Silicone-modified epoxy resin, coating composition, and article coated with said coating composition

Abstract

Provided are a silicone-modified epoxy resin and a coating composition containing said resin, from which a cured product exhibiting high heat resistance can be obtained. Specifically provided is a silicone-modified epoxy resin having an epoxy equivalent weight in the range of 1,000-3,000 g / equivalent weight, and having an alkyl group with 10 or more carbon atoms.

Description

[Technical field]

[0001] The present invention relates to a silicone-modified epoxy resin, a coating composition, and an article coated with the coating composition. [Background technology]

[0002] A method of providing heat resistance and corrosion resistance (weather resistance) to industrial metal components such as steel plates for automobiles, steel pipes for gas pipelines, and metal building materials, as well as household metal components such as frying pans and barbecue grills, is to apply a protective resin coating to the surface of the metal components.

[0003] In particular, motorcycle mufflers and steel pipes for gas pipelines, which require high heat resistance and corrosion resistance, are generally coated with epoxy resin for protection.

[0004] As the above-mentioned epoxy resin, silicone-modified epoxy resins modified with silicone are known (for example, Patent Document 1). The silicone-modified epoxy resins have enhanced heat resistance by introducing siloxane bonds, which have high bond strength, into the epoxy resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2020-521020 Summary of the Invention [Problem to be solved by the invention]

[0006] The epoxy resin in Patent Document 1 is a silicone-modified epoxy resin obtained by modifying an epoxy resin with a reactive organosilane, but its heat resistance does not reach 500° C., and its performance cannot be said to be sufficient.

[0007] To increase the heat resistance of the epoxy resin itself, it is sufficient to make it highly cross-linked, but increasing the epoxy equivalent to achieve high cross-linking also increases the viscosity, which poses the problem of significantly reducing compatibility with pigments that impart various functions to the coating, such as extender pigments and anti-rust pigments. If compatibility between the epoxy resin and the pigment cannot be guaranteed, voids will form in the resulting coating, compromising the heat resistance of the coating. For this reason, there is naturally an upper limit to the epoxy equivalent of epoxy resins for coating.

[0008] An object of the present invention is to provide a silicone-modified epoxy resin which can produce a cured product exhibiting high heat resistance, and a coating composition containing said resin. [Means for solving the problem]

[0009] Means for Solving the Problems The present inventors conducted extensive research to solve the above problems and discovered that by introducing an alkyl group having 10 or more carbon atoms into a silicone-modified epoxy resin, it is possible to suppress an increase in viscosity and ensure compatibility with pigments, thereby completing the present invention.

[0010] That is, the present invention relates to the following silicone-modified epoxy resins, etc. 1. Silicone-modified epoxy resin with an epoxy equivalent in the range of 1,000 to 3,000 g / equivalent and an alkyl group with 10 or more carbon atoms. 2. A silicone-modified epoxy resin according to 1, having a bisphenol structure. 3. The silicone-modified epoxy resin according to 1 or 2, having an acid value in the range of 1 to 10 mgKOH / g. 4. The silicone-modified epoxy resin according to any one of 1 to 3, which comprises, as reaction components, an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid. 5. The silicone-modified epoxy resin according to 4, wherein the epoxy resin having a hydroxyl group is a bisphenol-type epoxy resin having a hydroxyl group. 6. The silicone compound having a silanol group is R 3 SiO1 / 2 Unit (M unit), SiO 4 / 2 Unit (Q unit), R 2 SiO 2 / 2 Units (D units) and RSiO 3 / 2 6. The silicone-modified epoxy resin according to 4 or 5, which is a silicone compound having one or more siloxy units selected from units (T units) (R is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyl group), has two or more silanol groups, and the proportion of phenyl groups in R in the siloxy units is 50 mol % or more. 7. The silicone modified epoxy resin according to any one of 4 to 6, wherein the fatty acid is a saturated fatty acid having 11 to 22 carbon atoms. 8. The silicone-modified epoxy resin according to any one of 4 to 7, wherein, in the reaction components, the epoxy resin is in the range of 30 to 60 parts by mass, the silicone compound having a silanol group is in the range of 20 to 50 parts by mass, and the fatty acid is in the range of 1 to 5 parts by mass. 9. A coating composition comprising the silicone-modified epoxy resin according to any one of 1 to 8 and a pigment. A cured product of the coating composition described in 10.9. An article coated with the cured coating composition described in 11.9. A metal member coated with a cured product of the coating composition described in 12.9. Effect of the Invention

[0011] The present invention provides a silicone-modified epoxy resin that exhibits high heat resistance. The present invention can provide a coating composition that can provide a coating exhibiting high heat resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described below. The present invention is not limited to the following embodiment, and can be implemented by making appropriate modifications within the scope that does not impair the effects of the present invention. The compounds in the present specification may be derived from fossil resources or biological resources.

