Organopolysiloxane, method for producing same, adhesive agent, aqueous coating composition, and primer composition

Abstract

Provided is a water-soluble organopolysiloxane which is represented by formula (1) and has excellent storage stability. # imgabs0 # (In the formula, R1 is a C1-10 monovalent hydrocarbon group, R2 is each independently a C1-10 monovalent hydrocarbon group which may be substituted by a glycidoxy group, R3 is a C1-6 monovalent saturated hydrocarbon group, at least a portion of R3 is a C3-6 monovalent saturated hydrocarbon group, a, b, c, and d are numbers satisfying a > = 0.5, b > = 0, c > = 0, d > = 0, and a + b + c + d = 1, and x and y are numbers satisfying x > = 1 and 0 < y < = 0.5. )

Description

Technical Field

[0001] The present invention relates to an organopolysiloxane, a method for producing the same, an adhesion promoter, an aqueous coating composition, and a primer composition. More specifically, the present invention relates to an organopolysiloxane containing a siloxane unit having 3-glycidoxypropyl as a constituent unit and having a silanol group, a method for producing the organopolysiloxane, an adhesion promoter composed of the organopolysiloxane, an aqueous coating composition containing the organopolysiloxane, and a primer composition. Background Art

[0002] A compound having two or more different reactive functional groups in one molecule is known as a coupling agent for bonding different types of materials. Among them, a silane coupling agent having a hydrolyzable silyl group such as an alkoxysilyl group as one of the reactive groups and also having various organic reactive groups such as a primary amino group, a secondary amino group, a glycidyl ether group, a methacryloyl group, a ureido group, a vinyl group, a mercapto group, and an isocyanate group is known as a primer for improving the adhesion of a coating material, and is also known as an adhesion promoter added to a coating composition.

[0003] In addition, compositions containing a reactive organopolysiloxane obtained by hydrolyzing and condensing a silane coupling agent as a monomer have been reported. For example, in Patent Document 1, a coating material and an adhesive sheet containing an organosilicon sesquioxide having an epoxy group are proposed, and in Patent Documents 2 to 4, a low molecular weight oligomer obtained by partially hydrolyzing and condensing a silane coupling agent having an epoxy group is proposed as an adhesion improver.

[0004] Compared with a silane coupling agent, the advantages of using an oligomer and / or polymer obtained by hydrolyzing and condensing it include, first, the advantage that the concern about the reduction of the active ingredient in processes such as drying can be eliminated because of the high molecular weight and low volatility.

[0005] In addition, the advantage of a small amount of generation of volatile organic compounds (VOCs) can be cited. From the viewpoint of reducing the environmental burden such as the water-based and solvent-free conversion of current solvent-based coatings, compared with a silane coupling agent that generates alcohol by hydrolysis, the amount of alcohol generated per unit mass of the active ingredient of a pre-partially hydrolyzed oligomer is reduced, and it can be said to be a material suitable for such requirements.

[0006] In order to further reduce VOCs, an aqueous solution of a hydrolysis condensate obtained by completely hydrolyzing a silane coupling agent and removing the generated alcohol has also been proposed. In Patent Documents 5 to 7, an aqueous silane composition containing a hydrolysis condensate having a functional group such as an amino group, a mercapto group, and a carboxyl group is proposed, and in Patent Document 8, an aqueous silane composition containing a hydrolysis condensate having an ethylene glycol group is proposed.

[0007] Such aqueous silane compositions are all hydrolysis condensates of silane coupling agents with high activity. From the viewpoints of handling and stability, they must be made into aqueous solutions, but their storage stability is insufficient.

[0008] Prior art documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-143161

[0011] Patent Document 2: International Publication No. 2018 / 34232

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 2018-127507

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 2022-27097

[0014] Patent Document 5: European Patent No. 0675128 Specification

[0015] Patent Document 6: Japanese Patent Application Laid-Open No. 2016-44278

[0016] Patent Document 7: Japanese Patent Application Laid-Open No. 2015-34097

[0017] Patent Document 8: Japanese Patent Application Laid-Open No. 2017-114852 Summary of the invention

[0018] Problems to be solved by the invention

[0019] In view of the above actual situation, the present invention has been completed, and the object is to provide a water-soluble organopolysiloxane having an organic functional group and excellent storage stability.

