Organopolysiloxane, adhesion imparting 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 methyl group or an ethyl 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 y < = 0.5. )

Description

Technical Field

[0001] The present invention relates to an organopolysiloxane, an adhesion promoter, an aqueous coating composition, and a primer composition. More specifically, it relates to an organopolysiloxane containing siloxane units having 3-glycidoxypropyl and diorganosiloxane units as constituent units and having silanol groups, an adhesion promoter composed of the organopolysiloxane, an aqueous coating composition containing the organopolysiloxane, and a primer composition. Background Art

[0002] Compounds having two or more different reactive functional groups in one molecule are known as coupling agents for bonding different types of materials. Among them, silane coupling agents 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 are known as primers for improving the adhesion of coatings and are also known as adhesion promoters added to coating compositions.

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

[0004] Compared with silane coupling agents, the advantages of using oligomers and / or polymers obtained by hydrolytic condensation thereof are, first of all, that since the molecular weight is high, the volatility is low, and it is possible to eliminate concerns about a reduction in the active ingredient during processes such as drying.

[0005] In addition, it can be cited that the amount of volatile organic compounds (VOCs) generated is small. From the viewpoint of reducing the environmental burden such as the water-based and solvent-free conversion of current solvent-based coatings, compared with silane coupling agents that generate alcohols by hydrolysis, the amount of alcohol generated per unit mass of the active ingredient in oligomers that have been partially hydrolyzed in advance is reduced, and it can be said that they are materials suitable for such requirements.

[0006] Aiming at further reduction of VOCs, an aqueous solution of a hydrolytic 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 hydrolytic condensate having functional groups 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 hydrolytic 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 organic functional groups 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 diorganosilanyloxy units respectively 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 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 methyl group or an ethyl 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 y≤0.5.

[0027] 2. The organopolysiloxane according to 1, wherein a, b, c, and d are numbers satisfying 0.5≤a≤0.9, b = 0, 0.1≤c≤0.5, and d = 0.

[0028] 3. An adhesion imparting agent comprising the organopolysiloxane according to 1 or 2.

[0029] 4. An aqueous coating composition comprising the organopolysiloxane according to 1 or 2.

[0030] 5. A primer composition comprising the organopolysiloxane according to 1 or 2.

[0031] Effects of the Invention

[0032] The organopolysiloxane of the present invention has a highly reactive epoxy group, and is excellent in the modification of an organic resin and the effect of improving the adhesion to a resin substrate, and has excellent stability, thus achieving a longer service life. In addition, the organopolysiloxane of the present invention has a silanol group, so it has excellent reactivity with an inorganic substrate. In addition, it exhibits high water solubility and can be used as an additive in an aqueous coating composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the 1 1H-NMR spectrum of the organopolysiloxane Ep1 obtained in Example 1-1. DETAILED DESCRIPTION

[0034] Hereinafter, the present invention will be specifically described.

[0035] (1) Organopolysiloxane

[0036] The organopolysiloxane of the present invention is represented by the following general formula (1).

[0037] [Chemical Formula 2]

[0038]

[0039] In the above formula, R 1is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and 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; 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.

[0040] 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 by 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.

[0041] R 3 is methyl or ethyl.

[0042] a, b, c, and d represent the molar ratios of the respective siloxane units and are numbers satisfying a + b + c + d = 1.

[0043] a is a number of 0.5 or more, preferably a number of 0.5 to 0.9. 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 highly viscous, gum-like or solid-like, with poor processability and reduced water solubility.

[0044] b is a number of 0 or more, and preferably 0 from the aspect of the amount of epoxy groups contained in the organopolysiloxane of the present invention.

[0045] c is a number greater than 0, preferably a number of 0.1 to 0.5. When c is 0, the above organopolysiloxane has a structure composed only of trisiloxane units and tetrasiloxane units, and the reactivity of the silanol groups contained therein is high. Therefore, the storage stability is insufficient, and problems that are not suitable for practical use occur.

[0046] d is a number of 0 or more, and preferably 0 from the aspect of the reactivity of the silanol groups.

[0047] x and y each represent the number of moles of hydroxyl groups and alkoxy groups bonded to 1 mole of Si atoms.

[0048] 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 and reactivity with inorganic substrates of the organopolysiloxane are poor.