[0013] [Silicone modified epoxy resin] The silicone-modified epoxy resin of the present invention has an epoxy equivalent in the range of 1,000 to 3,000 g / equivalent and has an alkyl group having 10 or more carbon atoms. In the silicone modified epoxy resin of the present invention, despite its high epoxy equivalent, the introduction of an alkyl group having 10 or more carbon atoms can suppress high viscosity. Furthermore, the introduction of an alkyl group having 10 or more carbon atoms can ensure compatibility with pigments, which will be described later.

[0014] In the present invention, "having an alkyl group having 10 or more carbon atoms" means that the silicone-modified epoxy resin has at least one alkyl group having 10 or more carbon atoms. In the present invention, at least one of the terminal epoxy groups of the silicone-modified epoxy resin is preferably substituted with an alkyl group having 10 or more carbon atoms. That is, the silicone-modified epoxy resin of the present invention preferably has an alkyl group having 10 or more carbon atoms at at least one terminal.

[0015] The alkyl group having 10 or more carbon atoms contained in the silicone modified epoxy resin of the present invention is preferably an alkyl group having 12 to 22 carbon atoms, and more preferably an alkyl group having 12 to 18 carbon atoms. The alkyl group having 10 or more carbon atoms contained in the silicone-modified epoxy resin of the present invention may be either a branched alkyl group or a linear alkyl group, but is preferably a linear alkyl group.

[0016] The silicone modified epoxy resin of the present invention may have an epoxy equivalent in the range of 1,000 to 3,000 g / equivalent, preferably in the range of 1,000 to 2,500 g / equivalent, and more preferably in the range of 1,000 to 2,200 g / equivalent. The epoxy equivalent of the silicone-modified epoxy resin of the present invention is evaluated by the method described in the Examples.

[0017] The acid value of the silicone-modified epoxy resin of the present invention is, for example, in the range of 1 to 10 mgKOH / g, preferably in the range of 1 to 8 mgKOH / g, more preferably in the range of 1 to 7 mgKOH / g, and even more preferably in the range of 1 to 6 mgKOH / g. The acid value of the silicone-modified epoxy resin of the present invention is evaluated by the method described in the Examples.

[0018] The number average molecular weight of the silicone modified epoxy resin of the present invention is not particularly limited, but is, for example, in the range of 500 to 10,000, preferably in the range of 1,000 to 8,000, and more preferably in the range of 1,000 to 6,000. The weight average molecular weight of the silicone modified epoxy resin of the present invention is not particularly limited, but is, for example, in the range of 10,000 to 50,000, and preferably in the range of 20,000 to 40,000. The number average molecular weight and weight average molecular weight of the silicone-modified epoxy resin of the present invention are evaluated by the method described in the Examples.

[0019] The silicone-modified epoxy resin of the present invention preferably comprises an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid as reaction components. The term "reactive components" as used herein refers to components that constitute the structure of the silicone-modified epoxy resin, and does not include solvents or catalysts that do not constitute the structure of the silicone-modified epoxy resin. Each component will be described below.

[0020] (Epoxy resin with hydroxyl groups) Epoxy resins are resins having at least one epoxy group in the molecule, and examples thereof include bisphenol type epoxy resins such as bisphenol A type, bisphenol F type, bisphenol E type, bisphenol B type, bisphenol S type, bisphenol AD ​​type, bisphenol AP type, and bisphenol BP type; novolac type epoxy resins such as phenol novolac type and cresol novolac type; resorcinol type epoxy resins; aromatic epoxy resins such as trisphenolmethane triglycidyl ether; naphthalene type epoxy resins; fluorene type epoxy resins; and biphenyl type epoxy resins. The epoxy resin having a hydroxyl group of the present invention is, for example, the above-mentioned epoxy resin, and further has a hydroxyl group.

