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

Abstract

Provided are: a silicone-modified epoxy resin which is capable of exhibiting high heat resistance when cured; and a coating composition which contains the silicone-modified epoxy resin. Specifically, the silicone-modified epoxy resin has an epoxy equivalent in the range of 1,000-3,000 g / equivalent and has an alkyl group having 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 Art

[0002] As a method for imparting heat resistance and corrosion resistance (weather resistance) to industrial metal members such as steel sheets for automobiles, steel pipes for gas pipelines, and metal materials for construction, and household metal members such as frying pans and barbecue grills, a method of protecting and coating the surface of the metal member with a resin is widely used.

[0003] In particular, for motorcycle mufflers and steel pipes for gas pipelines that require high heat resistance and corrosion resistance, protection coating is usually carried out using an epoxy resin.

[0004] As the above-mentioned epoxy resin, a silicone-modified epoxy resin modified with silicone (for example, Patent Document 1) is known. This silicone-modified epoxy resin improves heat resistance by introducing a siloxane bond with high bond strength into the epoxy resin.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-521020 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] The epoxy resin of 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.

[0010] In order to improve the heat resistance of the epoxy resin itself, high crosslinking can be set. However, if the epoxy equivalent is increased to achieve high crosslinking, the viscosity also increases, and there is a problem that the compatibility with pigments that impart various functions to the coating layer, such as extender pigments and rust-inhibiting pigments, is significantly reduced. When the compatibility between the epoxy resin and the pigment cannot be ensured, voids are generated in the resulting coating layer, and the heat resistance of the coating layer is impaired. Therefore, there is a natural upper limit to the epoxy equivalent of the epoxy resin for coating.

[0011] The problem to be solved by the present invention is to provide a silicone-modified epoxy resin whose resulting cured product can exhibit high heat resistance and a coating composition containing the resin.

[0012] Means for Solving the Problems

[0013] The present inventors conducted in-depth research to solve the above problems and found that by introducing an alkyl group having 10 or more carbon atoms into a silicone-modified epoxy resin, high viscosity increase can be suppressed and compatibility with pigments can also be ensured, thereby completing the present invention.

[0014] That is, the present invention relates to the following silicone-modified epoxy resins and the like.

[0015] 1. A silicone-modified epoxy resin having an epoxy equivalent in the range of 1,000 to 3,000 g / equivalent and having an alkyl group having 10 or more carbon atoms.

[0016] 2. The silicone-modified epoxy resin according to 1, which has a bisphenol structure.

[0017] 3. The silicone-modified epoxy resin according to 1 or 2, which has an acid value in the range of 1 to 10 mgKOH / g.

[0018] 4. The silicone-modified epoxy resin according to any one of 1 to 3, which uses an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid as reaction components.

[0019] 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.

[0020] 6. The silicone-modified epoxy resin according to 4 or 5, wherein the silicone compound having a silanol group has one or more silyloxy units selected from R3SiO 1 / 2 unit (M unit), SiO 4 / 2 unit (Q unit), R2SiO 2 / 2 unit (D unit), and RSiO 3 / 2 unit (T unit) (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 has two or more silanol groups, and the proportion of phenyl groups in R in the above silyloxy units is 50 mol% or more.

[0021] 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.

[0022] 8. The silicone-modified epoxy resin according to any one of 4 to 7, wherein in the above 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.

[0023] 9. A coating composition containing the silicone-modified epoxy resin according to any one of 1 to 8 and a pigment.

[0024] 10. A cured product which is a cured product of the coating composition described in 9.

[0025] 11. An article which is an article coated with the cured product of the coating composition described in 9.

[0026] 12. A metal member which is a metal member coated with the cured product of the coating composition described in 9.

[0027] Advantages of the Invention

[0028] According to the present invention, a silicone-modified epoxy resin capable of exhibiting high heat resistance can be provided.

[0029] According to the present invention, a coating composition capable of obtaining a coating layer exhibiting high heat resistance can be provided. Detailed Embodiments

[0030] Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the following embodiments and can be appropriately modified and implemented within the scope not impairing the effects of the present invention.

[0031] It should be noted that the compounds in this specification can be derived from fossil resources or biological resources.

[0032] [Silicone-Modified Epoxy Resin]

[0033] The epoxy equivalent of the silicone-modified epoxy resin of the present invention is in the range of 1,000 to 3,000 g / equivalent and has an alkyl group having 10 or more carbon atoms.

