Aqueous organopolysiloxane dispersion, method for producing aqueous organopolysiloxane dispersion, coating agent, cured product, and coated article

Abstract

An organic polysiloxane aqueous dispersion comprising (A) an organic polysiloxane represented by the following formula (I): 100 parts by mass, (B) a basic compound: an amount to make the pH 7 to 10, and (C) water: 50 to 1000 parts by mass, the stability of the organic polysiloxane aqueous dispersion is high, and the curability is excellent.(R 1 represents a hydrogen atom, a monovalent saturated hydrocarbon group, an organic group having a radically polymerizable functional group, an aryl group, or an aralkyl group, R 2 represents a monovalent group having a carboxylic anhydride structure, a carboxylic acid structure, or a carboxylic acid salt structure, R 3 represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an i-propyl group, a, b, c, d, and e are numbers satisfying 0 f is a number satisfying 0

Description

Technical Field

[0001] This invention relates to aqueous dispersions of organopolysiloxanes, methods for manufacturing aqueous dispersions of organopolysiloxanes, coating agents, cured products, and coated articles. Background Technology

[0002] Organopolysiloxane resins containing silanol groups are widely used in coatings and coating agents. Generally, when external energy such as heat is applied to organopolysiloxane resins, the terminal silanol groups react with each other to form a strong siloxane network. As a result, the resulting coating has excellent heat resistance and weather resistance, making it suitable for a wide range of applications, from outdoor buildings to automotive parts and electronic components.

[0003] On the other hand, while organopolysiloxane coatings have the advantages mentioned above, they also have the following disadvantages: if organopolysiloxanes are used alone, they are solids or high-viscosity liquids, therefore, they need to be diluted with solvents before use, and the curing speed is slow, requiring high-temperature heating for curing.

[0004] To address these shortcomings, studies have been conducted on weak solvent dilution, aqueous dispersions, and low-temperature curing of organopolysiloxane resins.

[0005] For example, in Patent Document 1, it is reported that resins diluted with conventional toluene, which are environmentally friendly solvents without TX, are used as diluents. The xylene-based solvent is replaced with an acetate-based solvent, thereby improving curability without TX solvation.

[0006] In Patent Document 2, an aqueous dispersion of organosilicon resin was obtained by reacting a lower molecular weight organopolysiloxane with a cationic alkoxysilane, but it has the problems of low curability and poor solvent resistance of the resulting cured film.

[0007] Patent document 3 reports a method of curing at a low temperature of around 100°C by combining two or more organopolysiloxanes with different molecular weights and adding a catalyst. However, since curing at low temperatures requires a catalyst, it has the disadvantage of being difficult to industrialize from the perspective of the shelf life.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2021-172706

[0011] Patent Document 2: Japanese Patent Publication No. 2013-515154

[0012] Patent Document 3: Japanese Patent Application Publication No. 2021-172707 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] The present invention was made in view of the above-mentioned actual situation, and its purpose is to provide an aqueous dispersion of organopolysiloxane with high stability and excellent curability.

[0015] Methods for solving problems

[0016] In order to achieve the above objectives, the inventors conducted repeated and in-depth research and found that an aqueous dispersion of an organopolysiloxane containing an organopolysiloxane having a cyclic carboxylic anhydride structure, or a carboxylic acid structure formed by ring opening, a carboxylate structure, or a carboxylic acid derivative structure, and a basic compound, and satisfying a specific pH range, has high dispersion stability, can be cured at room temperature to form a cured film, and the cured film has excellent solvent resistance, thus completing the present invention.

[0017] That is, the present invention provides:

[0018] 1. An aqueous dispersion of organopolysiloxane, comprising:

[0019] (A) An organopolysiloxane represented by the following formula (I): 100 parts by mass,

[0020] (B) Basic compounds: amounts that make the pH 7–10, and

[0021] (C) Water: 50–1000 parts by weight

[0022] [Chemistry 1]

[0023]

[0024] (where R) 1 Each of the following is independently a hydrogen atom, or a monovalent saturated hydrocarbon group with 1 to 12 carbon atoms that can be substituted with a halogen atom; an organic group with 2 to 12 carbon atoms that has a free radical polymerizable functional group; an aryl group with 6 to 18 carbon atoms; or an aralkyl group with 7 to 20 carbon atoms; R 2 Each independently represents a monovalent group having a carboxylic anhydride structure, a carboxylic acid structure, or a carboxylate structure, R 3 Each of the following groups independently represents a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, or an isopropyl group. a, b, c, d, and e are each numbers satisfying 0 ≤ a < 1, 0 < b < 1, 0 < c ≤ 0.4, 0 ≤ d < 1, 0 ≤ e < 1, and a + b + c + d + e = 1. f is a number satisfying 0 < f < 4.

[0025] 2. The organopolysiloxane aqueous dispersion according to claim 1, wherein R 2It is a monovalent group having a succinic anhydride structure, a succinic acid structure, or a succinate structure;

[0026] 3. The organopolysiloxane aqueous dispersion according to 1, wherein, in the formula (I), b, d, and e satisfy 0.5 ≤ b < 1, 0 ≤ d < 0.5, and 0 ≤ e < 0.5;

[0027] 4. The organopolysiloxane aqueous dispersion according to 1, wherein the weight-average molecular weight (Mw) of the polystyrene equivalent of component (A) by gel permeation chromatography is 1,000 to 500,000.