[0049] y is a number of 0.5 or less, and from the viewpoint of reducing the alcohol produced by hydrolysis, a number of 0.4 or less is preferred.

[0050] As the organopolysiloxane of the present invention, an organopolysiloxane represented by the following formula (1a) is preferred.

[0051] [Chemical formula 3]

[0052]

[0053] In formula (1a), R 2 and R 3 are the same as above, a1 and c1 are numbers satisfying 0.5 ≤ a1 ≤ 0.9, 0.1 ≤ c1 ≤ 0.5, and a1 + c1 = 1, and x1 and y1 are numbers satisfying x1 ≥ 1 and y1 ≤ 0.5.

[0054] 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).

[0055] 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 Canon-Fenske viscometer.

[0056] 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 present in excess, it can react with epoxy groups. Therefore, when storing the organopolysiloxane of the present invention for a long time, it is desirable to contain as little water as possible.

[0057] (2) Method for producing organopolysiloxane

[0058] 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 more alkoxysilanes including 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane or a mixture thereof represented by the following formula (i), diorganodimethoxysilane, diorganodiethoxysilane or a mixture thereof represented by the following formula (iii), optionally an organotrimethoxysilane, organotriethoxysilane or a mixture thereof represented by the following formula (ii), and tetramethoxysilane, tetraethoxysilane or a mixture thereof represented by the following formula (iv) under acidic conditions.

[0059] [Chemical formula 4]

[0060]

[0061] (wherein, R 1 ~R 3 is the same as above.)

[0062] As specific examples of the diorganodimethoxysilane and diorganodiethoxysilane represented by the above formula (iii), dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentylmethyldiethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methyloctyldimethoxysilane, methyloctyldiethoxysilane, etc. can be mentioned.

[0063] As specific examples of the organotrimethoxysilane and organotriethoxysilane represented by the above formula (ii), methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane and other trialkoxysilanes can be mentioned.

[0064] In addition, the hydrolysis condensates of the above silane compounds can be used. These can be used alone or two or more of them can be used in combination.

[0065] It is preferable to adjust the usage amounts of these silane monomers according to the molar ratios (the values of a to d in formula (1)) of the respective siloxane units constituting the target organopolysiloxane.

[0066] From the viewpoints of suppressing the reaction with the epoxy group and reducing the residual alkoxysilyl group, the amount of water used in the hydrolysis of the alkoxysilane monomer is preferably 0.8 to 1.1 times the molar amount, more preferably 1 to 1.1 times the molar amount, relative to 1 mole of the alkoxysilyl group.

[0067] As the acid component adjusted to an acidic condition during the hydrolysis reaction, as long as it is a Bronsted acid that circulates in the market, there is no particular limitation. 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 organopolysiloxane obtained by the excessive dehydration condensation reaction between silanols and the decrease in the amount of silanol groups resulting in a decrease in water solubility, the usage amount of the acid is preferably 0.0001 to 0.01 mole relative to 1 mole of the silane monomer.

[0068] In the hydrolysis reaction, within a range that does not hinder the reaction, an organic solvent can be used as needed. As the organic solvent to be used, an organic solvent compatible with water as the reaction raw material is preferred, and alcohols, esters, ketones, ethers, etc. are preferred. In addition, considering the distillation conditions when removing the generated alcohol, it is preferred that the organic solvent has a low boiling point, and a solvent having a boiling point of 150°C or lower under atmospheric pressure is preferred.

[0069] Specific examples of alcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, neopentanol, hexanol, cyclohexanol, etc.

[0070] Specific examples of esters include ethyl acetate, butyl acetate, etc.

[0071] Specific examples of ketones include acetone, methyl ethyl ketone, cyclohexanone, etc.

[0072] Specific examples of ethers include tetrahydrofuran, tetrahydropyran, dioxane, etc.

[0073] The temperature of the hydrolysis reaction is preferably 55 to 70°C, and the reaction time is preferably 1 to 5 hours.

[0074] In addition, after the hydrolysis reaction of the silane monomer, the following process is preferably carried out: under reduced pressure, in the temperature range of 30 to 80°C, water, the alcohol generated by the hydrolysis of the alkoxysilyl group, and the above-mentioned organic solvent are distilled off.