[0034] For the silicone-modified epoxy resin of the present invention, although it has a high epoxy equivalent, by introducing an alkyl group having 10 or more carbon atoms, an increase in viscosity can be suppressed. In addition, by introducing an alkyl group having 10 or more carbon atoms, compatibility with a pigment described later can also be ensured.

[0035] It should be noted that 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.

[0036] In the present invention, it is preferable that at least one of the terminal epoxy groups of the silicone-modified epoxy resin is 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.

[0037] The alkyl group having 10 or more carbon atoms in the silicone-modified epoxy resin of the present invention is preferably an alkyl group having 12 to 22 carbon atoms, more preferably an alkyl group having 12 to 18 carbon atoms.

[0038] The alkyl group having 10 or more carbon atoms in the silicone-modified epoxy resin of the present invention can be either a branched alkyl group or a straight-chain alkyl group, and is preferably a straight-chain alkyl group.

[0039] The epoxy equivalent of the silicone-modified epoxy resin of the present invention is 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.

[0040] The epoxy equivalent of the silicone-modified epoxy resin of the present invention is evaluated by the method described in the examples.

[0041] 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 further preferably in the range of 1 to 6 mgKOH / g.

[0042] The acid value of the silicone-modified epoxy resin of the present invention is evaluated by the method described in the examples.

[0043] The number-average molecular weight of the silicone-modified epoxy resin of the present invention is not particularly limited, and 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.

[0044] The weight-average molecular weight of the silicone-modified epoxy resin of the present invention is not particularly limited, and is, for example, in the range of 10,000 to 50,000, preferably in the range of 20,000 to 40,000.

[0045] The number-average molecular weight and the weight-average molecular weight of the silicone-modified epoxy resin of the present invention are evaluated by the method described in the examples.

[0046] The silicone-modified epoxy resin of the present invention preferably uses an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid as reaction components.

[0047] Here, the "reaction components" refer to the components that constitute the structure of the silicone-modified epoxy resin, and do not include solvents and catalysts that do not constitute the structure of the silicone-modified epoxy resin.

[0048] Hereinafter, each component will be described.

[0049] (Epoxy resin having a hydroxyl group)

[0050] Epoxy resins are resins having at least one epoxy group in the molecule. Examples thereof include bisphenol A type, bisphenol F type, bisphenol E type, bisphenol B type, bisphenol S type, bisphenol AD type, bisphenol AP type, bisphenol BP type and other bisphenol type epoxy resins; phenol novolac type, cresol novolac type and other novolac type epoxy resins; resorcinol type epoxy resins; aromatic epoxy resins such as triphenylmethane triglycidyl ether; naphthalene type epoxy resins; fluorene type epoxy resins; biphenyl type epoxy resins and the like.

[0051] The epoxy resin having a hydroxyl group in the present invention is, for example, the above-mentioned epoxy resin further having a hydroxyl group.

[0052] 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).

[0053] [Chemical formula 1]

[0054]

[0055] (In the above general formula (A-1),

[0056] X is a bisphenol structure represented by the following general formula (A-2),

[0057] n is the number of repetitions.)

[0058] [Chemical formula 2]

[0059]

[0060] (In the above general formula (A-2),

[0061] R 1 and R 2 are each independently an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms,

[0062] n1 and n2 are each independently an integer in the range of 0 to 4,

[0063] 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 thioether bond (-S-) or a sulfonyl bond (-SO2-).)

[0064] For the general formula (A-2), when there are a plurality of R 1 , the plurality of R 1 may be the same as or different from each other. Similarly, when there are a plurality of R 2 , the plurality of R 2 may be the same as or different from each other.

[0065] In the case of an epoxy resin having a hydroxyl group, such as the compound represented by the above general formula (A-1), the epoxy group of the compound represented by the general formula (A-1) reacts with a fatty acid to introduce an alkyl group at the terminal.

[0066] The epoxy equivalent of the epoxy resin having a hydroxyl group 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 still more preferably in the range of 600 to 3,000 g / equivalent.

[0067] It should be noted that the epoxy equivalent is the weight of the epoxy resin required to obtain 1 mol amount of epoxy groups and is measured by the method described in the examples.