[0028] 5. The organopolysiloxane aqueous dispersion according to claim 1, wherein the basic compound of component (B) is an amine compound;

[0029] 6. The organopolysiloxane aqueous dispersion according to claim 1, wherein the amount of surfactant is less than 1% by mass relative to the total mass;

[0030] 7. The organopolysiloxane aqueous dispersion according to claim 1, wherein the amount of organic solvent relative to the total mass is 5% by mass or less;

[0031] 8. A method for manufacturing an aqueous dispersion of organopolysiloxane according to any one of 1 to 7, comprising the following (step α) to (step γ).

[0032] (Step α): A step of co-hydrolyzing and condensing a mixture of silanes comprising a silane compound represented by formula (III) below or its hydrolysate and condensate, and a silane compound represented by formula (IV) below, to obtain an organopolysiloxane having at least one of a cyclic carboxylic anhydride structure or a carboxylic acid structure formed by ring opening thereof.

[0033] R 1 Si(OR 3 3 (III)

[0034] R 4 Si(OR 3 )3 (IV)

[0035] (where R) 1 and R 3 R represents the same meaning as above. 4 Each group independently represents a monovalent group having a cyclic carboxylic anhydride structure.

[0036] (Step β): A step of mixing an organopolysiloxane having at least one of a cyclic carboxylic anhydride structure or a carboxylic acid structure formed by ring opening obtained in (Step α) with a basic compound to obtain a mixture.

[0037] (Step γ): The step of dispersing the mixture obtained in (Step β) in water to obtain an aqueous dispersion of organopolysiloxane;

[0038] 9. A curable organosilicon composition comprising an aqueous dispersion of an organopolysiloxane according to any one of claims 1 to 7;

[0039] 10. A coating agent comprising an aqueous dispersion of an organopolysiloxane according to any one of claims 1 to 7;

[0040] 11. The cured product of the curable organosilicon composition according to claim 9;

[0041] 12. A coated article having a substrate and a cured product according to 11 formed directly or indirectly on at least one side of the substrate by one or more other layers.

[0042] The effects of the invention

[0043] The organopolysiloxane aqueous dispersion of the present invention exhibits excellent dispersion stability and excellent curability. Therefore, curing occurs rapidly even at room temperature, and the resulting cured film has excellent solvent resistance, making it suitable for the manufacture of various coated articles. Detailed Implementation

[0044] The present invention will now be described in detail.

[0045] [1] Aqueous dispersion of organopolysiloxane

[0046] The organopolysiloxane aqueous dispersion of the present invention comprises (A) an organopolysiloxane represented by the following formula (I), (B) an alkaline compound and (C) water, with a pH of 7 to 10.

[0047] (A) Organopolysiloxane

[0048] (A) The organopolysiloxane of component (I) is represented by the following formula (I).

[0049] [Chemistry 2]

[0050]

[0051] In equation (I), R 1 Each of the following is independently a hydrogen atom, or a monovalent saturated hydrocarbon group with 1 to 12 carbon atoms that can be replaced by a halogen atom, an organic group with 2 to 12 carbon atoms that has a free radical polymerizable functional group, an aryl group with 6 to 18 carbon atoms, or an aralkyl group with 7 to 20 carbon atoms.

[0052] As a monovalent saturated hydrocarbon group with 1 to 12 carbon atoms, it can be straight-chain, branched, or cyclic. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, etc. Alkyl groups with 1 to 3 carbon atoms are preferred, and methyl and ethyl groups are more preferred.

[0053] Organic groups with 2 to 12 carbon atoms that are free radical polymerizable functional groups include vinyl, allyl, 3-acryloyloxypropyl, and 3-methacryloyloxypropyl.

[0054] Examples of aryl groups with 6 to 18 carbon atoms include non-substituted aryl groups such as phenyl and naphthyl; alkylaryl groups such as tolyl, xylyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, and dodecylphenyl, with phenyl being preferred.

[0055] Aryl groups with 7 to 20 carbon atoms include benzyl and phenylethyl.

[0056] Furthermore, with regard to the aforementioned alkyl, organic groups, aryl and aralkyl groups, some or all of their hydrogen atoms may be replaced by halogen atoms (fluorine, chlorine, bromine, iodine atoms). Specific examples include chloromethyl, chloropropyl, bromoethyl, trifluoropropyl, chlorophenyl, bromophenyl, etc.

[0057] In equation (I), R 2 Each of these groups is a monovalent group that has a carboxylic anhydride structure, a carboxylic acid structure, or a carboxylate structure.

[0058] Examples of carboxylic anhydride structures include succinic anhydride, maleic anhydride, phthalic anhydride, cyclopentane dicarboxylic anhydride, cyclohexane dicarboxylic anhydride, norbornane dicarboxylic anhydride, and norbornene dicarboxylic anhydride, with succinic anhydride being preferred.

[0059] Examples of carboxylic acid structures include hydrocarbon groups containing one or more carboxyl groups, preferably one to four, and more preferably two carboxyl groups. Specific examples of preferred structures include ring-opening forms of the aforementioned carboxylic anhydride structures such as succinic acid, maleic acid, phthalic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, norbornanedicarboxylic acid, and norbornenedicarboxylic acid, with succinic acid being more preferred.