[0020] Means for solving the problems

[0021] The inventors of the present invention conducted in-depth research to solve the above problems and found that: an organopolysiloxane having a specific amount of siloxane units having 3-glycidoxypropyl and having a silanol group has excellent storage stability, and also found that an aqueous composition containing the organopolysiloxane has excellent adhesion and is suitable as a primer, thus completing the present invention.

[0022] That is, the present invention provides:

[0023] 1. An organopolysiloxane represented by the following formula (1),

[0024] [Chemical formula 1]

[0025]

[0026] (In the formula, R 1is a monovalent hydrocarbon group having 1 to 10 carbon atoms, R 2 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a glycidyloxy group, R 3 is a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, R 3 at least a part of which is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms, a, b, c, d are numbers satisfying a≥0.5, b≥0, c≥0, d≥0, and a + b + c + d = 1, and x, y are numbers satisfying x≥1, 0<y≤0.5.)

[0027] 2. The organopolysiloxane according to 1, wherein R 3 is a monovalent saturated hydrocarbon group having 3 or 4 carbon atoms.

[0028] 3. The organopolysiloxane according to 1 or 2, wherein b, c, d, y are numbers satisfying b = 0, c = 0, d = 0, 0.01≤y≤0.1.

[0029] 4. A method for producing an organopolysiloxane, which is a method for producing the organopolysiloxane according to any one of 1 to 3, comprising a silane compound containing 3-glycidyloxypropyl represented by the following formula (i), and an optionally used silane compound represented by the following formula (ii), a silane compound represented by the following formula (iii), and any one or more silane monomers of the silane compound represented by the following formula (iv), in the presence of an alcohol represented by the following formula (v), relative to 1 mole of the Si(OR) group (R is a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms) of the silane monomer, 0.8 to 1.1 times the molar amount of water is added, and the (co)hydrolysis condensation reaction of the silane monomer is carried out under acidic conditions,

[0030] [Chemical formula 2]

[0031]

[0032] (In the formula, R 1 , R 2 and R are the same as above, and R 0 is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms.)

[0033] 5. An adhesion promoter, which contains the organopolysiloxane according to any one of 1 to 3.

[0034] 6. An aqueous coating composition, which contains the organopolysiloxane according to any one of 1 to 3.

[0035] 7. A primer composition, which contains the organopolysiloxane according to any one of 1 to 3.

[0036] Effects of the Invention

[0037] The organopolysiloxane of the present invention has reactive epoxy groups, exhibits excellent effects in modifying organic resins and enhancing adhesion to resin substrates, and has excellent stability, thus enabling an extended service life. In addition, the organopolysiloxane of the present invention has silanol groups, so it has excellent reactivity with inorganic substrates. Moreover, it shows high water solubility and can be used as an additive in aqueous coating compositions. Description of the Drawings

[0038] Figure 1 1H-NMR spectrum of the organopolysiloxane Ep1 obtained in Example 1-1 1 1H-NMR spectrum. Detailed Description of the Invention

[0039] The present invention will be specifically described below.

[0040] (1) Organopolysiloxane

[0041] The organopolysiloxane according to the present invention is represented by the following general formula (1).

[0042] [Chemical Formula 3]

[0043]

[0044] In the above formula, R 1 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, which can be linear, branched or cyclic. Specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, and n-decyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; alkenyl groups such as vinyl, allyl, butenyl, hexenyl, and octenyl; and aryl groups such as phenyl and naphthyl. Among these, methyl, ethyl, n-propyl, and phenyl are preferred, methyl and ethyl are more preferred, and methyl is further preferred.

[0045] R 2 each independently represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, which can be substituted with a glycidyloxy group. Specific examples thereof include the same groups as those exemplified for R 1 above and glycidyloxy-substituted alkyl groups such as glycidyloxypropyl. Among these, methyl, ethyl, n-propyl, glycidyloxypropyl, and phenyl are preferred, methyl and ethyl are more preferred, and methyl is further preferred.