[0068] In the present invention, it is only necessary to use the epoxy resin having a hydroxyl group such that the average epoxy equivalent thereof falls within the range of 1,000 to 3,000 g / equivalent. For example, in the case of using two epoxy resins having a hydroxyl group, it is only necessary to use them such that the average epoxy equivalent calculated according to (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.

[0069] As the epoxy resin having a hydroxyl group, commercially available products can be used. Examples of such commercially available products include EPICLON 1055, EPICLON 3040, EPICLON 3050, EPICLON 4050, EPICLON 7050 (all manufactured by DIC Corporation), LAPOXP-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), E-51 (epoxy equivalent 184 to 194 g / Eq) (all manufactured by Sinopec Corporation), etc.

[0070] (Silicone compound having a silanol group)

[0071] Regarding the silicone compound having a silanol group, the above silanol group reacts with the hydroxyl group of the epoxy resin to form a crosslinked structure that crosslinks the epoxy resins with each other.

[0072] The silicone compound having a silanol group is preferably a silicone compound having two or more silanol groups, and more preferably a silicone compound having a unit selected from R3SiO 1 / 2 unit (M unit), SiO 4 / 2 unit (Q unit), R2SiO 2 / 2 unit (D unit) and RSiO3 / 2 A compound having one or more siloxane units in a unit (T unit) (where 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.

[0073] In the case where the silicone compound having a silanol group has one or more siloxane units selected from R3SiO 1 / 2 units (M units), SiO 4 / 2 units (Q units), R2SiO 2 / 2 units (D units), and RSiO 3 / 2 units (T units) (where 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, it is preferred that the proportion of the phenyl group in R in the above siloxane units is 50 mol% or more.

[0074] By setting the proportion of the phenyl group in R in the above siloxane units to 50 mol% or more, the heat resistance can be improved.

[0075] The proportion of the phenyl group in the siloxane unit can be confirmed by Fourier transform infrared spectroscopy (FTIR), and the upper limit of the proportion of the phenyl group in the siloxane unit is, for example, 80 mol%.

[0076] Commercially available products can be used as the silicone compound having a silanol group. Examples of such commercially available products include DOWSIL RSN-6018, DOWSIL RSN-0220, DOWSIL 3040 (all manufactured by Dow Chemical Company), etc.

[0077] It should be noted that regarding the proportion of the phenyl group in R in the above commercially available products' siloxane units, it is 73 mol% in DOWSIL RSN-6018, 67 mol% in DOWSIL RSN-0220, and 50 mol% in DOWSIL 3040.

[0078] (Fatty acid)

[0079] 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 further preferably a straight-chain saturated fatty acid having 11 to 18 carbon atoms.

[0080] The fatty acid can be used alone or in combination of two or more.

[0081] As specific examples of the fatty acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, heneicosanoic acid, behenic acid, etc. can be cited.

[0082] As the reaction component, an oil containing a fatty acid can also be used.

[0083] As the above-mentioned fat, hydrogenated coconut oil fatty acid, hydrogenated palm kernel oil fatty acid, hydrogenated palm oil fatty acid, hydrogenated olive oil fatty acid, hydrogenated castor oil fatty acid, hydrogenated rapeseed oil fatty acid, etc. can be cited. They are obtained by hydrolyzing and hydrogenating the oil agents obtained from coconut, palm kernel, palm, olive, castor, and rapeseed respectively, and are all mixtures of two or more long-chain aliphatic monocarboxylic acids.

[0084] The silicone-modified epoxy resin of the present invention only needs to use an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid as reaction components, and components other than these can be further used within the range not impairing the effects of the present invention.

[0085] 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.

[0086] With respect to 100 parts by mass of the epoxy resin having a hydroxyl group, the compounding 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.

[0087] With respect to 100 parts by mass of the epoxy resin having a hydroxyl group, the compounding 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 further preferably in the range of 3 to 4 parts by mass.

[0088] Regarding the compounding ratio of each component in the reaction components, it is preferable that the epoxy resin having a hydroxyl group is in the range of 30 to 60 parts by mass, the silicone-modified silicone compound 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.