[0060] In addition, the monovalent group having a carboxylic acid structure may have amide bonds, urethane bonds, urea bonds, etc. As specific examples of such groups, groups represented by the following formulas can be listed.

[0061] [Chemistry 3]

[0062]

[0063] (In the formula, the line with a wavy line represents the bonding end.)

[0064] As carboxylate structures, examples include salts of the carboxyl group contained in the above-mentioned carboxylic acid structures and the basic compounds described later (B), with salts of succinic acid structures and amine compounds being particularly preferred.

[0065] Additionally, in the case of R 2 The structure may include carboxylic anhydride structures and carboxylic acid derivative structures such as carboxamides and carboxylic acid esters generated by reactions with amines, alcohols, etc.

[0066] As R 2 Preferably, the group is represented by the following formula (II).

[0067] [Chemistry 4]

[0068]

[0069] (In the formula, * indicates bonding with silicon atoms.)

[0070] In formula (II), X is a divalent hydrocarbon group with 1 to 40 carbon atoms, which may contain oxygen, nitrogen, sulfur, or silicon atoms, and Z is a straight or branched chain. 1 It is a cyclic carboxylic anhydride structure, or a carboxylic acid structure or carboxylate structure formed by ring opening.

[0071] The divalent hydrocarbon group of X with 1 to 40 carbon atoms is preferably an alkylene group or (poly)oxyalkylene group with 1 to 10 carbon atoms that can be involved by ether bonds, amide bonds, urethane bonds, urea bonds, thioether bonds, etc. More preferably methylene, ethylene, trimethylene, propylene, tetramethylene, hexamethylene, octamethylene, etc., and even more preferably ethylene or trimethylene.

[0072] As Z 1 The cyclic carboxylic anhydride structure can be listed as succinic anhydride, maleic anhydride, phthalic anhydride, cyclopentane dicarboxylic anhydride, cyclohexane dicarboxylic anhydride, norbornene dicarboxylic anhydride, etc., with succinic anhydride structure being preferred.

[0073] In equation (I), R 3 Each of the following can be independently a hydrogen atom, methyl, ethyl, n-propyl, or isopropyl, preferably a hydrogen atom, methyl, or ethyl.

[0074] a, b, c, d, and e are each a number that satisfies 0 ≤ a < 1, 0 < b < 1, 0 < c ≤ 0.4, 0 ≤ d < 1, 0 ≤ e < 1, and a + b + c + d + e = 1.

[0075] Let a be a number that satisfies 0≤a<1. From the perspective of crack suppression effect, a number that satisfies 0≤a≤0.3 is preferred, and a=0 is even more preferred.

[0076] b is a number that satisfies 0 < b < 1. From the perspective of the scratch resistance of the obtained cured product, a number that satisfies 0.5 < b < 1 is preferred.

[0077] c is a number that satisfies 0 < c ≤ 0.4. From the perspective of water dispersion and stability, a number that satisfies 0.03 ≤ c ≤ 0.2 is preferred.

[0078] d is a number that satisfies 0≤d<1. From the viewpoint of the curability of the composition and the hardness of the obtained cured product, it is preferable to satisfy a number that satisfies 0≤d≤0.5, and more preferably 0≤d≤0.2.

[0079] e is a number that satisfies 0≤e<1. From the viewpoint of the curability of the composition and the hardness of the obtained cured product, it is preferable to satisfy a number that satisfies 0≤e≤0.5, and more preferably a number that satisfies 0≤e≤0.2.

[0080] f is a number that satisfies 0 < f < 4. From the viewpoint of the crosslinking density of the cured product, it is preferable to satisfy a number that satisfies 0 < f ≤ 2, and more preferably a number that satisfies 0.1 < f ≤ 1.1.

[0081] (A) The weight-average molecular weight (Mw) of polystyrene converted from the gel permeation chromatography (GPC) of component A is preferably 1,000 to 500,000, more preferably 1,500 to 20,000, and even more preferably 2,000 to 3,000. If the weight-average molecular weight is 1,000 or higher, the aqueous dispersion exhibits excellent storage stability, coatability, and film-forming properties; if it is 500,000 or lower, it can suppress unevenness and non-uniformity during coating.

[0082] Furthermore, the measurement conditions for GPC can be, for example, the methods used in the following examples.

[0083] (B) Basic compounds

[0084] The basic compounds that can be used as component (B) include alkali metal carbonates, alkali metal bicarbonates, alkali metal hydroxides, alkaline earth metal hydroxides, amine compounds, etc., without any particular limitation, but amine compounds are preferred.

[0085] Specific examples of alkali metal carbonates include Na2CO3 and K2CO3.

[0086] Specific examples of alkali metal bicarbonates include NaHCO3 and KHCO3.

[0087] Specific examples of alkali metal hydroxides include NaOH and KOH.

[0088] Specific examples of hydroxides of alkaline earth metals include Ca(OH)2 and Mg(OH)2.

[0089] Specific examples of amine compounds include ammonia, monoethanolamine, diethanolamine, triethanolamine, benzylamine, methylbenzylamine, dimethylbenzylamine, methyldiethanolamine, dimethylethanolamine, triethylamine, tributylamine, dibutylamine, etc.