[0046] R 3 is a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, which can be linear, branched or cyclic. Specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, and n-hexyl; and cycloalkyl groups such as cyclohexyl.

[0047] Regarding the organopolysiloxane of the present invention, from the viewpoint of stability, at least a part of R 3 , preferably all of R 3 is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms, preferably a monovalent saturated hydrocarbon group having 3 or 4 carbon atoms, more preferably a branched alkyl group having 3 or 4 carbon atoms, and still more preferably isopropyl or isobutyl.

[0048] a, b, c, and d represent the molar ratios of the respective siloxane units and are numbers satisfying a + b + c + d = 1.

[0049] a is a number of 0.5 or more, preferably a number of 0.5 to 1. If a is less than 0.5, the amount of effective epoxy groups decreases, and the effect of improving the adhesion cannot be expected. In addition, the organopolysiloxane represented by the formula (1) becomes high-viscosity, gum-like or solid-like, and has poor processability and reduced water solubility.

[0050] b is a number of 0 or more, preferably a number of 0 to 0.5, and preferably 0 from the aspect of the amount of epoxy groups contained in the organopolysiloxane of the present invention.

[0051] c is a number of 0 or more, preferably a number of 0 to 0.5. From the aspect of the reactivity of epoxy groups, 0 is preferred.

[0052] d is a number of 0 or more, preferably a number of 0 to 0.5, and preferably 0 from the aspect of storage stability.

[0053] x and y each represent the number of moles of hydroxyl groups and alkoxy groups bonded to 1 mole of Si atoms.

[0054] x is a number of 1 or more, and preferably a number of 1 to 2 from the aspect of storage stability. If it is less than 1, the water solubility of the organopolysiloxane and the reactivity with inorganic substrates are poor.

[0055] y is a number satisfying 0 < y ≤ 0.5, preferably a number satisfying 0 < y ≤ 0.3, and more preferably 0.01 ≤ y ≤ 0.1 from the aspect of reducing the alcohol generated by hydrolysis. When y is 0, although the organopolysiloxane of the present invention is a material with little environmental burden that basically does not generate alcohol, due to the high reactivity of the silanol groups, there are problems of insufficient storage stability and inapplicability to practical use. By containing the monovalent saturated hydrocarbon group having 3 to 6 carbon atoms in the above R 3 , the reactivity of the active silanol groups can be controlled, and an improvement in the desired storage stability can be expected.

[0056] As the organopolysiloxane of the present invention, an organopolysiloxane represented by the following formula (1a) is preferred.

[0057] [Chemical formula 4]

[0058]

[0059] In formula (1a), R 3 is the same as above, a1 = 1, and x1 and y1 are numbers satisfying x1 ≥ 1 and 0.01 ≤ y ≤ 0.1.

[0060] From the viewpoints of water solubility and processability, the weight-average molecular weight of the organopolysiloxane of the present invention is preferably 500 to 10,000, more preferably 500 to 1,000. Further, the weight-average molecular weight in the present invention is a standard polystyrene conversion value obtained by gel permeation chromatography (GPC).

[0061] In addition, the kinematic viscosity of the organopolysiloxane of the present invention is preferably 100 to 500 mm 2 / s, more preferably 200 to 450 mm 2 / s. Further, the kinematic viscosity is the value at 25°C measured using a Cannon-Fenske viscometer.

[0062] The contents of water and free alcohol as impurities in the organopolysiloxane of the present invention are each preferably 1% by mass or less. Water does not belong to VOC, but when it is present in excess, since it can react with epoxy groups, it is desirable to contain as little water as possible when storing the organopolysiloxane of the present invention for a long time.

[0063] (2) Method for producing organopolysiloxane

[0064] There is no particular limitation on the method for producing the organopolysiloxane of the present invention. For example, it can be produced by (co)hydrolytic condensation of any one or two or more silane monomers including silane compounds containing 3-glycidoxypropyl such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane represented by the following formula (i), optionally used silane compounds represented by the following formula (ii), silane compounds represented by the following formula (iii), and silane compounds represented by the following formula (iv) in the presence of an alcohol having 3 to 6 carbon atoms represented by the following formula (v) under acidic conditions.