[0089] The reaction of the epoxy resin having a hydroxyl group, the silicone compound having a silanol group, and the fatty acid can be carried out by a known method. For example, the silicone-modified epoxy resin of the present invention can be prepared by heating a reaction system containing the epoxy resin having a hydroxyl group, the silicone compound having a silanol group, and the fatty acid. In addition, for example, by reacting the epoxy resin having a hydroxyl group with the silicone compound having a silanol group to form a silicone-modified epoxy resin, and further reacting with a fatty acid, the silicone-modified epoxy resin of the present invention can also be prepared.

[0090] [Coating Composition]

[0091] 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 in a solvent.

[0092] Examples of the solvent for the coating composition of the present invention include alcohol solvents such as methanol, ethanol, propanol, n-butanol, isobutanol, 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; dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, and the like.

[0093] The solvent can be used alone as one kind, or two or more kinds can be used in combination.

[0094] For the coating composition of the present invention, the solvent can be used, for example, in such a manner that the solid component concentration becomes 10 to 80% by mass, and preferably in such a manner that the solid component concentration becomes 50 to 70% by mass.

[0095] The coating composition of the present invention can ensure sufficient pigment compatibility.

[0096] Among the above pigments, for example, there are pigments called "extender pigments" and pigments called "rust-inhibiting pigments". Extender pigments are pigments incorporated for the purpose of modifying (extending, coloring, drying, etc.) the resin composition, and rust-inhibiting pigments are pigments incorporated to improve the corrosion resistance of the resin composition.

[0097] 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, silicon dioxide, zeolite, talc, and the like.

[0098] Specific examples of rust-inhibiting pigments include phosphates, hydrogen phosphates, phosphosilicates, borosilicates, borates, metaborates, molybdates, chromates, polyphosphates, etc. of one or more metals selected from calcium, strontium, barium, zinc, aluminum, and magnesium.

[0099] The coating composition of the present invention only needs to contain at least one of extender pigments and rust-inhibiting pigments.

[0100] The extender pigment contained in the coating composition may be one kind alone or two or more kinds. Similarly, the anti-rust pigment contained in the coating composition may be one kind alone or two or more kinds.

[0101] 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 (content of the pigment) is, for example, in the range of 20 to 80 parts by mass, preferably in the range of 30 to 70 parts by mass, based on 100 parts by mass of the silicone-modified epoxy resin of the present invention.

[0102] (Other components)

[0103] 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.

[0104] Examples of the above-mentioned curing agent include polyisocyanate compounds, melamine compounds, epoxy compounds, oxazoline compounds, carbodiimide compounds, etc.

[0105] The coating composition of the present invention may further contain various additives such as metal driers (which play a role in promoting the oxidative polymerization of carbon-carbon double bonds in the resin), waxes, surfactants, stabilizers, flow regulators, dyes, leveling agents, rheology control agents, ultraviolet absorbers, antioxidants, plasticizers, antistatic agents, defoamers, viscosity regulators, light stabilizers, weather stabilizers, heat stabilizers, pigment dispersants, thermosetting resins, thermoplastic resins, etc., as needed. Known substances can be used for them.

[0106] The coating composition of the present invention can be directly applied to an article to be coated, or can be applied after applying a primer suitable for the article to be coated.

[0107] Examples of the material of the article to be coated include various metals such as iron, copper, zinc, aluminum, magnesium 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) added with fillers such as glass fiber and carbon fiber; glass, etc.

[0108] As the coating method of the coating composition of the present invention, known methods can be adopted, which vary depending on the article to be coated. For example, there are methods such as gravure coater, roll coater, comma coater, knife coater, air knife coater, curtain coater, kiss coater, spray coater, spin coater (Japanese: ホイーラーコーター), spin coater, dipping, screen printing, spray gun, applicator, rod coater, brush, roll, etc.

[0109] For the post-application curing method of the coating composition of the present invention, a well-known method can also be adopted.

[0110] Adjust the conditions appropriately according to the presence or absence of a curing agent, the target film thickness, etc. 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 adopted.

[0111] Examples of articles having the cured coating film of the coating composition of the present invention include the casings and internal components of home appliances such as televisions, refrigerators, washing machines, and air conditioners; the casings and internal components of electronic devices such as smartphones, mobile phones, tablet terminals, personal computers, digital cameras, and game consoles; the casings of OA equipment such as printers and fax machines; leisure and sports goods; interior and exterior decorative materials for various vehicles such as automobiles, ships, and railway vehicles; industrial machinery; interior and exterior decorative materials for buildings such as exterior walls, roofs, glass, and decorative panels; civil engineering components such as sound insulation walls and drainage ditches.