[0090] The amount of alkaline compound added is such that the pH of the aqueous phase is 7-10, preferably 7-9, and is preferably 0.5-25 parts by mass relative to 100 parts by mass of the organopolysiloxane. If it is 0.5 parts by mass or more, the dispersibility in water is excellent, resulting in an aqueous dispersion with excellent stability; if it is 25 parts by mass or less, the risk of the pH becoming excessively alkaline is low. Furthermore, as shown in the examples below, the pH is a value determined according to JIS Z8802.

[0091] (C) Water

[0092] There are no particular restrictions on the water used, but from the viewpoint of the dispersion stability of aqueous dispersions, it is preferable to use water with a pH of 6 to 8 that has been deionized.

[0093] The amount of water added is 50 to 1000 parts by weight relative to 100 parts by weight of the organopolysiloxane in component (A). If it is less than 50 parts by weight, the stability of the aqueous dispersion may decrease. If it is more than 1000 parts by weight, the film-forming property may be insufficient.

[0094] In the aqueous dispersion of the present invention, solvents miscible with water can be used in conjunction, such as alcohols like methanol, ethanol, and 2-propanol. Furthermore, from an environmental impact perspective, when using organic solvents, their amount relative to the total mass of the aqueous dispersion is preferably greater than 0% by mass and less than 5% by mass.

[0095] From the viewpoint of stability and film-forming properties, it is preferable that the non-volatile component of the aqueous dispersion of the present invention is 5 to 70% by mass relative to the total non-volatile component of the aqueous dispersion. It should be noted that, as shown in the following examples, the non-volatile component is the value measured according to JIS C2133.

[0096] In addition, the aqueous dispersion of the present invention may contain a surfactant. In this case, from the viewpoint of film formation, the amount of surfactant relative to the total aqueous dispersion is preferably greater than 0% by mass and less than 1% by mass.

[0097] [2] Method for manufacturing aqueous dispersions of organopolysiloxanes

[0098] There are no particular limitations on the manufacturing method of the organopolysiloxane aqueous dispersion of the present invention. For example, it can be obtained by a manufacturing method including the following (step α), (step β) and (step γ).

[0099] (Step α): A step of obtaining an organopolysiloxane having at least one of a cyclic carboxylic anhydride structure or a carboxylic acid structure formed by ring opening, by a co-hydrolysis condensation reaction comprising a silane compound represented by formula (III) below or its hydrolysis condensate, and a mixed silane containing a silane compound represented by formula (IV) below.

[0100] R 1 Si(OR 3 3 (III)

[0101] R 4 Si(OR 3 )3 (IV)

[0102] (where R) 1 and R 3 R represents the same meaning as above. 4 Each group is independently a monovalent group with a cyclic carboxylic anhydride structure.

[0103] (Step β): A step of mixing an organopolysiloxane with at least one of the cyclic carboxylic anhydride structure or a carboxylic acid structure obtained in (Step α) above with a basic compound to obtain a mixture.

[0104] (Step γ): The step of dispersing the mixture obtained in (Step β) in water to obtain an aqueous dispersion of organopolysiloxane.

[0105] <(Process α)>

[0106] (Step α) is a step of obtaining an organopolysiloxane having at least one of a cyclic carboxylic anhydride structure or a carboxylic acid structure formed by ring opening of a mixed silane comprising a silane compound represented by formula (III) above or its hydrolysis condensate and a silane compound represented by formula (IV) above through a co-hydrolysis condensation reaction.

[0107] In equation (III), R is... 1 and R 3 Specific examples can be listed as groups that are the same as those exemplified in formula (I) above.

[0108] Specific examples of silane compounds represented by formula (III) above include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, and octadecyltrimethoxysilane. Oxypropylsilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, styryltrimethoxysilane, styryltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, etc.

[0109] In equation (IV) above, R is... 3 Specific examples can be listed as groups that are the same as those exemplified in formula (I) above.

[0110] In equation (IV), R 4 It is a monovalent group having a cyclic carboxylic anhydride structure, preferably a group represented by the following formula (V).

[0111] [Chemistry 5]

[0112]

[0113] (In the formula, * indicates bonding with silicon atoms.)

[0114] In formula (V), X is a divalent hydrocarbon group with 1 to 40 carbon atoms, which may contain oxygen, nitrogen, sulfur, or silicon atoms, and Z is a straight or branched chain. 2 This indicates a cyclic carboxylic anhydride structure.

[0115] The divalent hydrocarbon group of X with 1 to 40 carbon atoms is preferably an alkylene group or (poly)oxyalkylene group with 1 to 10 carbon atoms that can be involved by ether bonds, amide bonds, urethane bonds, urea bonds, thioether bonds, etc., methylene, ethylene, trimethylene, propylene, tetramethylene, hexamethylene, octamethylene, etc., more preferably ethylene or trimethylene.

[0116] As Z 2 The cyclic carboxylic anhydride structure can be listed as succinic anhydride, maleic anhydride, phthalic anhydride, cyclopentane dicarboxylic anhydride, cyclohexane dicarboxylic anhydride, norbornene dicarboxylic anhydride, etc., with succinic anhydride structure being preferred.

