and still more preferably a C3-6 hydrocarbon group. E is most preferably glycidoxypropyl (CH2- CHCH2OCH2CH2CH2) - Preferably, the groups R1 and R2 are individually C1-18 alkyl, C6-20 aryl, C7-18 alkylaryl, C7-18 arylalkyl, C5-12 cycloalkyl, C2-18 alkenyl, glycol, epoxy (with the proviso that the atom of oxygen is not directly bonded to a Si atom, C1-18 alkoxy, C2-20 unsaturated hydrocarbon groups such as vinyl, allyl, propenyl, isopropenyl and C4-18 alkenyl end groups, alkynyl, vinyl ether, and allyl ether . More preferably, R1 and R2 are independently methyl, ethyl, vinyl, allyl, methoxy, ethoxy, and phenyl groups. If T units are present, the molecule can contain or form silsesquisiloxanes, and polysilsesquioxanes from the T units. The coating composition is cured by crosslinking the epoxy groups in the E group of the resin to provide a coating that is resistant outdoors and chemical products. The polysiloxane residues of the resin make the cured coating resistant to light U.V. and the heat.

PREFERRED MODALITY OF THE INVENTION The coating composition of the present invention comprises a binder and a hardener. The coating composition may also comprise flowability additives, a crosslinking reaction catalyst for increasing the reaction rate, pigment for imparting color to the coating, wetting agents, surface modifiers, extenders and inerts, and other composition ingredients. commonly used siding. Preferably, the coating composition comprises about 10 to about 90 weight percent binder, based on the total weight of the coating composition. More preferably, the coating composition comprises about 25 to about 50 weight percent binder, based on the total weight of the coating composition. The binder preferably comprises at least about 80 weight percent solids, based on the weight of the binder, and more preferably at least about 90 weight percent solids. The binder preferably comprises an organopolysiloxane resin with additive, crosslinkable epoxide functionality and moderately crosslinked, containing repeating units having the formulas: Ea Rt, ftc SiO units M EaH ^, R ^ Si01, units £ Ea RfoJ £ c SiO ~ units S? OA units 2 wherein E is a C1-18 hydrocarbon group with epoxy functionality containing one or more oxygen atoms, with the proviso that no oxygen atom is directly bonded to an Si atom; and R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatomic linker group such as, but not limited to, o o o o o II II II II II-P- O O- S- O NH-C NH-C-O and NH-C-NH O a is an integer of 0, 1, or 2, preferably 0 or 1; b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; and in the units M, a + b + c = 3, in the units D, a + b + c = 2, in the units T, a + b + c = 1, with the proviso that the molecule contains, for on average, at least two components E. E is preferably a C2-15 hydrocarbon group with epoxy functionality, more preferably a C3-12 hydrocarbon group, and still more preferably a C3-6 hydrocarbon group. E is preferably glycidoxypropyl (CH2- CHCH20CH2CH, CH2 -).

Preferably, the groups R1 and R2 are individually C1-18 alkyl, C6-20 aryl, C7-18 alkylaryl, C7-18 arylalkyl, C5-12 cycloalkyl, C2-18 alkenyl, glycol, epoxy (with the proviso that the atom of oxygen is not directly bonded to a Si atom), C1-18 alkoxy, C2-20 unsaturated hydrocarbon groups such as vinyl, allyl, propenyl, isopropenyl and C4-18 alkenyl end groups, alkynyl, vinyl ether, and allyl ether.

More preferably, R1 and R2 are independently methyl, ethyl, vinyl, allyl, methoxy, ethoxy, and phenyl groups. If T units are present, the molecule can contain or form silsesquisiloxanes, and polysilsesquioxanes from the T units. The organopolysiloxanes can be terminated with conventional end groups, such as trialkylsilyl, dialkylsilylalolyl, dialkyl-alkoxysilyl, alkyldialkoxysilyl, dialkylvinyl-silyl, and analogues The organopolysiloxane resin with epoxy functionality preferably comprises less than about 15 mole percent Q units, between about 30 and about 100 mole percent T units, less than about 40 mole percent M units, and less than about 40 mole percent D units, based on the total number of moles of the epoxy-functional organopolysiloxane resin. More preferably, the epoxy-functional organopolysiloxane resin comprises less than about 10 mole percent Q units, between about 45 and about 80 mole percent T units, less than about 15 mole percent M units. , and less than about 15 mole percent D units, based on the total number of moles of the organopolysiloxane resin with epoxy functionality. Most preferably, the epoxy-functional organopolysiloxane resin comprises about 70 mole percent T units and about 30 mole percent D units, based on the total number of moles of the epoxy-functional organopolysiloxane resin. Preferably, the epoxy-functional organopolysiloxane resin has an alkoxy content of less than about 20 weight percent, based on the weight of the organopolysiloxane resin with epoxy functionality, more preferably less than about 18 weight percent, and most preferably about 15 percent by weight, or less than said proportion. The organopolysiloxane resin with epoxy functionality is preferably a liquid having a molecular weight of about 500 to about 5,000, more preferably about 750 to about 5,000, and most preferably about 1200. The viscosity of the organopolysiloxane resin with functionality Epoxy is preferably comprised between about 200 and 70,000 cps, the most preferred range being 13,000-20,000 cps. In a less preferred embodiment, the epoxy-functional organopolysiloxane resin is a solid and has a molecular weight of less than about 25,000, more preferably less than about 20,000, and most preferably less than about 15,000. When the epoxy-functional organopolysiloxane resin is a solid, the resin is dissolved in a suitable solvent, such as xylene, toluene, and another aromatic solvent, ketone and ester suitable for the manufacture of appropriate coating compositions.