[0065] [Chemical formula 5]

[0066]

[0067] In the above formulas, R 1 and R 2 are the same as above.

[0068] Each R is independently a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, which may be linear, branched, or cyclic. Specific examples thereof include the same groups as those exemplified for R 3 . Among them, methyl and ethyl are preferred.

[0069] R 0 is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms, preferably 3 or 4 carbon atoms. As the monovalent saturated hydrocarbon group of R 0 , it can be linear, branched or cyclic. As specific examples thereof, groups similar to the groups having 3 to 6 carbon atoms among the groups exemplified for R 3 can be cited. Among them, a branched monovalent saturated hydrocarbon group having 3 or 4 carbon atoms is preferred, a branched alkyl group having 3 or 4 carbon atoms is more preferred, and isopropyl and isobutyl are further preferred.

[0070] As specific examples of the silane compound containing 3-glycidoxypropyl represented by the above formula (i), in addition to 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, etc. can be cited.

[0071] As specific examples of the silane compound represented by the above formula (ii), methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, etc., trialkoxysilanes, etc. can be cited.

[0072] As specific examples of the silane compound represented by the above formula (iii), dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, cyclopentylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methyloctyldimethoxysilane, etc., dialkoxysilanes, etc. can be cited.

[0073] As specific examples of the silane compound represented by the above formula (iv), tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, etc., tetraalkoxysilanes, etc. can be cited.

[0074] In addition, hydrolysis condensates thereof can also be used. These can be used alone or in combination of two or more.

[0075] Preferably, the usage amounts of these silane monomers are adjusted according to the molar ratios (the values of a to d in the formula (1)) of the respective siloxane units of the organopolysiloxane constituting the target.

[0076] Examples of the alcohol represented by the above formula (v) include n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, pentanol, neopentanol, hexanol, cyclohexanol, etc. Alcohols having 3 or 4 carbon atoms are preferred, and isopropanol and isobutanol are more preferred.

[0077] The addition amount of the alcohol is preferably 0.1 to 5 moles, more preferably 0.5 to 2 moles, per 1 mole of the silane monomer.

[0078] From the viewpoints of suppressing the reaction with the epoxy group and reducing the remaining alkoxysilyl groups such as Si(OR) groups (R is the same as above. The same applies hereinafter), the amount of water used in the hydrolysis of the above silane monomer is 0.8 to 1.1 times the molar amount, preferably 1 to 1.1 times the molar amount, per 1 mole of the alkoxysilyl group such as Si(OR) group.

[0079] The acid component adjusted to acidic conditions during the hydrolysis reaction is not particularly limited as long as it is a commercially available Bronsted acid. From the viewpoint of ease of acquisition, formic acid, acetic acid, citric acid, hydrochloric acid, and nitric acid are preferred. From the viewpoint of suppressing the increase in the molecular weight of the obtained organopolysiloxane due to excessive dehydration condensation reaction between silanols and the decrease in the amount of silanol groups resulting in reduced water solubility, the usage amount of the acid is preferably 0.0001 to 0.01 moles per 1 mole of the silane monomer.

[0080] In the hydrolysis reaction, organic solvents other than alcohols can be used as needed within a range that does not hinder the reaction. As the organic solvents that can be used, organic solvents compatible with water as a reaction raw material are preferred, and esters, ketones, ethers, etc. are preferred. In addition, considering the distillation conditions for removing the generated alcohol, it is preferred that the boiling point of the organic solvent is low, and a solvent having a boiling point of 150°C or lower under atmospheric pressure is preferred.

[0081] Specific examples of the esters include ethyl acetate, butyl acetate, etc.

[0082] Specific examples of the ketones include acetone, methyl ethyl ketone, cyclohexanone, etc.

[0083] Specific examples of the ethers include tetrahydrofuran, tetrahydropyran, dioxane, etc.