[0117] Specific examples of silane compounds represented by the above formula (IV) include 3-trimethoxysilylpropyl succinic anhydride, 3-triethoxysilylpropyl succinic anhydride, 3-trimethoxysilylpropyl phthalic anhydride, 3-triethoxysilylpropyl phthalic anhydride, 3-trimethoxysilylpropyl cyclohexyl dicarboxylic anhydride, and 3-triethoxysilylpropyl cyclohexyl dicarboxylic anhydride.

[0118] The amount of the silane compound represented by the above formula (IV) is 0.4 moles or less relative to the total number of silicon atoms in the mixed silanes, and preferably 0.03 to 0.2 moles from the viewpoint of water dispersibility and stability.

[0119] In step α, the mixed silanes used in the co-hydrolysis condensation reaction may include silane compounds other than those represented by formulas (III) and (IV) above, or their hydrolysis condensates. Specific examples include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethylphenylmethoxysilane, dimethylphenylethoxysilane, and their hydrolysis condensates.

[0120] There are no particular restrictions on the conditions for the hydrolysis-condensation reaction. For example, it can be carried out at 20–150°C for about 0.5–6 hours, preferably at 20–100°C for about 1–4 hours.

[0121] At this point, solvents can be added as needed. Examples of solvents include alcohol solvents such as methanol, ethanol, and isopropanol; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; and aromatic nonpolar solvents such as benzene, toluene, and xylene.

[0122] In addition, an acidic catalyst can be used to promote the hydrolysis reaction. As an acidic catalyst, a strong acid is preferred, and in particular, regardless of the type, sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc., are preferred. From the perspective of ease of post-processing, cation exchange resins having these exchange groups are especially preferred.

[0123] The amount of acidic catalyst added relative to the total mass of the mixed silanes is preferably 100 to 10,000 ppm, more preferably 500 to 3,000 ppm.

[0124] In addition, vacuum distillation can be performed after the hydrolysis reaction. There are no particular restrictions on the conditions for vacuum distillation, but from a stability point of view, it is preferable to carry out the process at 20–120°C for about 0.5–4 hours.

[0125] <(Process β)>

[0126] (Step β) is a step of mixing an organopolysiloxane having a cyclic carboxylic anhydride structure or a carboxylic acid structure obtained in (Step α) with an alkaline compound to obtain a mixture.

[0127] As basic compounds, compounds exemplified as components (B) above can be listed.

[0128] There are no particular restrictions on the conditions for mixing. For example, it is preferable to mix at 20-70°C for 5 minutes to 4 hours, and more preferably at 20-60°C for 10 minutes to 2 hours.

[0129] The amount of alkaline compound added is such that the pH of the aqueous phase after the following (step γ) is 7 to 10, preferably 7 to 9. The amount added is 0.5 to 25 parts by mass relative to 100 parts by mass of organopolysiloxane. If it is more than 0.5 parts by mass, the dispersibility in water is excellent, and an aqueous dispersion with excellent stability is obtained. If it is less than 25 parts by mass, the risk of the pH becoming excessively alkaline is small.

[0130] <(Process γ)>

[0131] (Step γ) is a step to disperse the mixture obtained in (Step β) in water to obtain an aqueous dispersion of organopolysiloxane.

[0132] There are no particular restrictions on the dispersion method; well-known methods can be used. Specific examples include methods using paint shakers, ball mills, homogenizers, etc., at temperatures ranging from 20 to 80°C.

[0133] The amount of water used is 50 to 1000 parts by mass relative to 100 parts by mass of the organopolysiloxane obtained in the above (step α). If it is less than 50 parts by mass, the stability of the aqueous dispersion may decrease. If it is more than 1000 parts by mass, the film-forming property may be insufficient.

[0134] Additionally, after step γ, vacuum distillation can be performed. Vacuum distillation reduces the amount of byproduct alcohols and unreacted low-molecular-weight components in the system. There are no particular limitations on the conditions for vacuum distillation, but from a stability perspective, it is preferable to perform it at approximately 20–120°C for about 0.5–4 hours.

[0135] [3] Curable silicone composition and coating agent

[0136] The aqueous dispersion of the organopolysiloxane of the present invention cures at room temperature or under heating conditions to form a solvent-resistant film, and therefore can be used as a curable organosilicon composition and coating agent. For example, it is preferably used as an exterior wall coating or a primer for coatings, and its use is not particularly limited. Furthermore, in the present invention, "room temperature" means a normal temperature that is neither specially heated nor cooled, meaning a temperature range of 0 to 40°C, preferably 5 to 35°C.

[0137] The curable silicone composition and coating agent of the present invention may contain a waterborne organic resin. Specific examples of waterborne organic resins include, but are not limited to, waterborne acrylic resins, waterborne polyurethane resins, waterborne epoxy resins, waterborne PVA resins, waterborne polyester resins, waterborne alkyd resins, waterborne melamine resins, and waterborne fluoropolymers.

[0138] [4] Cured products and coated articles of curable silicone compositions

[0139] A curable silicone composition is applied to at least one side of a substrate, either directly or through one or more other layers, and cured to form a film, thereby obtaining a coated article having a cured silicone composition on at least one side of the substrate, either directly or through one or more other layers.