While the epoxy-functional organopolysiloxane resin should have at least two epoxy groups per molecule, preferably the epoxy-functional organopolysiloxane resin has three or four epoxy groups per molecule. More preferably, the epoxy equivalent weight of the epoxy-functional organopolysiloxane resin is in the range of about 150-1000, with the preferred range being about 200-600. The epoxy-functional organopolysiloxane resin of the present invention can be represented by the formula: wherein R3 may be composed of (C1-C18) alkylene groups, optionally interspersed with oxygen (with the proviso that oxygen is not bound to the Si- group) and arylene; R4 can be independently selected from one of the following groups: alkyl, aryl, vinyl, glycol, (C1-C8) alkoxy, and epoxy (with the proviso that oxygen is not bound to the Si- group); n being greater than or equal to 1. The epoxy-functional organopolysiloxane resin of the present invention can be prepared by any known method and is preferably prepared by reaction of an epoxy-functional silane (i.e., a silane having at least at least one epoxy group per molecule) with a silicone polymer.

Suitable silicone polymers include units M, D, T, and Q, as are known in the art, and preferably have a molecular weight (MW) of from about 300 to about 15,000, more preferably from about 1000 to 2500, and most preferably from about 1000 to about 2000. Preferably, the silicone has an alkoxy equivalent weight of from about 150 to about 800, more preferably from about 200 to about 600. Suitable epoxy functionality silanes are represented by the formula: R5 R 5 - S 'i- R 53- wherein the R5 groups are one of, or a combination of, the following groups: (C1-12) alkyl, (C6-9) aryl, vinyl, glycol, (C1-12) alkoxy, and a C1- hydrocarbon group 18 with epoxy functionality of the formula R6-E1 in which E1 comprises an epoxy group and R6 comprises a C1-18 hydrocarbon group, with the proviso that at least one group R5 comprises R6-E1. It should be noted that the hydrocarbon group R6 can optionally be interspersed with at least one heteroatomic linker group such as, but not limited to -O-, -S-, and -NH-, with the proviso that no heteroatomic linker group is adjacent. to group E1.

Preferably, R6 comprises a C3-12 hydrocarbon group, and most preferably a C3-6 hydrocarbon group. Preferably, R6-E1 is glycidoxypropyl (C / H2 ° -xCHCH2OCH2CH2CH2-).

Preferably, the silane has a molecular weight of from about 100 to about 750, more preferably from about 150 to about 500, and most preferably from about 180 to about 350. The silane preferably has an epoxy functionality of about 1. to about 10, more preferably 1 to about 5, and most preferably about 1. The silane has an alkoxy functionality of from about 1 to about 10, more preferably 1 to about 5, and most preferably about 3. The types of silanes used will determine the final application.

Preferably, the silane is a β-glycidoxypropyl silane having C1-18 alkoxy groups. A preferred silane is β-glycidoxypropyltrimethoxysilane (OSi, A187). Most preferably, the silane is β-glycidoxypropyltriethoxysilane (Wacker GF-82). The use of β-glycidoxypropyltriethoxysilane will incorporate epoxy functionality covalently bound without having a hydrolysable Si-OC bond. The addition of silanes or polysiloxanes containing alkyl, aryl, or glycol substituents will increase the compatibility and the high temperature resistance of the polymer.