[0084] The temperature of the hydrolysis reaction is preferably 55 to 70°C, and the reaction time is preferably 1 to 5 hours.

[0085] In addition, after the hydrolysis reaction of the silane monomer, the following steps are preferably carried out: under reduced pressure, water, the alcohol generated by the hydrolysis of the alkoxysilyl group, and the above-mentioned organic solvent are distilled off in the temperature range of 30 to 80 °C.

[0086] The organopolysiloxane of the present invention can be used as an adhesion-imparting agent for curable compositions such as coatings. In addition, since it has excellent water solubility, it can be made into an aqueous coating composition.

[0087] (3) Aqueous coating composition

[0088] The aqueous coating composition of the present invention contains the above-mentioned organopolysiloxane. As the above-mentioned organopolysiloxane, one kind can be used alone, or two or more kinds can be used in combination.

[0089] The aqueous coating composition of the present invention preferably contains water as a solvent. In particular, it is preferably an aqueous solution containing only water as a solvent. The blending amount of the above-mentioned organopolysiloxane in the composition is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

[0090] As specific examples of the aqueous coating composition, there can be mentioned compositions containing an aqueous resin such as an aqueous epoxy resin composition and an aqueous polyurethane resin composition. As one of the components of these aqueous resin compositions, the organopolysiloxane of the present invention can be used.

[0091] As specific examples of the aqueous resin, in addition to the aqueous epoxy resin and the aqueous polyurethane resin, there can be mentioned an aqueous polyester resin, an aqueous acrylic resin, and the like.

[0092] In addition, the aqueous coating composition of the present invention can contain any additives such as an organic solvent, an antioxidant, an ultraviolet absorber, a light stabilizer, a thickener, a dispersant, and an adhesion promoter within the range that does not hinder the effects of the present invention.

[0093] There is no particular limitation on the method for producing the aqueous coating composition of the present invention. For example, there can be mentioned a method of mixing the above-mentioned organopolysiloxane, a solvent, an optionally used aqueous resin, and other additives according to a conventional method.

[0094] By directly applying the obtained aqueous coating composition or applying it via other layers such as a primer layer onto a specified substrate and drying it for 1 to 60 minutes in an environment of 20 to 50 °C and 30 to 60% RH, a coating film can be formed.

[0095] As the substrate, there is no particular limitation, and examples thereof include a plastic molded body, a wood-based product, ceramics, glass, metal, and a composite thereof.

[0096] As a coating method of the aqueous coating composition, there is no particular limitation, and it can be appropriately selected from conventionally well-known methods. For example, various coating methods such as brushing, wiping, spraying, dipping, bar coating, flow coating, roll coating, curtain coating, spin coating, and knife coating can be cited.

[0097] (4) Primer composition

[0098] The organopolysiloxane of the present invention can be suitably used as a coupling component or an aqueous reactive binder in an aqueous primer composition (coating).

[0099] The primer composition of the present invention contains the above organopolysiloxane. As the above organopolysiloxane, one kind can be used alone, or two or more kinds can be used in combination.

[0100] In addition, the primer composition of the present invention preferably contains water as a solvent. In particular, an aqueous solution containing only water as a solvent is preferred. The compounding amount of the above organopolysiloxane in the composition is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

[0101] Furthermore, the primer composition of the present invention may contain optional additives within a range that does not hinder the effects of the present invention. As specific examples thereof, the same additives as those exemplified in the aqueous coating composition can be cited.

[0102] There is no particular limitation on the manufacturing method of the primer composition of the present invention and the method for forming the primer layer, and the same methods as those for the aqueous coating composition can be cited respectively.

[0103] In addition, other layers can be formed on the surface of the primer layer. As other layers, for example, a coating layer composed of a cured film of an aqueous resin composition containing an aqueous acrylic resin, an aqueous polyester resin, an aqueous epoxy resin, an aqueous polyurethane resin, etc. can be cited. Among these, a coating layer composed of a cured film of an aqueous polyurethane resin composition is preferred. The method for forming the coating layer can also be cited as the same method as that for the aqueous coating composition.