[0021] The epoxy resin having a hydroxyl group is preferably a bisphenol A type epoxy resin having a hydroxyl group, and more preferably a compound represented by the following general formula (A-1).

[0022] [ka] (In the general formula (A-1), X is a bisphenol structure represented by the following general formula (A-2), n is the number of repetitions.)

[0023] [ka] (In the general formula (A-2), R 1 and R 2 each independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, n1 and n2 each independently represent an integer ranging from 0 to 4; L is a single bond, an alkylene group having 1 to 6 carbon atoms, an ether bond (-O-), a ketone bond (-C(=O)-), an ester bond (-C(=O)O-, a sulfide bond (-S-) or a sulfonyl bond (-SO 2 -) is.

[0024] In general formula (A-2), R 1 If there are multiple, multiple R 1 may be the same or different. Similarly, R 2 If there are multiple, multiple R 2 may be the same as or different from each other.

[0025] When the epoxy resin having a hydroxyl group is, for example, a compound represented by the above general formula (A-1), the epoxy group of the compound represented by general formula (A-1) reacts with a fatty acid to introduce an alkyl group at the terminal.

[0026] The epoxy equivalent of the hydroxyl group-containing epoxy resin is preferably in the range of 300 to 3,000 g / equivalent, more preferably in the range of 450 to 3,000 g / equivalent, and more preferably in the range of 600 to 3,000 g / equivalent. The epoxy equivalent is the weight of an epoxy resin required to obtain 1 mol of epoxy groups, and is measured by the method described in the examples.

[0027] In the present invention, the epoxy resin having a hydroxyl group is used so that its average epoxy equivalent falls within the range of 1,000 to 3,000 g / equivalent. For example, when two kinds of epoxy resins having a hydroxyl group are used, they are used so that their average epoxy equivalent calculated by (total weight of epoxy resins) / {(amount of epoxy resin 1 used / epoxy equivalent of epoxy resin 1)+(amount of epoxy resin 2 used / epoxy equivalent of epoxy resin 2)} falls within the range of 1,000 to 3,000.

[0028] The epoxy resin having a hydroxyl group may be a commercially available product, and examples of the commercially available product include EPICLON 1055, EPICLON 3040, EPICLON 3050, EPICLON 4050, EPICLON 7050 (all manufactured by DIC Corporation), LAPOX P-62, LAPOX P-5 (all manufactured by ATUL INDIA), E-20 (epoxy equivalent: 455 to 555 g / Eq), E-21 (epoxy equivalent: 480 to 580 g / Eq), E-42 (epoxy equivalent: 230 to 280 g / Eq), E-44 (epoxy equivalent: 210 to 240 g / Eq), and E-51 (epoxy equivalent: 184 to 194 g / Eq) (all manufactured by SINOPEC CORPORATION).

[0029] (Silicone compound having silanol groups) In the silicone compound having a silanol group, the silanol group reacts with a hydroxyl group of an epoxy resin, and thereby a crosslinked structure is formed that crosslinks epoxy resins together.

[0030] The silicone compound having a silanol group is preferably a silicone compound having two or more silanol groups, more preferably R 3 SiO 1 / 2 Unit (M unit), SiO 4 / 2 Unit (Q unit), R 2 SiO 2 / 2 Units (D units) and RSiO 3 / 2 It is a silicone compound having one or more siloxy units selected from units (T units) (R is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyl group) and having two or more silanol groups.

[0031] The silicone compound having a silanol group is R 3 SiO 1 / 2 Unit (M unit), SiO 4 / 2 Unit (Q unit), R 2 SiO 2 / 2 Units (D units) and RSiO 3 / 2In the case of a silicone compound having one or more siloxy units selected from units (T units) (R is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyl group) and having two or more silanol groups, the proportion of the phenyl groups in R in the siloxy units is preferably 50 mol % or more.

[0032] By making the ratio of phenyl groups in R in the siloxy unit 50 mol % or more, the heat resistance can be improved. The proportion of phenyl groups in the siloxy units can be confirmed by Fourier transform infrared spectroscopy (FTIR), and the upper limit of the proportion of phenyl groups in the siloxy units is, for example, 80 mol %.