The reaction of the silicone polymer and the silane with epoxy functionality is a condensation reaction, and takes place in water as is known in the art. Preferably, a sufficient amount of water is provided to result in the epoxy-functional organopolysiloxane resin having an alkoxy content of less than about 20 weight percent, more preferably less than about 15 weight percent, and very preferably about 10 weight percent or less of said proportion. While the binder may comprise 100 percent of the organopolysiloxane resin with epoxy functionality, the binder preferably includes acrylic resin to reduce the unit cost of the binder. Preferably, the epoxy-functional polysiloxane resin is present in the binder in an amount of about 5 to about 75 weight percent of the total weight of the binder. More preferably, about 10 to about 25 weight percent, and most preferably about 15 weight percent. Preferably, the acrylic resin is present in the binder in an amount of about 25 to about 95 percent by weight of the total weight of the binder, more preferably about 75 to about 90 percent by weight, and most preferably about 85 weight percent. The acrylic resin may include, but is not limited to, those resins produced from one or more monomers such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, and n-butyl methacrylate. Such materials can be used separately or as mixtures of polymers. A particularly preferred acrylic resin is B44, by Rohm and Haas. The acrylic resin is preferably supplied in pellets and dissolved in the form of a solution before being mixed with the epoxy-functional siloxane resin. The acrylic resin can be cured by chain entanglement or coalescence, since it preferably does not have functional groups for crosslinking. The hardening component is preferably present in the coating composition of the present invention in an amount of about 2 to about 25 weight percent, based on the total weight of the coating composition. More preferably, the hardening component is present in the coating composition of the present invention in an amount of about 8 to about 17 weight percent, based on the total weight of the coating composition. Preferred hardeners include, but are not limited to, any one or a combination of the following: acids, for example phosphoric acid; amines such as aliphatic amines; adducts of aliphatic amines; polyamidoamines; Aminoaliphatic amines and adducts of aminaliphatic amines; aromatic amines; alkyl amines with at least one reactive hydrogen; Mannich bases; ketimines, and hydroxyl groups resulting from the reaction of the epoxy group with siloxane polymers; compounds containing mercapto groups and phosphorus groups. A preferred hardening component comprises a difunctional amine, ie, an amine having two active hydrogens, which may be substituted wholly or in part with an aminosilane having the general formula: Y-Si- (0-X) 3 where Y is H (HNR7) a, and in the case where "a" is equal to one, each R7 is a difunctional organic radical independently selected from the group consisting of aryl, alkyl, dialkylaryl, alkoxyalkyl, and cycloalkyl radicals, and wherein R7 can be vary within each molecule Y. Each X may be the same or different, and is limited to alkyl, hydroxyalkyl, alkoxyalkyl and hydroxyalkoxyalkyl groups containing less than about six carbon atoms. At least about 0.5 to about 1, 2, and preferably about 0.7 equivalents of amine or about 0.05 to about 0.5, and preferably about 0.4 moles of aminosilane per equivalent of epoxy may be present in the hardener component. Preferred aminosilanes include, but are not limited to: aminoethylaminopropyltriethoxysilane, N-phenylaminopropyltrimethoxysilane, trimethoxysilylpropyl-diethylenetriamine, 3- (3-amnophenoxy) propyltrimethoxy-silane, aminoethylaminomethylphenyltrimethoxy-silane, 2-aminoethyl-3-aminopropyltris [2- ethyl hexoxijsilane, N-aminohexylaminopropyltrimethoxysilane and tris [amino-propyl] -tris [methoxy] -ethoxy-silane.