[0140] There are no particular limitations on the aforementioned substrates, and examples include glass, silicon wafers, metals, plastic molded bodies, ceramics, and composites thereof.

[0141] Furthermore, regarding the surface of these substrates, chemical forming treatment, corona discharge treatment, plasma treatment, substrates treated with acid or alkali solutions, and decorative plywood coated with a type of paint different from the main substrate can also be used. Other layers include those obtained by coating with polyester resin, polyurethane resin, amino alkyd resin, paint, spray coating, and water-based wax.

[0142] As for the coating method on the substrate, any known method can be appropriately selected, such as roller coating, bar coating, wire rod coating, spraying, flow coating, spin coating, curtain coating, doctor blade coating, dip coating, brush coating, and other coating methods. There is no particular limitation on the coating amount, but it is generally preferred to have a thickness of 0.1 to 1000 μm after drying, and more preferably 1 to 100 μm.

[0143] Methods for curing the curable silicone composition of the present invention include room temperature curing and heat curing. There are no particular limitations on the heating temperature; curing at 80–150°C for a short time of about 5–60 minutes yields a transparent cured product. Furthermore, the cured product preferably does not discolor even after post-curing at 150–180°C for about 30 minutes to 3 hours, exhibiting excellent transparency.

[0144] Example

[0145] The following examples, embodiments, and comparative examples illustrate the invention in more detail, but the invention is not limited to the following embodiments.

[0146] Furthermore, the average composition of the organopolysiloxane was determined using an NMR measuring device manufactured by Nippon Electronics Co., Ltd. 1 H-NMR and 29 The value is calculated from the integrated value of the Si-NMR spectrum, and the weight-average molecular weight (Mw) is the polystyrene conversion value obtained by GPC (gel permeation chromatography) under the following conditions.

[0147] [GPC Conditions]

[0148] Device: HLC-8220 (manufactured by Tosoh Corporation)

[0149] Column: TSKgel GMHXL-L, TSKgel G4000HXL, TSKgel G2000HXL X2

[0150] Elution solvent: Tetrahydrofuran (THF)

[0151] Flow rate: 1 mL / min

[0152] Detector: RI

[0153] Column constant temperature bath temperature: 40℃

[0154] Standard material: polystyrene

[0155] [1] Manufacturing of organopolysiloxanes

[0156] [Synthesis example 1]

[0157] In a 500 mL detachable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 16.2 g (0.1 mol) of hexamethyldisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), 123.8 g (0.8 mol) of methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM-13), 7.9 g (0.03 mol) of 3-trimethoxysilylpropylsuccinic anhydride (manufactured by Shin-Etsu Chemical Industry Co., Ltd., X-12-967C) and 15 g of isopropanol (IPA) were stirred in a reactor. When the mixture became homogeneous, 30 g of deionized water was added. After stirring at 80 °C for 2 hours, the alcohol was removed by vacuum distillation (50 °C, 120 mmHg) to obtain a high-viscosity liquid. The weight-average molecular weight of the organopolysiloxane component in the obtained liquid is 2500, which is represented by a=0, b=0.78, c=0.03, d=0, e=0.19, and f=0.2 in formula (I).

[0158] [Synthesis example 2]

[0159] In Synthesis Example 1, except that 12.2 g (0.1 mol) of hexamethyldisiloxane was converted to dimethyldimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), a high-viscosity liquid was obtained by following the same steps as in Synthesis Example 1. The weight-average molecular weight of the organopolysiloxane component in the obtained liquid was 3000, represented by a=0, b=0.86, c=0.03, d=0.11, e=0, and f=0.3 in Formula (I).

[0160] [Synthesis example 3]

[0161] In a 500 mL detachable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 108.4 g (0.7 mol) of methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-13), 10.5 g (0.05 mol) of 3-trimethoxysilylpropylsuccinic anhydride (manufactured by Shin-Etsu Chemical Co., Ltd., X-12-967C) and 17 g of IPA were stirred in a reactor. When the mixture became homogeneous, 30 g of deionized water was added. After stirring at 80 °C for 2 hours, 39.7 g (0.2 mol) of phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added. The alcohol was removed by vacuum distillation (50 °C, 120 mmHg) to obtain a high-viscosity liquid. The weight-average molecular weight of the organopolysiloxane component in the obtained liquid is 2200, which is represented by a=0, b=0.95, c=0.05, d=0, e=0, and f=0.5 in formula (I).

[0162] [Synthesis Example 4]

[0163] In a 500 mL detachable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 10.6 g (0.07 mol) of hexamethyldisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), 80.5 g (0.56 mol) of methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM-13), 37.5 g (0.14 mol) of 3-trimethoxysilylpropylsuccinic anhydride (manufactured by Shin-Etsu Chemical Industry Co., Ltd., X-12-967C) and 15 g of IPA were stirred in a reactor. When the mixture became homogeneous, 30 g of deionized water was added. After stirring at 80 °C for 2 hours, the alcohol was removed by vacuum distillation (50 °C, 120 mmHg) to obtain a high-viscosity liquid. The weight-average molecular weight of the organopolysiloxane component in the liquid is 2500, represented by a=0, b=0.67, c=0.16, d=0, e=0.17, and f=0.4 in formula (I).