[0033] As the silicone compound having a silanol group, a commercially available product can be used, and examples of the commercially available product include DOWSIL RSN-6018, DOWSIL RSN-0220, and DOWSIL 3040 (all manufactured by The Dow Chemical Company). The proportion of phenyl groups in R in the siloxy unit in the commercially available products is 73 mol % for DOWSIL RSN-6018, 67 mol % for DOWSIL RSN-0220, and 50 mol % for DOWSIL 3040.

[0034] (fatty acid) The fatty acid is preferably a saturated fatty acid having 11 to 22 carbon atoms, more preferably a straight-chain saturated fatty acid having 11 to 22 carbon atoms, and even more preferably a straight-chain saturated fatty acid having 11 to 18 carbon atoms.

[0035] The fatty acids may be used alone or in combination of two or more.

[0036] Specific examples of fatty acids include undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, heneicosylic acid, and behenic acid.

[0037] Oils containing fatty acids may also be used as reaction components. Examples of the fats and oils include hydrogenated coconut oil fatty acids, hydrogenated palm kernel oil fatty acids, hydrogenated palm oil fatty acids, hydrogenated olive oil fatty acids, hydrogenated castor oil fatty acids, hydrogenated rapeseed oil fatty acids, etc. These are obtained by hydrolyzing and hydrogenating oils obtained from coconut, palm kernel, palm, olive, castor, and rapeseed, respectively, and all of them are mixtures of two or more types of long-chain aliphatic monocarboxylic acids.

[0038] The silicone-modified epoxy resin of the present invention preferably contains as reaction components an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid, and may further contain components other than these as long as the effects of the present invention are not impaired. The silicone-modified epoxy resin of the present invention is preferably a reaction product of an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid.

[0039] The mixing ratio of the silicone compound having a silanol group is, for example, in the range of 50 to 100 parts by mass, preferably in the range of 60 to 90 parts by mass, and more preferably in the range of 70 to 85 parts by mass, per 100 parts by mass of the epoxy resin having a hydroxyl group.

[0040] The mixing ratio of the fatty acid is, for example, in the range of 1 to 10 parts by mass, preferably in the range of 1 to 7 parts by mass, more preferably in the range of 1 to 5 parts by mass, and even more preferably in the range of 3 to 4 parts by mass, relative to 100 parts by mass of the epoxy resin having a hydroxyl group.

[0041] The mixing ratio of each component in the reaction components is preferably in the range of 30 to 60 parts by mass of the epoxy resin having a hydroxyl group, 20 to 50 parts by mass of the silanol-modified silicone compound, and 1 to 5 parts by mass of the fatty acid.

[0042] The reaction of an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid can be carried out by a known method, and for example, the silicone-modified epoxy resin of the present invention can be prepared by heating a reaction system containing an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid. In addition, the silicone-modified epoxy resin of the present invention can also be prepared by reacting an epoxy resin having a hydroxyl group with a silicone compound having a silanol group to form a silicone-modified epoxy resin, and then reacting the silicone-modified epoxy resin with a fatty acid.

[0043] [Coating composition] The coating composition of the present invention contains the silicone-modified epoxy resin of the present invention and a pigment, and is used, for example, by dissolving it in a solvent.

[0044] Examples of the solvent for the coating composition of the present invention include alcohol solvents such as methanol, ethanol, propanol, n-butanol, iso-butanol, tert-butanol, and 3-methoxybutanol; glycol solvents such as ethylene glycol and propylene glycol; glycol ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol dimethyl ether; glycol ester solvents such as ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and tetrahydrofuran. The solvent may be used alone or in combination of two or more kinds.

[0045] In the coating composition of the present invention, the solvent is used so that the solid content concentration is, for example, 10 to 80 mass %, and preferably, the solid content concentration is 50 to 70 mass %.

[0046] The coating composition of the present invention can ensure sufficient pigment compatibility. Among the above pigments, there are, for example, those called "extender pigments" and those called "anti-rust pigments." Extender pigments are pigments that are blended with the resin composition for the purpose of modifying the composition (increasing the amount, coloring properties, drying properties, etc.), while anti-rust pigments are pigments that are blended with the resin composition to increase its corrosion resistance.