[0075] 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.

[0076] (3) Aqueous coating composition

[0077] 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.

[0078] The aqueous coating composition of the present invention preferably contains water as a solvent, and in particular, is preferably an aqueous solution containing only water as a solvent. In addition, the compounding amount of the above-mentioned organopolysiloxane in the composition is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

[0079] As specific examples of the aqueous coating composition, compositions containing an aqueous resin such as an aqueous epoxy resin composition and an aqueous polyurethane resin composition can be cited. As one of the components of these aqueous resin compositions, the organopolysiloxane of the present invention can be used.

[0080] As specific examples of the aqueous resin, in addition to the aqueous epoxy resin and the aqueous polyurethane resin, an aqueous polyester resin, an aqueous acrylic resin, etc. can be cited.

[0081] In addition, the aqueous coating composition of the present invention can contain any additives such as organic solvents, antioxidants, ultraviolet absorbers, light stabilizers, thickeners, dispersants, and adhesion promoters within the range that does not hinder the effects of the present invention.

[0082] There is no particular limitation on the method for producing the aqueous coating composition of the present invention. For example, a method of mixing the above-mentioned organopolysiloxane, solvent, optionally used aqueous resin, and other additives according to a conventional method can be cited.

[0083] By directly applying the obtained aqueous coating composition onto a specified substrate or via other layers such as a primer layer 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.

[0084] As the substrate, there is no particular limitation, and examples include plastic molded articles, wood-based products, ceramics, glass, metals, and composites thereof.

[0085] As the coating method of the aqueous coating composition, there is no particular limitation, and it can be appropriately selected from conventionally 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.

[0086] (4) Primer composition

[0087] The organopolysiloxane of the present invention can be suitably used as a coupling component or an aqueous reactive adhesive in an aqueous primer composition (coating).

[0088] The primer 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] In addition, the primer 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 compounding amount of the above-mentioned organopolysiloxane in the composition is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

[0090] Furthermore, the primer composition of the present invention may contain optional additives within the 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.

[0091] There are no particular limitations on the method for producing 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.

[0092] In addition, other layers can be formed on the surface of the primer layer. As the other layers, for example, a coating layer composed of a cured coating 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 coating 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.

[0093] Examples

[0094] 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.

[0095] (1) GPC measurement conditions

[0096] Apparatus: HLC-8320GPC manufactured by Tosoh Corporation

[0097] Elution solvent: Tetrahydrofuran (THF)

[0098] Flow rate: 0.6 mL / min

[0099] Detector: Differential refractive index detector (RI)

[0100] Column: TSK Guardcolumn SuperH-H

[0101] TSKgel SuperHM-N (6.0 mm I.D. × 15 cm × 1)

[0102] TSKgel SuperH2500 (6.0 mm I.D. × 15 cm × 1)

[0103] (All manufactured by Tosoh Corporation)

[0104] Column temperature: 40 °C

[0105] Sample injection volume: 50 μL (THF solution with a concentration of 2.0%)

[0106] Standard: Monodisperse polystyrene

[0107] (2) 1 H-NMR measurement conditions

[0108] Apparatus: AVANCE III 400 manufactured by BURKER

[0109] Solvent: CDCl 3

[0110] Internal standard: Tetramethylsilane (TMS)

[0111] [1] Synthesis of organopolysiloxane

[0112] [Example 1-1]

[0113] In a 1 L three-necked flask equipped with a stirring device, a condenser, a dropping funnel, and a thermometer, 425 g (1.8 moles) of 3-glycidoxypropyltrimethoxysilane and 24 g (0.2 moles) of dimethyldimethoxysilane were charged. 104.4 g (5.8 moles based on the amount of water) of 0.2% hydrochloric acid was dropped therein (the temperature was controlled at 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).

[0114] The kinematic viscosity of the obtained organopolysiloxane at 25 °C was 429 mm 2 / s, the functional group amount of the epoxy group contained was 202 g / mole, and the weight average molecular weight was 610. The results of the analysis by 1 H-NMR and GPC measurements showed that the organopolysiloxane (Ep1) had a structure represented by the following formula (2). The 1 H-NMR spectrum is shown in Figure 1 .