[0112] Examples

[0113] Hereinafter, the present invention will be specifically described by way of examples and comparative examples.

[0114] It should be noted that the present invention is not limited to the following examples.

[0115] In the examples of the present application, the values of acid value, hydroxyl value, and epoxy equivalent are the values obtained by evaluation through the following methods.

[0116] [Method for measuring acid value]

[0117] Measure by the method according to JIS K0070-1992.

[0118] [Method for measuring hydroxyl value]

[0119] Measure by the method according to JIS K0070-1992.

[0120] [Method for measuring epoxy equivalent]

[0121] Measure by the method according to JIS K7236-2009.

[0122] In the examples of the present application, the number-average molecular weight and weight-average molecular weight of the epoxy resin are the values obtained by GPC measurement and polystyrene conversion, and the measurement conditions are as follows.

[0123] [GPC measurement conditions]

[0124] Measurement device: High-speed GPC device “HLC-8320GPC” manufactured by Tosoh Corporation

[0125] 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

[0126] Detector: RI (Differential Refractometer)

[0127] Data processing: "EcoSEC Data Analysis Version 1.07" manufactured by Tosoh Corporation

[0128] Column temperature: 40 °C

[0129] Eluent: Tetrahydrofuran

[0130] Flow rate: 0.35 mL / min

[0131] Test sample: Dissolve 7.5 mg of the sample in 10 ml of tetrahydrofuran, filter the resulting solution through a microfilter, and use the obtained product as the test sample.

[0132] Sample injection volume: 20 μl

[0133] Standard sample: According to the measurement manual of the above-mentioned "HLC-8320GPC", use the following monodisperse polystyrene with known molecular weight.

[0134] (Monodisperse polystyrene)

[0135] "A-300" manufactured by Tosoh Corporation

[0136] "A-500" manufactured by Tosoh Corporation

[0137] "A-1000" manufactured by Tosoh Corporation

[0138] "A-2500" manufactured by Tosoh Corporation

[0139] "A-5000" manufactured by Tosoh Corporation

[0140] "F-1" manufactured by Tosoh Corporation

[0141] "F-2" manufactured by Tosoh Corporation

[0142] "F-4" manufactured by Tosoh Corporation

[0143] "F-10" manufactured by Tosoh Corporation

[0144] "F-20" manufactured by Tosoh Corporation

[0145] “F-40” manufactured by Tosoh Corporation

[0146] “F-80” manufactured by Tosoh Corporation

[0147] “F-128” manufactured by Tosoh Corporation

[0148] “F-288” manufactured by Tosoh Corporation

[0149] (Synthesis Example 1: Preparation of silicone-modified epoxy resin A-1 having an alkyl group)

[0150] In a four-necked flask equipped with a stirrer, a thermometer, a temperature control device, and a nitrogen inlet tube, 17.0 parts by mass of bisphenol A type epoxy resin “EPICLON 3050” (manufactured by DIC Corporation, epoxy equivalent 740 - 860 g / Eq), 11.0 parts by mass of bisphenol A type epoxy resin “EPICLON 7050” (manufactured by DIC Corporation, epoxy equivalent 1750 - 2100 g / Eq), 1.0 part by mass of lauric acid (manufactured by Kao Corporation), 23.0 parts by mass of silanol-modified silicone compound “DOWSIL RSN 6018” (manufactured by Dow Corning Corporation), and 16.0 parts by mass of o-xylene as a solvent were charged. While melting and stirring them, the temperature was raised to 130 - 140 °C, and dehydration was carried out while maintaining this temperature, and the reaction was carried out for 3 - 4 hours. After completion of the reaction, o-xylene was removed by distillation under reduced pressure and diluted with methoxypropyl acetate to obtain silicone-modified epoxy resin A-1 having an alkyl group at the terminal (non-volatile content 51 mass%).