[0047] Specific examples of extender pigments include barium sulfate, barium carbonate, calcium carbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, barium titanate, calcium hydroxide, calcium sulfite, calcium sulfate, calcium oxide, calcium silicate, titanium oxide, silica, zeolite, and talc.

[0048] Specific examples of anti-rust pigments include phosphates, hydrogen phosphates, phosphosilicates, borosilicates, borates, metaborates, molybdates, chromates, polyphosphates, and the like, of one or more metals selected from the group consisting of calcium, strontium, barium, zinc, aluminum, and magnesium.

[0049] The coating composition of the present invention may contain at least one of an extender pigment and an anti-rust pigment. The coating composition may contain one kind of extender pigment or two or more kinds of extender pigments. Similarly, the coating composition may contain one kind of rust-preventive pigment or two or more kinds of extender pigments.

[0050] When the coating composition of the present invention contains an extender pigment and / or an anti-rust pigment, the total content of the extender pigment and the anti-rust pigment (pigment content) is, for example, in the range of 20 to 80 parts by mass, and preferably in the range of 30 to 70 parts by mass, per 100 parts by mass of the silicone-modified epoxy resin of the present invention.

[0051] (Other ingredients) The coating composition of the present invention may be in the form of a one-component paint that does not use a curing agent, or in the form of a multi-component paint that uses a curing agent.

[0052] Examples of the curing agent include polyisocyanate compounds, melamine compounds, epoxy compounds, oxazoline compounds, and carbodiimide compounds.

[0053] The coating composition of the present invention may further contain various additives, as necessary, such as a metal drier (which plays a role in promoting the oxidative polymerization of carbon-carbon double bonds in the resin), wax, a surfactant, a stabilizer, a flow modifier, a dye, a leveling agent, a rheology control agent, an ultraviolet absorber, an antioxidant, a plasticizer, an antistatic agent, an antifoaming agent, a viscosity modifier, a light resistance stabilizer, a weather resistance stabilizer, a heat resistance stabilizer, a pigment dispersant, a thermosetting resin, a thermoplastic resin, etc. Known additives can be used.

[0054] The coating composition of the present invention may be applied directly to the article to be coated, or a primer coating material suitable for the article to be coated may be applied first, and then the coating composition of the present invention may be applied.

[0055] Examples of materials for the articles to be coated include various metals such as iron, copper, zinc, aluminum, magnesium, etc. and their alloys; plastic substrates such as polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), PC-ABS polymer alloy, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyamide (PA), polypropylene (PP), fiber-reinforced plastics (FRP) containing fillers such as glass fiber and carbon fiber; and glass.

[0056] As a method for applying the coating composition of the present invention, a known method can be adopted and varies depending on the article to be coated. Examples of the method include methods using a gravure coater, a roll coater, a comma coater, a knife coater, an air knife coater, a curtain coater, a kiss coater, a shower coater, a wheeler coater, a spin coater, dipping, screen printing, spraying, an applicator, a bar coater, a brush, a roller, and the like.

[0057] As a method for curing the coating composition of the present invention after application, a known method can be used. The conditions are adjusted as appropriate depending on the presence or absence of a curing agent, the desired film thickness, and the like, but for example, a method of heating and curing for a certain period of time within a temperature range of about 120 to 350° C. can be used.

[0058] Examples of articles having a cured coating film of the coating composition of the present invention include housings and internal parts of home appliances such as televisions, refrigerators, washing machines, and air conditioners; housings and internal parts of electronic devices such as smartphones, mobile phones, tablet terminals, personal computers, digital cameras, and game consoles; housings of office equipment such as printers and facsimiles; leisure and sports goods; interior and exterior materials for various vehicles such as automobiles, ships, and railway cars; industrial machinery; interior and exterior materials for buildings such as exterior walls, roofs, glass, and decorative panels; and civil engineering components such as soundproofing walls and drainage ditches. EXAMPLES

[0059] The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

[0060] In the examples of the present application, the acid value, hydroxyl value and epoxy equivalent were evaluated by the following methods. [Acid value measurement method] The measurement was performed according to the method of JIS K0070-1992. [Method for measuring hydroxyl value] The measurement was performed according to the method of JIS K0070-1992. [Method for measuring epoxy equivalent] Measurement was performed according to the method of JIS K7236-2009.