[0164] [Synthesis example 5]

[0165] In a 500 mL detachable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 12.0 g (0.1 mol) of dimethyldimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), 39.7 g (0.2 mol) of phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM-103), 17.4 g (0.05 mol) of the compound represented by the following formula (1) and 15 g of IPA were stirred in a reactor. When the mixture became homogeneous, 10 g of deionized water was added. After stirring at 80 °C for 2 hours, the alcohol was removed by vacuum distillation (50 °C, 120 mmHg) to obtain a high-viscosity liquid. The weight-average molecular weight of the organopolysiloxane component in the liquid was 1500, represented by a=0, b=0.55, c=0.14, d=0.21, e=0, and f=0.4 in formula (I).

[0166] [Chemistry 6]

[0167]

[0168] (In the formula, Et represents ethyl.)

[0169] [Comparative Synthesis Example 1]

[0170] In a 500 mL detachable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 19.5 g (0.12 mol) of hexamethyldisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), 148.6 g (0.96 mol) of methyltrimethoxysilane: KBM-13 (manufactured by Shin-Etsu Chemical Co., Ltd.), and 17 g of IPA were stirred in a reactor. When the mixture became homogeneous, 35 g of deionized water was added. After stirring at 80°C for 2 hours, the alcohol was removed by vacuum distillation (50°C, 120 mmHg), resulting in a high-viscosity liquid. The weight-average molecular weight of the organopolysiloxane component in the obtained liquid was 2500, represented by a=0, b=0.80, c=0, d=0, e=0.20, and f=0.3 in formula (I).

[0171] [Comparative Synthesis Example 2]

[0172] In a 500 mL detachable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 16.2 g (0.1 mol) of hexamethyldisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), 123.8 g (0.8 mol) of methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-13), 25.7 g (0.05 mol) of 50% methanol solution of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 15 g of isopropanol (IPA) were stirred in a reactor. When the mixture became homogeneous, 30 g of 1N hydrochloric acid was added. After stirring at 80 °C for 2 hours, 5 g (0.08 mol) of propylene oxide was added, and the alcohol was removed by vacuum distillation (50 °C, 120 mmHg) to obtain a high-viscosity liquid. The weight-average molecular weight of the organopolysiloxane component in the obtained liquid is 2900, which is represented by a=0, b=0.78, c=0, d=0, e=0.19, and f=0.2 in formula (I).

[0173] [2] Manufacturing of Curable Organosilicon Compositions (Aqueous Dispersions of Organopolysiloxanes)

[0174] [Examples 1-1 to 1-8, Comparative Examples 1-1 to 1-8]

[0175] The organopolysiloxanes and basic compounds obtained in Synthetic Examples 1-5 and Comparative Synthetic Examples 1 and 2 were stirred at 25°C for 30 minutes using the proportions (parts by mass) shown in Tables 1 and 2. The diluted solvent was then stirred and mixed, and the mixture was subjected to vacuum distillation (50°C, 140 mmHg) for 2 hours to produce curable organosilicon compositions.

[0176] The non-volatile components, pH, appearance, and stability of the obtained curable silicone compositions were determined using the following methods. The results are presented in Tables 1 and 2.

[0177] (1) Non-volatile components

[0178] Measured according to JIS C2133.

[0179] (2) pH

[0180] Measured according to JIS Z8802.

[0181] (3) Appearance

[0182] When the composition is sealed in a container and left to stand at 25°C for 24 hours, cases where clear separation and insolubility are observed are evaluated as ×, and cases where no separation is observed and a uniform dispersion is maintained are evaluated as ○.

[0183] (4) Stability

[0184] When the composition is sealed in a container and left to stand at 50°C for 3 days, a situation where no significant increase in viscosity or gelation is observed is evaluated as ○, and a situation where a significant increase in viscosity or gelation is observed is evaluated as ×.

[0185] [Table 1]

[0186]

[0187] [Table 2]

[0188]

[0189] [3] Production of covered items

[0190] [Examples 2-1 to 2-8, Comparative Examples 2-1 to 2-8]

[0191] Using flow coating, the aqueous dispersions of organopolysiloxanes obtained in Examples 1-1 to 1-8 and Comparative Examples 1-3, 1-4, and 1-8, as well as the MIBK solutions of organopolysiloxanes obtained in Comparative Examples 1-6 and 1-7, were coated onto an aluminum substrate.

[0192] After drying at 100°C for 10 minutes, the material was allowed to cure at 25°C for 3 days, resulting in a coated article with a cured film formed on the surface of an aluminum substrate. The coated article was subjected to friction testing and pencil hardness measurement using the methods described below. The results are shown in Table 3.

[0193] (1) Friction test

[0194] Acetone and toluene were respectively impregnated in Bemcot M-3II (manufactured by Asahi Kasei Corporation, with an area of ​​4 cm²). 2The surface was rubbed 30 times under a load of 500g, and the appearance of the coating was visually evaluated. After rubbing with acetone and toluene, cases where no change was found compared to the appearance of the coating before the test were marked as "〇"; cases where no change was found after rubbing with toluene but peeling or whitening of the coating was found after rubbing with acetone were marked as "△"; and cases where peeling or whitening of the coating was found after testing with acetone and toluene were marked as "×".

[0195] (2) Pencil hardness

[0196] The test was conducted according to JIS K5600-5-4 under a load of 750g. Furthermore, damage detected using a 6B pencil is recorded as <6B.