Other preferred aminosilanes are difunctional silanes including aminopropyltrimethoxysilane and aminopropyltriethoxysilane. A difunctional aminosilane is desirable, because it has been found that the combination of an aminosilane having a reactivity of two, ie, having only two amine hydrogens, reacts with the non-aromatic epoxy group, which also has a reactivity of two, to form a linear epoxy polymer exhibiting improved weather resistance. Such preferred amines and aminosilanes produce epoxy-polysiloxane compositions which, when applied as a coating for substrates, exhibit excellent weathering resistance in terms of both color and gloss retention. Specific examples of preferred aminosilanes include Wacker ADDID 900, ADDID 901, Dow 6020, OSi A1100, OSi A1110, OSi A1120, OSi A1130, OSi A1387, and Y9632. To increase the speed of the crosslinking reaction, a catalyst can be used. If a catalyst is used, it is preferably present in the coating composition in an amount of up to about 5 weight percent, based on the weight of the coating composition. Suitable catalysts are hydrochloric acid (HCl), sulfuric acid (H2SO4) and potassium hydroxide (KOH). Examples of other suitable catalysts include compounds containing aluminum, zinc, manganese, zirconium, titanium, cobalt, iron, lead and tin. Suitable catalysts may also include organic tin catalysts, dibutyl tin dilaurate, dibutyltin diacetate, organic titanates, sodium acetate, and amines, such as secondary or tertiary aliphatic polyamines including propylamine, ethylaminoethanol, triethanolamine, triethylamine, and methyldiethanolamine, which they can be used alone or in combination. The coating composition may also include flowability additives. Examples of suitable flowability additives include, but are not limited to, flowability additives of silicone, polyester and acrylics. If flowability additives are present, they may be present in the coating composition in an amount of less than about 8 weight percent, based on the total weight of the coating composition. More preferably, the flowability additives are present in the coating composition in an amount of less than about 5 weight percent, and most preferably about 3 weight percent, based on the total weight of the coating composition. . A preferred coating composition may comprise up to about 50 weight percent pigment and / or fine particle size inert material, based on the total weight of the coating composition. The use of more than 50 weight percent pigment ingredient and / or inert material of fine particle size can produce a composition that is too viscous for its application. Depending on the particular end use, a preferred coating composition may comprise about 20 weight percent inert material and / or pigment of fine particle size. The pigment and / or inert material ingredients useful in forming the composition are selected from a material of fine particle size, preferably having at least 90 weight percent greater than the size of the U.S. 325 mesh. Suitable pigments can be selected from organic and inorganic color pigments which may include titanium dioxide, carbon black, lamp black, zinc oxide, natural and synthetic iron oxides red, yellow, brown and black, yellow toluidine and benzidine, blue and green phthalocyanine, and carbazole violet, as well as extender pigments including ground and crystalline silica, barium sulfate, magnesium silicate, calcium silicate, mica, micaceous iron oxide, calcium carbonate, zinc dust, aluminum and aluminum silicate, gypsum, feldspar and the like. It should be understood that the amount of pigment that is used to form the composition is variable, depending on the particular application of the composition, and may be zero when a clear composition is desired. The pigment and / or inert material ingredient is typically added to the binder, and more preferably to the epoxy-functional organopolysiloxane resin portion of the binder, and dispersed with a Cowles mixer to a minimum Hegman 3 milling fineness, or alternatively It is milled in a ball mill or sand mill to the same grinding fineness. The selection of a pigment or inert material of fine particle size and dispersion or milling to approximately Hegman 3 milling grade allows the atomization of the resin and curing components mixed with a conventional spray equipment, and provides a surface appearance Smooth and uniform after application. The coating compositions of the present invention generally have a sufficiently low viscosity that they can be applied by spraying, if desired, without the addition of a solvent. However, organic solvents may be added to improve atomization and application with electrostatic spraying equipment or to improve flowability and leveling as well as appearance when applied by brush, roller, or standard pneumatic and non-pneumatic spraying equipment. Exemplary solvents useful for this purpose include esters, ethers, alcohols, ketones, glycols and the like. If desired, up to about 50 weight percent solvent may be present in the coating composition, based on the total weight of the coating composition. Preferably, an amount in the range of about 10 to 20 weight percent organic solvent is used to conform to government regulations that control the proportion of volatile organic compound emissions. The coating compositions of the present invention may also contain other rheology modifiers, plasticizers, antifoaming agents, thixotropic agents, pigment wetting agents, bituminous and asphaltic spreaders, anti-settling agents, thinners, UV stabilizers, air removal agents and adjuvants of dispersion. The coating compositions of the present invention are supplied as a two pack system in water repellent containers. A package contains the binder, any pigment and / or inert material, additives and solvent if desired. The second package contains the hardener and any optional accelerating catalysts or agents. The coating composition can be applied by conventional application techniques, such as by brush, roller or spray. The compositions are intended to be used as protective coatings for steel, galvanized sheet, aluminum, concrete and other substrates with dry film thicknesses in the range of 25 microns to about two millimeters. The coating compositions of the present invention can be applied and completely cured at room temperature in the range from about -6 ° C to 50 ° C. At temperatures below -18 ° C, curing delays noticeably. However, the compositions of the present invention can be applied at oven drying or curing temperatures up to 150 ° C to 200 ° C. The epoxy-functional organopolysiloxane resin of the present invention is cured to form a U.V. light resistant coating, heat and corrosion by crosslinking, at room temperature, through the epoxy groups by the following addition reaction: 2 R - CH - CH2 + H2Nu R8 - where R8 comprises the residue of the organopolysiloxane resin with epoxy functionality and H2Nu represents a nucleophile having 2 hydrogen atoms, and may consist of a combination of the following: amine, polyamidoamine, polyamide , alkylamine with at least two reactive hydrogens, aminosilane such as Wacker ADDID 900, ADDID 901, Dow Z-6020, OSi A1100, Osi A1110, OSi A1120, OSi A1130, OSi A1387, Y9632, and hydroxyl groups resulting from the group reaction Epoxy with the siloxane polymer, mercapto, and phosphorous compounds. The reaction of the nucleophile with the epoxy component will form a covalent bond. This formation of covalent bonds will continue until all the reactive groups have been exhausted or the molecular weight of the polymer has increased to a point at which it is no longer movable. This will constitute the binder for the coating, and in this one pigments, extenders, inert components, wetting agents, surface modifiers and other components can be suspended, either in solution or in the form of a dry film. Since crosslinking occurs by addition, no by-product is formed, such as alcohol. The polysiloxane moieties, and in particular the Si-O bonds, in the organopolysiloxane resin make the resulting coating resistant to light U.V. and the heat. The alkyl and aryl substituents of the organopolysiloxane resin provide satisfactory compatibility of the resin with the organic systems, as well as increased resistance to water and heat. The coating composition is cured by the crosslinking of the epoxy groups existing in the resin. Once this invention is generally described, further understanding can be obtained by reference to certain specific examples that are provided herein for purposes of illustration only, and should not be construed as limiting, unless otherwise specified.