[0061] In the examples of the present application, the number average molecular weight and weight average molecular weight of the epoxy resin are values ​​calculated in terms of polystyrene based on GPC measurement, and the measurement conditions are as follows. [GPC measurement conditions] Measurement equipment: Tosoh Corporation's high-speed GPC equipment "HLC-8320GPC" Column: "TSK GURADCOLUMN SuperHZ-L" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation Detector: RI (differential refractometer) Data processing: Tosoh Corporation "EcoSEC Data Analysis Version 1.07" Column temperature: 40℃ Developing solvent: Tetrahydrofuran Flow rate: 0.35mL / min Measurement sample: 7.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran, and the resulting solution was filtered through a microfilter to prepare a measurement sample. Sample injection volume: 20 μl Standard sample: In accordance with the measurement manual for the above-mentioned "HLC-8320GPC," the following monodisperse polystyrene with known molecular weight was used.

[0062] (monodisperse polystyrene) "A-300" manufactured by Tosoh Corporation "A-500" manufactured by Tosoh Corporation "A-1000" manufactured by Tosoh Corporation "A-2500" manufactured by Tosoh Corporation "A-5000" manufactured by Tosoh Corporation "F-1" manufactured by Tosoh Corporation "F-2" manufactured by Tosoh Corporation "F-4" manufactured by Tosoh Corporation "F-10" manufactured by Tosoh Corporation "F-20" manufactured by Tosoh Corporation "F-40" manufactured by Tosoh Corporation "F-80" manufactured by Tosoh Corporation "F-128" manufactured by Tosoh Corporation "F-288" manufactured by Tosoh Corporation

[0063] (Synthesis Example 1: Preparation of Silicone-Modified Epoxy Resin A-1 Having Alkyl Groups) In a four-neck flask equipped with a stirrer, a thermometer, a temperature controller, and a nitrogen inlet tube, 17.0 parts by mass of bisphenol A type epoxy resin "EPICLON 3050" (DIC Corporation, epoxy equivalent 740-860g / Eq), 11.0 parts by mass of bisphenol A type epoxy resin "EPICLON 7050" (DIC Corporation, epoxy equivalent 1750-2100g / Eq), 1.0 parts by mass of lauric acid (Kao Corporation), 23.0 parts by mass of silanol-modified silicone compound "DOWSIL RSN 6018" (Dow Corning Corporation), and 16.0 parts by mass of ortho-xylene as a solvent were charged. These were melted and heated to 130-140°C while stirring, and reacted for 3-4 hours while maintaining the same temperature and dehydrating. After the reaction was completed, the pressure was reduced to remove ortho-xylene, and the residue was diluted with methoxypropyl acetate to obtain a silicone-modified epoxy resin A-1 (non-volatile content 51% by mass) having alkyl groups at the terminals.

[0064] The physical properties of the obtained silicone modified epoxy resin A-1 were as follows: Acid value: 4.9mgKOH / g Epoxy equivalent: 2,000g / Eq Number average molecular weight: 5,000 Weight average molecular weight: 35,000 Decomposition temperature: 420℃

[0065] (Comparative Synthesis Example 1: Preparation of Silicone Modified Epoxy Resin B-1) In a four-neck flask equipped with a stirrer, a thermometer, a temperature controller, and a nitrogen inlet tube, 15.0 parts by mass of bisphenol A type epoxy resin "EPICLON 1055" (DIC Corporation, epoxy equivalent 450-500g / Eq), 25.0 parts by mass of silanol-modified silicone compound "DOWSIL RSN 6018" (Dow Corning Corporation), and 25.0 parts by mass of a cyclohexanone / butyl acetate mixed solvent (cyclohexanone:butyl acetate = 50:50 (mass)) as a solvent were charged. These were melted and heated to 75°C while stirring, 0.05g parts by mass of zinc naphthenate was added as a catalyst, the temperature was raised to 125°C, and the reaction was carried out for 5 hours while maintaining the same temperature and dehydrating to obtain a silicone-modified epoxy resin B-1 (non-volatile content 50% by mass).