[0197] [Table 3]

[0198]

[0199] As shown in Tables 1-3, it can be seen that the curable organosilicon compositions (organopolysiloxane aqueous dispersions) of Examples 1-1 to 1-8 are in a stable dispersion state in water, and the resulting cured films have excellent solvent resistance.

[0200] On the other hand, it can be seen that in Comparative Example 1-1, where the organopolysiloxane was replaced with an organopolysiloxane that does not have a carboxylic anhydride and carboxylic acid structure, and in Comparative Example 1-2, where the amount of alkaline compound added was small and the pH was less than 7, an aqueous dispersion could not be obtained.

[0201] Furthermore, in Comparative Examples 1-3 (pH exceeding 10) and 1-4 (low water content), it was found that while there were no issues with the solvent resistance and hardness of the cured films, the stability of the aqueous dispersions was poor. Additionally, it was found that while no problems were observed with the cured films in Comparative Examples 1-5 (where water was replaced with methyl isobutyl ketone (MIBK) in Example 1-1), the stability of the liquid was low.

[0202] Furthermore, it is known that Comparative Examples 1-6 and 1-7, which are MIBK solutions made without alkaline compounds and containing organopolysiloxanes, did not have any problems with the stability of the liquid, but the resulting films were in an under-cured state, with significantly poor solvent resistance and hardness.

[0203] Furthermore, the organopolysiloxane aqueous dispersions with quaternary ammonium salt structures in Comparative Examples 1-8, although exhibiting high liquid stability, have poor curability, resulting in films with low solvent resistance and hardness.

Claims

1. An aqueous dispersion of organopolysiloxane, comprising: (A) An organopolysiloxane represented by the following formula (I): 100 parts by mass, (B) Basic compounds: amounts that make the pH 7–10, and (C) Water: 50–1000 parts by weight [Chemistry 1] In the formula, R 1 Each of the following is independently a hydrogen atom, or a monovalent saturated hydrocarbon group with 1 to 12 carbon atoms that can be substituted with a halogen atom; an organic group with 2 to 12 carbon atoms that has a free radical polymerizable functional group; an aryl group with 6 to 18 carbon atoms; or an aralkyl group with 7 to 20 carbon atoms; R 2 Each independently represents a monovalent group having a carboxylic anhydride structure, a carboxylic acid structure, or a carboxylate structure, R 3 Each of the following can independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, or an isopropyl group. a, b, c, d, and e are each numbers that satisfy 0 ≤ a < 1, 0 < b < 1, 0 < c ≤ 0.4, 0 ≤ d < 1, 0 ≤ e < 1 and a + b + c + d + e = 1. f is a number that satisfies 0 < f < 4.

2. The organopolysiloxane aqueous dispersion according to claim 1, wherein, The R 2 It is a monovalent group having a succinic anhydride structure, a succinic acid structure, or a succinate structure.

3. The organopolysiloxane aqueous dispersion according to claim 1, wherein, In equation (I), b, d, and e satisfy 0.5 ≤ b < 1, 0 ≤ d < 0.5, and 0 ≤ e < 0.

5.

4. The organopolysiloxane aqueous dispersion according to claim 1, wherein, The weight-average molecular weight (Mw) of polystyrene converted from the gel permeation chromatography of component (A) is 1,000 to 500,000.

5. The organopolysiloxane aqueous dispersion according to claim 1, wherein, The basic compound of component (B) is an amine compound.

6. The organopolysiloxane aqueous dispersion according to claim 1, wherein, The amount of surfactant is less than 1% by mass relative to the total mass.

7. The organopolysiloxane aqueous dispersion according to claim 1, wherein, The amount of organic solvent is less than 5% by mass relative to the total mass.

8. A method for manufacturing an aqueous dispersion of organopolysiloxane according to any one of claims 1 to 7, comprising the following steps (α) to (γ). (Step α): A step of co-hydrolyzing and condensing a mixture of silanes comprising a silane compound represented by formula (III) below or its hydrolysate and condensate, and a silane compound represented by formula (IV) below, to obtain an organopolysiloxane having at least one of a cyclic carboxylic anhydride structure or a carboxylic acid structure formed by ring opening thereof. R 1 Si(OR 3 )3 (III) R 4 Si(OR 3 )3 (IV) In the formula, R 1 and R 3 R represents the same meaning as above. 4 Each of these groups independently represents a monovalent group having a cyclic carboxylic anhydride structure. (Step β): A step of mixing an organopolysiloxane having at least one of a cyclic carboxylic anhydride structure or a carboxylic acid structure formed by ring opening obtained in (Step α) with a basic compound to obtain a mixture. (Step γ): The step of dispersing the mixture obtained in (Step β) in water to obtain an aqueous dispersion of organopolysiloxane.

9. A curable organosilicon composition comprising an aqueous dispersion of an organopolysiloxane according to any one of claims 1 to 7.

10. A coating agent comprising an aqueous dispersion of an organopolysiloxane according to any one of claims 1 to 7.

11. The cured product of the curable organosilicon composition according to claim 9.

12. A coated article having a substrate and a cured product according to claim 11 formed directly or indirectly on at least one side of the substrate by one or more other layers.

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