EXAMPLES EXAMPLE 1 Resin formulation Methylphenyldimethoxysilane is mixed, in an amount of 60.90 grams, with 167.43 grams of phenyltrimethoxysilane, 21.67 grams of dimethyldimethoxysilane, and 24.88 grams of deionized water in a three-necked round bottom flask, and mixed until homogeneous. . 1.37 grams of a 19% solution of KOH are added to the mixture. The mixture is heated to 80 ° C and maintained until 79.22 grams (101.5 ml) of alcohol is collected. 186.53 grams of α-glycidoxypropyltriethoxysilane and 17.13 grams of deionized water are incorporated into the above reaction product and mixed until homogeneous. The resulting mixture is heated to 80 ° C and refluxed until 70.19 grams (90.75 ml) of alcohol is collected. The final product is a yellow liquid with a viscosity that is approximately 18,590 cps using a Brookfield viscometer with a # 6 spindle at 20 rpm. The solids content of the solution is 93.11% by weight after the reaction of the residual alkoxy groups. The alkoxy content of the resin is about 13%. The equivalent weight of epoxy is approximately 492.

EXAMPLE 2 Resin formulation Same as Example 1. The polymer has a solids content of 93.09% by weight after the reaction of the residual alkoxy groups. The alkoxy content of the resin is about 13%. The epoxy equivalent weight is approximately 490.

EXAMPLE 3 Resin formulation Same as Example 2, with the addition of 7.02 grams of deionized water during the last step, collecting 19.84 g of alcohol after reflux. The alkoxy content of the resin is about 8%. The equivalent weight of epoxy is approximately 480.

EXAMPLE 1 Coating formulation The coating is made by mixing 145.0 grams of the silicone polymer of resin formulation example 2 with 145.0 grams of lanco pigment (Dupont R960) in a stainless steel container, and milling to a Hegman value of >; 7. 1.16 grams of ADDID® 160 (Wacker Silicones Corporation) are incorporated into the mixture. The epoxy-functional silicone is cured by mixing 23.56 grams of the aminosilane hardener ADDID® 900 (Wacker Silicones Corporation). The above formulation is applied to cold rolled steel sheets with a coiled wire rod, to a dry film thickness of 1, 1-2.5 mils (27.9-63.5 microns). The physical tests and the QUV resistance are determined after drying in the air for 24 hours.

EXAMPLE 2 Coating formulation Same as the coating formulation example 1, except that the resin formulation example 1 is replaced with the resin formulation example 2, and the amount of ADDID® 900 is reduced to 19.09 grams. The above formulations are applied to cold rolled steel plates using a wire rod wound with a dry film thickness of 1, 1-2.5 mils (27.9-63.5 microns). The physical tests and the QUV resistance are determined after drying in the air for 24 hours. EXAMPLE 3 Coating formulation 145.0 grams of the silicone polymer of resin formulation example 3 are mixed with 145.0 grams of white pigment (Dupont® 960) in a stainless steel vessel and grinding is effected to a Hegman value of > 7. 1.16 grams of ADDID® 160 (Wacker Silicones Corporation) are incorporated into the mixture. The epoxy-functional silicone is cured by mixing 23.56 grams of the aminosilane hardener ADDID® 900 (Wacker Silicones Corporation). The above formulations are applied to cold rolled steel plates using a wire rod wound with a dry film thickness of 1, 1-2.5 mils (27.9-63.5 microns). The physical tests and the QUV resistance are determined after drying in the air for 24 hours. The gloss was measured according to ASTM D 523-89 by quantification of the amount of light reflected by the film. The Delta E value was measured according to ASTM D 4587 by quantifying the degree of color change of the film after exposure to ultraviolet light for 872 hours. The gloss retention was measured according to ASTM D 4587 by comparing the amount of light reflected by the film after exposure to ultraviolet light for 872 hours with the amount of light reflected before exposure to ultraviolet light. The results of the tests of Examples 1-3 are shown below in Table 1: TABLE 1 Physical tests of the Examples 1 In accordance with ASTM D 523-89 2 In accordance with ASTM D 3363-74 3 In accordance with ASTM D 4752-87 4 In accordance with ASTM D 4587 5 Measured with an Elektro Physik apparatus The coating compositions of the present invention will have preferably a gloss, when measured according to ASTM D 523-89, of at least about 85, more preferably at least about 90, still more preferably at least about 95, and most preferably about 100. In addition , the coating compositions of the present invention will preferably have a pencil hardness, when measured according to ASTM D 3363-74, of at least about 6B, more preferably at least about B, even more preferably at least about HB, and most preferably at least about F. In addition, the coating compositions of the present invention will preferably have a Delta E value, is measured according to ASTM D 4587, less than about 3.0, more preferably less than about 2.0, and most preferably less than about 1.5. Also, the coating compositions of the present invention will preferably have a gloss retention, when measured according to ASTM D 4587, of at least about 85%, more preferably at least about 90%, and very well. preferable at least about 95%.