[0066] The physical properties of the obtained silicone modified epoxy resin B-1 were as follows: Epoxy equivalent: 475g / Eq Number average molecular weight: 1,200 Weight average molecular weight: 15,000 Decomposition temperature: 360℃

[0067] (Comparative Synthesis Example 2: Preparation of Silicone Modified Epoxy Resin B-2) In a four-neck flask equipped with a stirrer, a thermometer, a temperature controller, and a nitrogen inlet tube, 17.0 parts by mass of bisphenol A type epoxy resin (DIC Corporation's "EPICLON 3050"), 11.0 parts by mass of bisphenol A type epoxy resin (DIC Corporation's "EPICLON 7050"), 24.0 parts by mass of a silanol-modified silicone compound (Dow Corning Corporation's "DOWSIL RSN 6018"), and 16.0 parts by mass of ortho-xylene as a solvent were charged. These were melted and heated to 130-140°C while stirring, and reacted for 3-4 hours while maintaining the same temperature and dehydrating. After the reaction was completed, the pressure was reduced to distill off ortho-xylene, and the mixture was diluted with methoxypropyl acetate to obtain silicone-modified epoxy resin B-2 (non-volatile content 50% by mass).

[0068] The physical properties of the obtained silicone modified epoxy resin B-2 were as follows: Epoxy equivalent: 1,996g / Eq Number average molecular weight: 2,500 Weight average molecular weight: 10,000 Decomposition temperature: 300℃

[0069] (Example 1 and Comparative Examples 1-2: Preparation of Coating Composition, Formation of Coating Film, and Evaluation) The silicone-modified epoxy resins thus produced were used to prepare coating compositions according to the formulations shown in Tables 1 and 2, and the coating compositions thus prepared were applied to the substrates shown in Tables 1 and 2 to form coating films. The coating films thus obtained were evaluated as follows. The results are shown in Tables 1 and 2.

[0070] Specifically, the coating film was formed by applying the coating composition to a substrate with a bar coater so as to give a film thickness of 20 μm, and then baking and heating the coating film for 10 minutes at 270° C. The coating film was evaluated after being left to stand at room temperature of 25° C. for one day.

[0071] (Combination Pattern I) 28.26 parts by mass of the silicone-modified epoxy resin shown in Tables 1 and 2, 28.26 parts by mass of titanium oxide ("Ti-Pure R-960" manufactured by Chemours) and 14.79 parts by mass of propylene glycol monomethyl ether acetate as a solvent were mixed and kneaded for 90 minutes with a paint shaker to obtain a kneaded base. 28.26 parts by mass of the silicone-modified epoxy resin shown in Tables 1 and 2, 0.43 parts by mass of a silicone-based leveling agent ("Modaflow 2100" manufactured by ALLNEX) and 14.79 parts by mass of propylene glycol monomethyl ether acetate were further added to the obtained kneaded base and mixed to prepare a coating composition with a non-volatile content of 57% by mass and a pigment mass concentration of 50% by mass.

[0072] (Combination Pattern II) 28.22 parts by mass of silicone-modified epoxy resin shown in Tables 1 and 2, 28.22 parts by mass of titanium oxide ("Ti-Pure R-960" manufactured by Chemours), 28.22 parts by mass of carbon black ("Carbon Black 1000" manufactured by Mitsubishi Chemical Corporation) and 14.77 parts by mass of propylene glycol monomethyl ether acetate as a solvent were mixed and kneaded for 90 minutes with a paint shaker to obtain a kneaded base. 28.22 parts by mass of silicone-modified epoxy resin shown in Tables 1 and 2, 0.43 parts by mass of silicone-based leveling agent ("Modaflow 2100" manufactured by ALLNEX) and 14.79 parts by mass of propylene glycol monomethyl ether acetate were further added and mixed to the obtained kneaded base to prepare a coating composition with a non-volatile content of 57% by mass and a pigment mass concentration of 50% by mass.

[0073] (Storage stability) The prepared coating composition was stored at room temperature of 25° C. for 3 months, and a coating film was formed using the coating composition after storage by the above-mentioned method. The obtained coating film was visually evaluated according to the following criteria. A: No blisters (bubbles) or discoloration (yellowing, etc.) are observed on the coating surface. B: Blisters (bubbles) and / or discoloration (yellowing, etc.) are observed on the coating surface. C: The coating does not adhere to the substrate.