[0115] [Chemical formula 5]

[0116]

[0117] [Example 1-2]

[0118] In Example 1-1, except that it was changed to 236 g (1.0 mole) of 3-glycidoxypropyltrimethoxysilane, 120 g (1.0 mole) of dimethyldimethoxysilane, and 90 g (5.0 moles based on the amount of water) of 0.2% hydrochloric acid, the same operations as in Example 1-1 were carried out to obtain a colorless transparent liquid organic polysiloxane (Ep2).

[0119] The kinematic viscosity of the obtained organic polysiloxane at 25 °C was 218 mm 2 / s, the functional group amount of the contained epoxy groups was 258 g / mol, and the weight-average molecular weight was 700. The results of 1 1H-NMR and GPC measurement and analysis: The organic polysiloxane (Ep2) had a structure represented by the following formula (3).

[0120] [Chemical formula 6]

[0121]

[0122] [Example 1-3]

[0123] In a 1 L three-necked flask equipped with a stirring device, a condenser, a dropping funnel, and a thermometer, 425 g (1.8 moles) of 3-glycidoxypropyltrimethoxysilane and 44 g (0.2 mole) of 3-glycidoxypropylmethyldimethoxysilane were charged. 104.4 g (5.8 moles based on the amount of water) of 0.2% hydrochloric acid was dropped therein (the temperature was controlled at 20-40 °C during 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 generated by the hydrolysis reaction, thereby obtaining a colorless transparent liquid organic polysiloxane (Ep3).

[0124] The kinematic viscosity of the obtained organic polysiloxane at 25 °C was 361 mm 2 / s, the functional group amount of the contained epoxy groups was 200 g / mol, and the weight-average molecular weight was 510. The results of 1 1H-NMR and GPC measurement and analysis: The organic polysiloxane (Ep3) had a structure represented by the following formula (4).

[0125] [Chemical formula 7]

[0126]

[0127] [Comparative Example 1-1]

[0128] 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 was charged. 108 g (6.0 moles based on the amount of water) of 0.2% hydrochloric acid was dropped therein (the temperature was controlled at 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 organic polysiloxane (Ep4).

[0129] The kinematic viscosity of the obtained organic polysiloxane at 25 °C was 726 mm 2 / s, the functional group amount of the contained epoxy group was 189 g / mol, and the weight average molecular weight was 830. The results of the 1 1H-NMR and GPC measurement and analysis: The organic polysiloxane (Ep4) had a structure represented by the following formula (5).

[0130] [Chemical formula 8]

[0131]

[0132] [Comparative Example 1-2]

[0133] In Example 1-1, except that 141.6 g (0.6 moles) of 3-glycidoxypropyltrimethoxysilane, 168 g (1.4 moles) of dimethyldimethoxysilane, and 82.8 g (4.6 moles based on the amount of water) of 0.2% hydrochloric acid were used, the same operation as in Example 1-1 was carried out to obtain a colorless transparent liquid organic polysiloxane (Ep5).

[0134] The kinematic viscosity of the obtained organic polysiloxane at 25 °C was 181 mm 2 / s, the functional group amount of the contained epoxy group was 288 g / mol, and the weight average molecular weight was 930. The results of the 1 1H-NMR and GPC measurement and analysis: The organic polysiloxane (Ep5) had a structure represented by the following formula (6).

[0135] Furthermore, when the organic polysiloxane (Ep5) was mixed with ion-exchanged water, it was incompatible, turbid, and had poor water solubility.

[0136] [Chemical formula 9]

[0137]

[0138] [2] Storage stability evaluation

[0139] [Examples 2-1 to 2-3, Comparative Example 2-1]

[0140] For the organopolysiloxanes (Ep1 to Ep4) synthesized in Examples 1-1 to 1-3 and Comparative Example 1-1, the kinematic viscosity and water solubility were evaluated after just being manufactured, after one month, two months, and three months when stored at room temperature (25 °C) and 5 °C. The results are shown in Table 1.

[0141] Furthermore, regarding water solubility, when each organopolysiloxane was mixed with ion-exchanged water to a concentration of 10% at 25 °C, the case where it dissolved uniformly was evaluated as "〇", and the case where turbidity occurred was evaluated as "×".