COMPARATIVE EXAMPLES COMPARATIVE EXAMPLE C1 Coating formulation Methylphenyldimethoxysilane is mixed in an amount of 108.13 grams with 234.77 grams of phenyltrimethoxysilane in a stainless steel vessel and mixed until homogeneous. 2.0 grams of hydrophilic combustion silica (Wacker HDK N20) and 120 grams of iron oxide (Miles 303T) are added to the mixture. The mixture is then ground to Hegman > 7.0. Then, 104.72 grams of methylphenyldimethoxysilane are mixed with 227.37 grams of phenyltrimethoxysilane and 108.9 grams of MICA 325, and the resulting mixture is mixed until homogeneous. Then 2.0 grams of a silicone additive (ADDID 170) and 27.00 grams of tetrabutyl titanate (TYZOR TBT-Dupont) are added. The above formulation is applied to cold rolled steel plates using a wire rod wound to a dry film thickness of 1, 1-2.5 mils (27.9-63.5 microns). The physical tests and the QUV resistance are determined after drying in the air for 24 hours.

COMPARATIVE EXAMPLE C2 Coating formulation Methylphenyldimethoxysilane, in an amount of 81.10 grams, is mixed with 227.51 grams of phenyltrimethoxysilane, and 34.28 grams of dimethyldimethoxysilane in a stainless steel vessel, and mixed until homogeneous. 2.0 grams of hydrophilic combustion silica (Wacker HDK N20) and 120 grams of iron oxide (Miles 303T) are added to the mixture. The mixture is then ground to Hegman > 7.0. 78.62 grams of methylphenyldimethoxysilane are then mixed with 220.65 grams of phenyltrimethoxysilane, 33.45 grams of dimethyldimethoxysilane and 108.9 grams of MICA 325. The resulting mixture is then mixed until homogeneous. Then 2.0 grams of a silicone additive (ADDID 170) and 27.00 grams of tetrabutyl titanate (TYZOR TBT-Dupont) are added. The above formulation is applied to cold rolled steel plates using a wire rod wound to a dry film thickness of 1, 1-2.5 mils (27.9-63.5 microns). The physical tests and the QUV resistance are determined after drying in the air for 24 hours.

COMPARATIVE EXAMPLE C3 Coating formulation 342.90 grams of a 50% solution of an acrylic material (Rohm and Haas B44) are mixed with 2.0 grams of hydrophilic combustion silica (Wacker HDK N20) and 120 grams of iron oxide (Miles 303T) in a stainless steel container and mix until homogeneous. The mixture is then ground to Hegman > 7.0. 602.10 grams of the same 50% solution of acrylic material (Rohm and Haas B44) of the previous paragraph are then mixed with 108.9 grams of MICA 325, and the resulting mixture is then mixed until homogeneous. Then 2.0 grams of silicone additive (ADDID) are added 170), the resulting mixture being mixed for an additional 15 minutes. The above formulations are applied to cold rolled steel plates using a wire rod wound to a dry film thickness of 1, 1-2.5 mils (27.9-63.5 microns). The physical tests and the QUV resistance are determined after drying in the air for 24 hours. The results of the tests of Comparative Examples C1-C3 are shown below in Table 2: TABLE 2 Physical tests of the Comparative Examples 1 In accordance with ASTM D 523-89 2 In accordance with ASTM D 3363-74 3 In accordance with ASTM D 4752-87 4 In accordance with ASTM D 4587 5 Measured with an Elektro Physik apparatus While embodiments of the invention have been illustrated and described. the invention, it should not be understood that these embodiments illustrate and describe all possible forms of the invention. Rather, the terms used in the specification are terms of description and not limitation, and it is understood that various changes can be made without departing from the spirit and scope of the invention.

Claims (34)

NOVELTY OF THE INVENTION CLAIMS

1. - An organopolysiloxane resin with epoxy functionality containing repetitive units having the formulas: TheJR R.}. YES-i units M EaR R SÍO-, units D 'a ^ b ^ «S7 ^ 3 units T

2 Q 2 units in which E is a C1-18 hydrocarbon group with epoxy functionality containing one or more oxygen atoms, with the proviso that no oxygen atom is directly bonded to an Si atom; and R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatomic linker group such as, but not limited to, O o or II II II -NH- -c-c -o- C- -o- - o. -C-P- O, O- S- O -NH- C NH-C- O and NH-C-NH. a is an integer of 0, 1, or 2, preferably 0 or 1; b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; and in the units M, a + b + c = 3, in the units D, a + b + c = 2, in the units T, a + b + c = 1, in which the M units are present in less of about 40% in moles; the D units are present in less than about 40 mole%; and the molecule contains, on average, at least two E. components. The resin of claim 1, wherein the hydrocarbon group of E comprises a C3-12 hydrocarbon group.