[0151] The physical properties of the obtained silicone-modified epoxy resin A-1 are as follows:

[0152] Acid value: 4.9 mgKOH / g

[0153] Epoxy equivalent: 2,000 g / Eq

[0154] Number average molecular weight: 5,000

[0155] Weight average molecular weight: 35,000

[0156] Decomposition temperature: 420 °C

[0157] (Synthesis Comparative Example 1: Preparation of silicone-modified epoxy resin B-1)

[0158] In a four-necked flask equipped with a stirrer, a thermometer, a temperature control device, and a nitrogen inlet tube, 15.0 parts by mass of bisphenol A type epoxy resin “EPICLON 1055” (manufactured by DIC Corporation, epoxy equivalent 450 - 500 g / Eq), 25.0 parts by mass of a silanol-modified silicone compound “DOWSIL RSN 6018” (manufactured by Dow Corning), and 25.0 parts by mass of a mixed solvent of cyclohexanone / butyl acetate (cyclohexanone:butyl acetate = 50:50 (mass)) as a solvent were charged. While melting and stirring them, the temperature was raised to 75°C, 0.05 g by mass of zinc naphthenate as a catalyst was added, the temperature was raised to 125°C, and dehydration was carried out while maintaining this temperature and the reaction was carried out for 5 hours to obtain silicone-modified epoxy resin B-1 (non-volatile content 50 mass%).

[0159] The physical properties of the obtained silicone-modified epoxy resin B-1 are as follows:

[0160] Epoxy equivalent: 475 g / Eq

[0161] Number average molecular weight: 1,200

[0162] Weight average molecular weight: 15,000

[0163] Decomposition temperature: 360°C

[0164] (Synthesis Comparative Example 2: Preparation of silicone-modified epoxy resin B-2)

[0165] In a four-necked flask equipped with a stirrer, a thermometer, a temperature control device, 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's “DOWSIL RSN6018”), and 16.0 parts by mass of o-xylene as a solvent were charged. While melting and stirring them, the temperature was raised to 130 - 140°C, dehydration was carried out while maintaining this temperature, and the reaction was carried out for 3 - 4 hours. After the reaction was completed, o-xylene was removed by distillation under reduced pressure and diluted with methoxypropyl acetate to obtain silicone-modified epoxy resin B-2 (non-volatile content 50 mass%).

[0166] The physical properties of the obtained silicone-modified epoxy resin B-2 are as follows:

[0167] Epoxy equivalent: 1,996 g / Eq

[0168] Number average molecular weight: 2,500

[0169] Weight-average molecular weight: 10,000

[0170] Decomposition temperature: 300 °C

[0171] (Examples 1 and Comparative Examples 1-2: Preparation, film formation, and evaluation of coating compositions)

[0172] Using the produced silicone-modified epoxy resin, coatings were prepared in the formulation shown in Tables 1 and 2, and the prepared coating compositions were applied to the substrates shown in Tables 1 and 2 to form a coating film. The following evaluations were performed on the obtained coating film. The results are shown in Tables 1 and 2.

[0173] It should be noted that regarding the formation of the above coating film, specifically, the coating composition was applied to the substrate with a bar coater to a film thickness of 20 μm, and heat treatment was performed at 270 °C for 10 minutes to form a coating film. The coating film used in the evaluation of the coating film was the one left standing at room temperature of 25 °C for 1 day.

[0174] (Formulation I)

[0175] 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 with a paint stirrer for 90 minutes to obtain a kneaded base material. Further, 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 added to the obtained kneaded base material and mixed to prepare a coating composition having a nonvolatile content of 57% by mass and a pigment mass concentration of 50% by mass.

[0176] (Formulation II)

[0177] 28.22 parts by mass of the 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 Company), 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 with a paint stirrer for 90 minutes to obtain a kneaded base material. Further, 28.22 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 added to the obtained kneaded base material and mixed to prepare a coating composition having a nonvolatile content of 57% by mass and a pigment mass concentration of 50% by mass.

[0178] (Storage stability)

[0179] The prepared coating composition was stored at room temperature of 25 °C for 3 months. Using the stored coating composition, a coating film was formed by the above method, and the obtained coating film was evaluated visually according to the following criteria.

[0180] A: No blistering (bubble swelling) and discoloration (yellowing, etc.) were confirmed on the surface of the coating film.

[0181] B: Blistering (bubble swelling) and / or discoloration (yellowing, etc.) were confirmed on the surface of the coating film.

[0182] C: The coating film did not adhere closely to the substrate.

[0183] (Gloss value)

[0184] For the coating film formed on the substrate, the gloss at an incident angle of 60° and a reflection angle of 60° was measured at any 5 points using a gloss meter Micro-Tri-Gloss (manufactured by BYK), and the measured value was used as the gloss value.