[0074] (gloss value) The gloss of the coating film formed on the substrate was measured at any five points at an incidence angle of 60° and a reflection angle of 60° using a gloss meter Micro-Tri-Gloss (manufactured by BYK), and the measured values ​​were taken as the gloss value. The gloss value is an index of pigment dispersion, with a higher value indicating that the pigment is better dispersed.

[0075] (Adhesion to substrate) The coating film formed on the substrate was evaluated for its adhesion to the substrate based on JIS K-5400:1990. Specifically, 1 mm-wide cuts were made on the coating film with a cutter to make 100 squares, and cellophane tape was applied so as to cover all the squares, which were then quickly peeled off. The number of squares remaining in contact after the test was expressed as a percentage. In terms of substrate adhesion, 100% means that no coating peeled off, and 0% means that the entire coating peeled off. Adhesion of 95% or more can be considered to be sufficient for practical use.

[0076] (Konig hardness) The Koenig hardness of the coating film formed on the substrate was measured in accordance with ISO1522.

[0077] (Pencil hardness) The pencil hardness of the coating film formed on the substrate was measured in accordance with EN13523-4.

[0078] (Heat resistance) The coated substrate was placed in a ceramic oven and heated at 600°C for 10 minutes. After heating, the coated substrate was immersed in water at room temperature. This process was repeated five times. After five cycles, the coating surface of the coated substrate was visually inspected and evaluated according to the following criteria: A: No scratches, discoloration or blisters on the coating surface B: At least one of the following is present on the coating surface: scratches, discoloration, and blisters. C: The coating is completely damaged.

[0079] (Adhesion to substrate after heating) Those that were rated "A (no scratches, discoloration or blisters on the coating surface)" in the heat resistance evaluation were subjected to the above-mentioned substrate adhesion evaluation again.

[0080] [Table 1]

[0081] [Table 2]

[0082] From Tables 1 and 2, it can be seen that the coating film made using the coating composition containing the silicone-modified epoxy resin A-1 having an alkyl group has high heat resistance. On the other hand, it can be seen that the coating film made using the coating composition containing the silicone-modified epoxy resin B-1 (having no alkyl group) does not have sufficient heat resistance. In the coating film made using the coating composition containing the silicone-modified epoxy resin B-2 (having no alkyl group), the epoxy equivalent of the silicone-modified epoxy resin B-2 is high, so the compatibility with the pigment is insufficient and the coating film loses gloss. In addition, since the pigment dispersion is insufficient, it is expected that voids are generated in the coating film, and heat resistance is not obtained.

Claims

1. A silicone-modified epoxy resin having as reaction components an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid, A silicone-modified epoxy resin having an epoxy equivalent in the range of 1,000 to 3,000 g / equivalent and an alkyl group having 10 or more carbon atoms.

2. 2. The silicone-modified epoxy resin according to claim 1, which has a bisphenol structure.

3. 3. The silicone-modified epoxy resin according to claim 1, having an acid value in the range of 1 to 10 mgKOH / g.

4. 3. The silicone-modified epoxy resin according to claim 1, wherein the epoxy resin having a hydroxyl group is a bisphenol-type epoxy resin having a hydroxyl group.

5. The silicone compound having a silanol group is R ３ SiO １／２ Units (M units), SiO ４／２ Unit (Q unit), R ２ SiO ２／２ Units (D units) and RSiO ３／２ 3. The silicone-modified epoxy resin according to claim 1 or 2, which is a silicone compound having one or more siloxy units selected from units (T units) (R is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyl group), has two or more silanol groups, and the proportion of phenyl groups in R in the siloxy units is 50 mol % or more.

6. 3. The silicone-modified epoxy resin according to claim 1, wherein the fatty acid is a saturated fatty acid having 11 to 22 carbon atoms.

7. 3. The silicone-modified epoxy resin according to claim 1, wherein, in the reaction components, the epoxy resin is in a range of 30 to 60 parts by mass, the silicone compound having a silanol group is in a range of 20 to 50 parts by mass, and the fatty acid is in a range of 1 to 5 parts by mass.

8. A coating composition comprising the silicone-modified epoxy resin according to claim 1 or 2 and a pigment.

9. A cured product of the coating composition according to claim 8.

10. An article coated with the cured coating composition according to claim 8.

11. A metal member coated with the cured product of the coating composition according to claim 8.

Images