3. The resin of claim 1, wherein the epoxy-functional organopolysiloxane resin has an alkoxy content of less than about 20% by weight, based on the weight of the organopolysiloxane resin with epoxy functionality.

4. The resin of claim 1, wherein the epoxy-functional organopolysiloxane resin has an epoxy equivalent weight in the range of about 150-1000.

5. The resin of claim 2, wherein the epoxy-functional organopolysiloxane resin has an epoxy equivalent weight in the range of about 200-600.

6. The resin of claim 1, wherein the epoxy-functional organopolysiloxane resin has a viscosity in the range of about 200-70,000 cps.

7. The resin of claim 2, wherein the group E is glycidoxypropyl

8. - The resin of claim 6, wherein the epoxy-functional organopolysiloxane resin comprises T units, and the T units include structures selected from the group consisting of silsesquioxane and polysilsesquioxane structures.

9. The resin of claim 1, wherein the resin has a molecular weight between about 750 and 25,000.

10. The resin of claim 1, wherein the epoxy-functional organopolysiloxane resin is prepared by reacting a silicone resin with a silane having at least one epoxy group per molecule.

11. The resin of claim 10, wherein the silane is represented by the formula: 5 '5 -R - Si - R i? wherein the R5 groups are one of, or a combination of, the following groups: (C1-12) alkyl, (C6-9) aryl, vinyl, glycol, (C1-12) alkoxy, and a C1- hydrocarbon group 18 with epoxy functionality of the formula R6-E1 in which E1 comprises an epoxy group and R6 comprises a C1-18 hydrocarbon group optionally interspersed with at least one heteroatom linker group, with the proviso that at least one group R5 comprises R6- E1.

12. - The resin of claim 11, wherein the heteroatomic linker group, if present, is not adjacent to the E1 group.

13. The resin of claim 11, wherein the hydrocarbon group of R6 comprises a C3-12 hydrocarbon group.

14. The resin of claim 11, wherein the silane has a molecular weight in the range of about 100 to about 750.

15. The resin of claim 14, wherein the silane has an epoxy functionality comprised in the range of about 1 to about 10.

16. The resin of claim 15, wherein the silane has an alkoxy functionality in the range of about 1 to about 10.

17. The resin of claim 13, wherein R6-E1 is glycidoxypropyl (CH2- CHCH2OCH2CH2CH2) •

18. - The resin of claim 11, wherein the silane is a β-glycidoxypropyl silane having C1-18 alkoxy groups.

19. The resin of claim 10, wherein the silicone has a molecular weight in the range of about 300 to about 15,000.

20. - An organopolysiloxane coating composition with epoxy functionality comprising: a hardener; and an epoxy-functional organopolysiloxane resin containing repeating units having the formulas: EaR¿R SiOl M units EaR¡, R ^ YES? 2 units EaRfr c StO ~ units SiO units Q wherein E is a C1-18 hydrocarbon group with epoxy functionality containing one or more oxygen atoms, with the proviso that no oxygen atom is directly linked to an Si atom; and R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatomic linker group such as, but not limited to, o o o __ 0 ll_ _ ll_ _ II or p o o or II H II II II O- P- O O- S- O NH- C NH_ C_ O and NH-C-NH. or a is an integer of 0, 1, or 2, preferably 0 or 1; b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; and in the units M, a + b + c = 3, in the units D, a + b + c = 2, in the units T, a + b + c = 1, in which the M units are present in less of about 40% in moles; the D units are present in less than about 40 mole%; and with the proviso that the molecule contains, on average, at least two E components.

21. The coating composition of claim 20, wherein the hardener is an aminic hardener.

22. The coating composition of claim 20, wherein the hydrocarbon group of E comprises a hydrocarbon group C3-12.

23. The coating composition of claim 20, wherein the epoxy-functional organopolysiloxane resin has an alkoxy content of less than about 20% by weight, based on the weight of the organopolysiloxane resin with epoxy functionality.

24. The coating composition of claim 20, wherein the epoxy-functional organopolysiloxane has an epoxy equivalent weight in the range of about 200-600.

The coating composition of claim 20, comprising additionally an acrylic resin.

26. The coating composition of claim 20, wherein the epoxy-functional organopolysiloxane resin is prepared by reacting a silicone resin with a silane having at least one epoxy group per molecule.