[0104] Examples

[0105] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited to these examples. Furthermore, in the following examples, unless otherwise specified, "parts" and "%" respectively mean "parts by mass" and "% by mass". In addition, the GPC measurement and proton nuclear magnetic resonance spectroscopy ( 1 1H-NMR) measurement conditions are as described below, and the kinematic viscosity is the value at 25°C measured using a Cannon-Fenske viscometer.

[0106] (1) GPC measurement conditions

[0107] Apparatus: HLC-8320GPC manufactured by Tosoh Corporation

[0108] Elution solvent: Tetrahydrofuran (THF)

[0109] Flow rate: 0.6 mL / min

[0110] Detector: Differential refractive index detector (RI)

[0111] Column: TSK Guardcolumn SuperH-H

[0112] TSKgel SuperHM-N (6.0 mm I.D. × 15 cm × 1)

[0113] TSKgel SuperH2500 (6.0 mm I.D. × 15 cm × 1)

[0114] (All are manufactured by Tosoh Corporation)

[0115] Column temperature: 40 °C

[0116] Sample injection volume: 50 μL (THF solution with a concentration of 2.0%)

[0117] Standard: Monodisperse polystyrene

[0118] (2) 1 1H-NMR measurement conditions

[0119] Apparatus: AVANCE III 400 manufactured by BURKER

[0120] Solvent: CDCl 3

[0121] Internal standard: Tetramethylsilane (TMS)

[0122] [1] Synthesis of organopolysiloxane

[0123] [Example 1-1]

[0124] In a 1 L three-necked flask equipped with a stirring device, a condenser, a dropping funnel, and a thermometer, 472 g (2.0 moles) of 3-glycidoxypropyltrimethoxysilane and 60 g of isopropanol were charged. 108 g (6.0 moles based on the amount of water) of 0.2% hydrochloric acid was dropped therein (the temperature was controlled in the range of 20 to 40 °C during dropping). After the dropping was completed, the mixture was stirred at 70 °C for 1 hour, and then, under reduced pressure distillation was carried out at 70 °C to remove the alcohol and the remaining water produced by the hydrolysis reaction, thereby obtaining a colorless transparent liquid organopolysiloxane (Ep1).

[0125] The kinematic viscosity of the obtained organopolysiloxane at 25 °C was 395 mm 2 / s, the amount of functional groups of epoxy groups contained is 198 g / mol, and the weight-average molecular weight is 608. Using 1 the results of H-NMR and GPC determination and analysis: The organopolysiloxane (Ep1) has a structure represented by the following formula (2). 1 The H-NMR spectrum is shown in Figure 1 .

[0126] [Chemical formula 6]

[0127]

[0128] [Example 1-2]

[0129] In Example 1-1, except that isopropanol was changed to 74 g of isobutanol, the same operations as in Example 1-1 were carried out to obtain a colorless transparent liquid organopolysiloxane (Ep2).

[0130] The kinematic viscosity of the obtained organopolysiloxane at 25 °C is 432 mm 2 / s, the amount of functional groups of epoxy groups contained is 202 g / mol, and the weight-average molecular weight is 668. Using 1 the results of H-NMR and GPC determination and analysis: The organopolysiloxane (Ep2) has a structure represented by the following formula (3).

[0131] [Chemical formula 7]

[0132]

[0133] [Comparative Example 1-1]

[0134] 472 g (2.0 mol) of 3-glycidoxypropyltrimethoxysilane was charged into a 1 L three-necked flask equipped with a stirring device, a condenser, a dropping funnel, and a thermometer. 108 g (6.0 mol in terms of water amount) of 0.2% hydrochloric acid was dropped therein (the temperature was controlled within the range of 20 to 40 °C during the dropping). After the dropping was completed, it was stirred at 70 °C for 1 hour, and then, under reduced pressure distillation was carried out at 70 °C to remove the alcohol and the remaining water produced by the hydrolysis reaction, thereby obtaining a colorless transparent liquid organopolysiloxane (Ep3).