[0185] It should be noted that the gloss value is an index of pigment dispersion, and the higher the value, the better the pigment is dispersed.

[0186] (Substrate adhesion)

[0187] For the coating film formed on the substrate, the substrate adhesion was evaluated based on JIS K-5400:1990. Specifically, a 1-mm-wide incision was made on the coating film with a cutter, the number of checkerboards was set to 100, and a transparent tape was attached so as to cover all the checkerboards and then quickly peeled off. The number of checkerboards that remained adhered after the test was expressed as a percentage.

[0188] Regarding the substrate adhesion, 100% means the non-peeling part of the coating film, and 0% means the complete peeling of the coating film. If more than 95% adhesion is confirmed, it can be regarded as a performance without practical problems.

[0189] (Konig hardness)

[0190] For the coating film formed on the substrate, the Konig hardness was measured in accordance with ISO1522.

[0191] (Pencil hardness)

[0192] For the coating film formed on the substrate, the pencil hardness was measured in accordance with EN13523-4.

[0193] (Heat resistance)

[0194] The coated substrate was placed in a ceramic furnace and heated at 600°C for 10 minutes. The heated coated substrate was immersed in water at room temperature, and this operation was repeated 5 times. The surface of the coating film of the coated substrate after repeating 5 times was visually confirmed and evaluated according to the following criteria:

[0195] A: There is no damage, discoloration, or blistering on the surface of the coating film

[0196] B: There is at least one of damage, discoloration, and blistering on the surface of the coating film

[0197] C: The entire coating film is damaged

[0198] (Substrate adhesion after heating)

[0199] For the case where the evaluation in heat resistance is "A (no damage, discoloration, or blistering on the surface of the coating film)", the above-mentioned substrate adhesion evaluation was performed again.

[0200] [Table 1]

[0201]

[0202] [Table 2]

[0203]

[0204] As can be seen from Table 1 and Table 2, a coating film obtained using a coating composition containing silicone-modified epoxy resin A-1 having an alkyl group can achieve high heat resistance. On the other hand, it can be seen that for a coating film obtained using a coating composition containing silicone-modified epoxy resin B-1 (without an alkyl group), sufficient heat resistance cannot be obtained. For a coating film obtained using a coating composition containing silicone-modified epoxy resin B-2 (without an alkyl group), due to the high epoxy equivalent of silicone-modified epoxy resin B-2, the compatibility with the pigment becomes insufficient, and the gloss of the coating film is lost. In addition, due to insufficient pigment dispersion, it can be expected that voids will be generated in the coating film, and heat resistance cannot be obtained either.

Claims

1. A silicone-modified epoxy resin having an epoxy equivalent in the range of 1,000 g / equivalent to 3,000 g / equivalent and having an alkyl group with 10 or more carbon atoms.

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

3. The silicone-modified epoxy resin according to claim 1 or 2, having an acid value in the range of 1 mgKOH / g to 10 mgKOH / g.

4. The silicone-modified epoxy resin according to claim 1 or 2, which uses an epoxy resin having a hydroxyl group, a silicone compound having a silanol group, and a fatty acid as reaction components.

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

6. The silicone-modified epoxy resin according to claim 4, wherein, The silicone compound having a silanol group has at least one siloxane unit selected from a unit called an M unit, R3SiO 1 / 2 unit, a unit called a Q unit, SiO 4 / 2 unit, a unit called a D unit, R2SiO 2 / 2 unit, and a unit called a T unit, RSiO 3 / 2 unit, and has two or more silanol groups, where 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. The proportion of phenyl groups in R in the silyloxy unit is 50 mol% or more.

7. The silicone-modified epoxy resin according to claim 4, wherein, The fatty acid is a saturated fatty acid having 11 to 22 carbon atoms.

8. The silicone-modified epoxy resin according to claim 4, wherein, Among the reaction components, the epoxy resin is in the range of 30 parts by mass to 60 parts by mass, the silicone compound having a silanol group is in the range of 20 parts by mass to 50 parts by mass, and the fatty acid is in the range of 1 part by mass to 5 parts by mass.

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

10. A cured product which is a cured product of the coating composition according to claim 9.

11. An article which is an article coated with the cured product of the coating composition according to claim 9.

12. A metal member which is a metal member coated with the cured product of the coating composition according to claim 9.

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