27. - The coating composition of claim 26, wherein the silane is represented by the formula: R5 5 '.. R - Si - RJ 5 R3 in which the groups R5 are one of, or a combination of, the following groups: (C1-12) alkyl, (C6-9) aryl, vinyl, glycol, alkoxy (C1-12), and a C1-18 hydrocarbon group with epoxy functionality of the formula R6-E1 in which E1 comprises an epoxy group and R6 comprises a C1-18 hydrocarbon group optionally interspersed with at least one heteroatom linker group, with the condition that at least one group R5 comprises R6-E1.

28. The coating composition of claim 27, wherein R6-E1 is glycidoxypropyl.

29. The coating composition of claim 20, further comprising a fluidity additive. (C AH2- CHCH2OCH2CH2CH2-).

30. - An organopolysiloxane coating composition with epoxy functionality, the coating composition comprising a hardener and an organopolysiloxane resin with epoxy functionality prepared by reaction of a silane having epoxy functionality with a silicone resin, the epoxy-functional silane being provided and the silicone resin in effective amounts such that the epoxy-functional organopolysiloxane coating composition is sufficiently flexible to adhere to a metal sheet without cracking the sheet after being subjected to the QUV B test of 872 hours in accordance with ASTM D 4587.

31.- The epoxy-functional organopolysiloxane coating composition of claim 30., wherein the coating composition has a gloss retention of at least about 85% after subjecting it to the QUV B test of 872 hours in accordance with ASTM D 4587.

32.- The epoxy-functional organopolysiloxane coating composition of claim 31, wherein the coating composition has a Delta E value less than at least approximately 3.0 after subjecting it to the 872 hour QUV B test in accordance with ASTM D 4587.

33.- The epoxy-functional organopolysiloxane coating composition of claim 32, wherein the epoxy-functional resin contains repeating units having The formulas: Ea R RSSlO t un idades D units Ea RlR St? 3 units T Q 2 units in which E is a C1-18 hydrocarbon group with epoxy functionality containing one or more oxygen atoms, with the proviso that no oxygen atom is directly bonded to an Si atom; and R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatomic linker group such as, but not limited to, 0 0 or II II II - NH- C- 0- 0- C- 0- or- s- 0 0 0 0 0 II II II II - 0- P- or- II o- s- or -. - - NH-C NH-C- - 0 - and - NH - C - NH II or a is an integer of 0, 1, or 2, preferably 0 or 1; b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2, c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; and in the units M, a + b + c = 3, in the units D, a + b + c = 2, in the units T, a + b + c = 1, in which the M units are present in less of about 40% in moles; the D units are present in less than about 40 mole%; and with the proviso that the molecule contains, on average, at least two components E.

34. - The epoxy-functional organopolysiloxane coating composition of claim 33, wherein the silane is represented by the formula: R5 5 l 5- R -Si-R ' wherein the R5 groups are one of, or a combination of, the following groups: (C1-12) alkyl, (C6-9) aryl, vinyl, glycol, (C1-12) alkoxy, and a C1- hydrocarbon group 18 with epoxy functionality of the formula R6-E1 in which E1 comprises an epoxy group and R6 comprises a C1-18 hydrocarbon group optionally interspersed with at least one heteroatom linker group, with the proviso that at least one group R5 comprises R6- E1. SUMMARY OF THE INVENTION The present invention relates to an epoxy-functional organopolysiloxane resin, and an epoxy-functional organopolysiloxane coating composition comprising the epoxy-functional organopolysiloxane resin; the organopolysiloxane resin with epoxy functionality contains repetitive units that have the formulas: M units EaR¡, R¿S02 units EaR¡, Rc Sl03 units T 2 SiO Q units in which E is a yiuμw ni.iu.ai uupau? pu M epoxy functionality containing one or more oxygen atoms, with the proviso that no oxygen atom is directly attached to an Si atom; and R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatom linker group, a is an integer of 0, 1, or 2, preferably 0 or 1; b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; c is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2; and in the units M, a + b + c = 3, in the units D, a + b + c = 2, in the units T, a + b + c = 1, with the proviso that the molecule contains, for medium term, at least two components E; the epoxy-functional organopolysiloxane coating composition comprises the epoxy-functional organopolysiloxane resin of the present invention and a hardener. Preferably, the hardener is an amine hardener. The organopolysiloxane coating composition with epoxy functionality can optionally include pigments, a flow additive and a catalyst; the organopolysiloxane resin with epoxy functionality is preferably prepared by reaction of a silicone resin with a silane having at least one epoxy group per molecule; the coating composition is cured by the crosslinking of the epoxy groups in group E of the resin to provide a coating which is resistant to weathering and corrosion; the polysiloxane residues in the resin make the cured coating resistant to U.V. and the heat. WACKER / mmr * P00 / 729 = ^ a i ^ = ¿_