[0135] The kinematic viscosity of the obtained organopolysiloxane at 25 °C is 726 mm 2 / s, the amount of functional groups of epoxy groups contained is 189 g / mol, and the weight-average molecular weight is 830. Using 1 the results of H-NMR and GPC determination and analysis: The organopolysiloxane (Ep3) has a structure represented by the following formula (4).

[0136] [Chemical formula 8]

[0137]

[0138] [Comparative Example 1-2]

[0139] In a 1 L three-necked flask equipped with a stirring device, a condenser, a dropping funnel, and a thermometer, 141.6 g (0.6 mol) of 3-glycidoxypropyltrimethoxysilane and 168 g (1.4 mol) of dimethyldimethoxysilane were charged. 82.8 g (4.6 mol in terms of water amount) of 0.2% hydrochloric acid was dropped therein (temperature was controlled within the range of 20 to 40 °C during the dropping). After the dropping was completed, stirring was carried out at 70 °C for 1 hour, and then, under reduced pressure distillation was carried out at 70 °C to remove the alcohol generated by the hydrolysis reaction and the remaining water, thereby obtaining a colorless transparent liquid organic polysiloxane (Ep4).

[0140] The kinematic viscosity of the obtained organic polysiloxane at 25 °C was 181 mm 2 / s, the functional group amount of the epoxy group contained was 288 g / mol, and the weight average molecular weight was 930. The results of analysis by 1 1H-NMR and GPC determination: The organic polysiloxane (Ep4) had a structure represented by the following formula (5).

[0141] Furthermore, when the organic polysiloxane (Ep4) was mixed with ion-exchanged water, it was incompatible, turbid, and had poor water solubility.

[0142] [Chemical Formula 9]

[0143]

[0144] [2] Storage Stability Evaluation

[0145] [Examples 2-1, 2-2, Comparative Example 2-1]

[0146] For the organic polysiloxanes (Ep1 to Ep3) synthesized in Examples 1-1, 1-2 and Comparative Example 1-1, the kinematic viscosity and water solubility after just being manufactured, one month, two months, and three months of storage at room temperature and 5 °C were evaluated. The results are shown in Table 1.

[0147] Furthermore, regarding water solubility, when each organic polysiloxane was mixed with ion-exchanged water at 25 °C to a concentration of 10%, the case where it was uniformly dissolved was evaluated as "〇", and the case where turbidity occurred was evaluated as "×".

[0148] [Table 1]

[0149]

[0150] As shown in Table 1, in Comparative Example 2-1 using the organopolysiloxane Ep3 without a bulky alkoxysilyl group, the increase in viscosity over time and the decrease in water solubility due to the condensation reaction were significant. Such a material can only be processed immediately after production and is thus considered to have a quality unsuitable for practical use.

[0151] Regarding the organopolysiloxanes Ep1 and Ep2 obtained in Examples 1-1 and 1-2, although the same time-dependent change behavior was observed at 25°C, the degree was small, and almost no change was shown during storage at 5°C.

[0152] [3] Production and Evaluation of Primer Compositions

[0153] [Examples 3-1, 3-2, Comparative Examples 3-1 to 3-5]

[0154] The compositions prepared by diluting the primer components shown in Table 2 below with ion-exchanged water to a solid content of 30% were applied to polished steel plates and dried for 30 minutes in an environment of 25°C and 50% RH.

[0155] Then, 100 parts of the aqueous coating resin BURNOCK WD-551 (manufactured by DIC Corporation) and 30 parts of the isocyanate-based curing agent BURNOCK DNW-5500 (manufactured by DIC Corporation) were mixed, and the aqueous polyurethane coating diluted with water was applied using a No. 14 bar coater. After standing for 3 days in an environment of 25°C and 50% RH, it was cured under the conditions of 80°C for 4 hours.

[0156] Regarding the coatings obtained above, the following evaluations were performed. The results are shown in Table 2.

[0157] (1) Coating Appearance

[0158] The coating film was visually observed to determine the presence or absence of abnormalities.