[0142] [Table 1]

[0143]

[0144] As shown in Table 1, it can be seen that in Comparative Example 2-1 using the organopolysiloxane Ep4 composed only of trisiloxane units without disiloxane units, the activity of the silanol is high, and the increase in viscosity over time and the decrease in water solubility due to the progress of the condensation reaction are significant. Such a material can only be processed just after being manufactured, and it can be said that it is not suitable for practical use in terms of quality.

[0145] Regarding the organopolysiloxanes Ep1 to Ep3 obtained in Examples 1-1 to 1-3, although the same change behavior over time was found at 25 °C, the degree was small, and almost no change was shown during storage at 5 °C.

[0146] [3] Manufacture and evaluation of primer compositions

[0147] [Examples 3-1 to 3-3, Comparative Examples 3-1 to 3-5]

[0148] The composition prepared by diluting the primer components shown in Table 2 below with ion-exchanged water to a solid content of 30% was applied to a polished steel plate and dried for 30 minutes in an environment of 25 °C and 50% RH.

[0149] Then, 100 parts of the water-based 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 water-diluted water-based polyurethane coating was applied using a bar coater No. 14 and allowed to stand for 3 days in an environment of 25 °C and 50% RH, and then cured under the conditions of 80 °C × 4 hours.

[0150] Regarding the coating films obtained above, the following evaluations were carried out. The results are shown in Table 2.

[0151] (1) Coating film appearance

[0152] The coating film was visually observed to determine the presence or absence of abnormalities.

[0153] ○: No abnormality

[0154] ×: Abnormality such as foreign matter, unevenness, and turbidity

[0155] (2) Initial adhesion

[0156] According to JIS K5600, using a razor blade, make 6 vertical and 6 horizontal cuts at 2 mm intervals in the coating film to form 25 checkerboards. After attaching the transparent tape Cellotape (registered trademark, manufactured by NICHIBAN Co., Ltd.) well, when peeling sharply in the front direction at 90°, express the number of grids (X) where the coating film remains unpeeled as X / 25.

[0157] (3) Boiling adhesion

[0158] For the adhesion after immersing the evaluation sample in boiling water for 10 hours, evaluate it in the same way as the above-mentioned initial adhesion.

[0159] (4) Pencil hardness

[0160] Adopt the method of pencil scratch test described in JIS K5600-5-4 and measure with a load of 750 g.

[0161] [Table 2]

[0162]

[0163] KBM403: 3-Glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0164] KBE903: 3-Aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0165] MP200: Hydrolysis condensate of 3-glycidoxypropyltrimethoxysilane (manufactured by Momentive Performance Materials, CoatOSil MP200 silane)

[0166] Eg-Pr: Composition containing [3-(2,3-dihydroxyprop-1-yloxy)propyl]silanol oligomer described in Example 4 of Japanese Patent Laid-Open No. 2017-114852

[0167] As shown in Table 2, in Examples 3-1 to 3-3 where the organopolysiloxanes Ep1 to Ep3 obtained in Examples 1-1 to 1-3 were used as primer components, the coating film appearance, adhesion, and hardness of the polyurethane coating were excellent. This result shows that the organopolysiloxane of the present invention can be used as an adhesion contributing component of a water-based coating with a small environmental burden, not limited to the primer, and shows the possibility of application as an adhesion improver added to the coating.

[0168] 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 adhesion.

[0169] Comparative Example 3-2 was a primer component having an amino group with high reactivity with the polyurethane coating. Although the result showed a good improvement in adhesion, it was found that the reactivity was too high, and the coatability of the polyurethane coating deteriorated significantly, resulting in damage to the appearance of the coating film.

[0170] In Comparative Example 3-4, due to the insufficient reactivity of the ethylene glycol structural group with the polyurethane coating, the adhesion 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 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 methyl or ethyl, 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 y ≤ 0.

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2. The organopolysiloxane according to claim 1, wherein a, b, c, and d are numbers satisfying 0.5 ≤ a ≤ 0.9, b = 0, 0.1 ≤ c ≤ 0.5, and d = 0.

3. An adhesion promoter comprising the organopolysiloxane according to claim 1 or 2.

4. An aqueous coating composition comprising the organopolysiloxane according to claim 1 or 2.

5. A primer composition comprising the organopolysiloxane according to claim 1 or 2.

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