[0159] ○: No abnormality

[0160] △: Coloring

[0161] ×: Abnormalities such as foreign matter, unevenness, and turbidity

[0162] (2) Initial Adhesion

[0163] According to JIS K5600, using a razor blade, six vertical and six horizontal cuts were made at 2 mm intervals in the coating film to create 25 checkerboards. After a transparent tape Cellotape (registered trademark, manufactured by NICHIBAN Co., Ltd.) was well adhered, when it was sharply peeled off in the front direction at 90°, the number of grids (X) where the coating film did not peel off and remained was expressed as X / 25.

[0164] (3) Boiling Sealing Property

[0165] For the sealing property after immersing the evaluation sample in boiling water for 10 hours, it is evaluated in the same manner as the above-mentioned initial sealing property.

[0166] (4) Pencil Hardness

[0167] It is measured by the method of pencil scratching test described in JIS K5600-5-4 with a load of 750 g applied.

[0168] [Table 2]

[0169]

[0170] KBM403: 3-Glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0171] KBE903: 3-Aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0172] MP200: Hydrolysis condensate of 3-glycidoxypropyltrimethoxysilane (manufactured by Momentive Performance Materials, CoatOSil MP200 Silane)

[0173] Eg-Pr: Composition containing [3-(2,3-dihydroxyprop-1-yloxy)propyl]silanol oligomer described in Example 4 of Japanese Patent Application Laid-Open No. 2017-114852

[0174] As shown in Table 2, in Examples 3-1 and 3-2 where the organopolysiloxanes Ep1 and Ep2 obtained in Examples 1-1 and 1-2 were used as primer components, the film appearance, sealing property, and hardness of the polyurethane coating were shown to be excellent. This result shows that the organopolysiloxane of the present invention can be used as a sealing contributing component for water-based coatings with low environmental burden, not limited to primers, and shows the possibility of application as an internal additive for coatings to improve sealing.

[0175] On the other hand, in Comparative Examples 3-1 and 3-3 where 3-glycidoxypropyltrimethoxysilane and its hydrolysis condensate were used as primer components, the result was insufficient sealing property.

[0176] Comparative Example 3-2 was a primer component with an amino group having high reactivity with the polyurethane coating. Although the result showed good improvement in sealing property, it was found that the reactivity was too high, and the coatability of the polyurethane coating deteriorated significantly, resulting in damage to the film appearance.

[0177] In Comparative Example 3-4, due to the insufficient reactivity of the ethylene glycol structural group with the polyurethane coating, the sealing property was poor.

Claims

1. An organopolysiloxane represented by the following formula (1) [Chemical formula 1] In the formula, R 1 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 2 is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a glycidyloxy group, R 3 is a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, and at least a part of R 3 is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms, and a, b, c, and d are numbers satisfying a ≥ 0.5, b ≥ 0, c ≥ 0, d ≥ 0, and a + b + c + d = 1, and x and y are numbers satisfying x ≥ 1 and 0 < y ≤ 0.

5.

2. The organopolysiloxane according to claim 1 wherein R 3 is a monovalent saturated hydrocarbon group having 3 or 4 carbon atoms.

3. The organopolysiloxane according to claim 1 or 2 wherein b, c, d, and y are numbers satisfying b = 0, c = 0, d = 0, and 0.01 ≤ y ≤ 0.1 4. A method for producing an organopolysiloxane, which is a method for producing the organopolysiloxane according to any one of claims 1 to 3. One or more silane monomers including a silane compound containing 3-glycidoxypropyl represented by the following formula (i), an optionally used silane compound represented by the following formula (ii), a silane compound represented by the following formula (iii), and a silane compound represented by the following formula (iv) are added with 0.8 to 1.1 times the molar amount of water relative to 1 mole of the Si(OR) group (R is a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms) of the silane monomer in the presence of an alcohol represented by the following formula (v), and a (co)hydrolysis condensation reaction of the silane monomer is carried out under acidic conditions [Chemical formula 2] In the formula, R 1 , R 2 and R are the same as above, and R 0 is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms.

5. An adhesion promoter, which contains the organopolysiloxane according to any one of claims 1 to 3 6. An aqueous coating composition, which contains the organopolysiloxane according to any one of claims 1 to 3 7. A primer composition, which contains the organopolysiloxane according to any one of claims 1 to 3

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