JP2016210831A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition capable of contributing to the reduction of VOC while being used in both application of water repellency and hydrophilicity, and capable of reducing the variation of the surface properties of the water repellency and hydrophilicity in a water-repellant or hydrophilic coating film obtained by a simple method.SOLUTION: Provided is, e.g., a coating composition containing: silica particles; alcoxysilane; an organic solvent; water; and fluorocarbon being liquid at 20°C, in which the fluorocarbon being at least either of hydrofluoroether or fluoroalcohol, in which the alcoxysilane is included in the weight ratio of the alcoxysilane/the fluorocarbon=0.05/1 to 30/1 to the fluorocarbon.SELECTED DRAWING: None

Description

  The present invention relates to a coating composition for uniformly modifying the surface of a substrate made of an inorganic material or an organic material.

  Conventionally, for example, by using a composition containing a metal alkoxide such as alkoxysilane, the surface of a substrate made of an inorganic material such as glass or earthenware and an organic material such as a resin or paint is repelled by a sol-gel method. Surface modification means such as imparting aqueous or hydrophilic properties are known.

  For example, Patent Document 1 discloses a treatment composition comprising a hydrophobized silica having a predetermined particle size, an alkoxysilane having an alkyl group, and a solvent, and the treatment composition is used. It is disclosed that when the porous tile back is modified, the contact angle exhibits water repellency of 120 ° or more.

  And in patent document 2, the inorganic coating composition which consists of a fine particle silica, an alkoxysilane, a solvent, and water is disclosed, and it apply | coated to the glass base material by spray coating using the inorganic coating composition. When the treatment is performed, it is disclosed that the contact angle exhibits hydrophilicity of 0 to 5 °.

  Further, in Patent Document 3, a film is formed on a glass plate using a treatment liquid comprising an alkoxysilane having an alkyl group and tetraalkoxysilane, and further, a plasma treatment is performed in a fluorinated gas atmosphere to form an alkyl group. A water-repellent substrate obtained through a fluorination step is disclosed, and the water droplet contact angle on the water-repellent substrate is about 117 ° or 147 °, and their standard deviation is 2.0-4. 3 is disclosed.

JP 2010-1221021 A Japanese Patent No. 3367953 JP 2010-248000 A

  However, in the composition of Cited Document 1, only alcohols or the like are used as a solvent, which does not sufficiently satisfy the recent demand for reduction of volatile organic compounds (VOC), and becomes a predetermined contact angle or more. Although it has been disclosed to exhibit water repellency, the accuracy of how much variation in water repellency has been unknown.

  Moreover, although it is disclosed in the composition of the cited document 2 that alcohol and water are used as a solvent and exhibit predetermined hydrophilicity, it can be provided with water repellency by changing the type of alkoxysilane. It was unclear, and the degree of variation in its hydrophilicity was also unclear.

  Further, the composition of Reference 3 has a variation within a predetermined range calculated from the contact angle of water droplets as a water-repellent composition, but the variation is large, and plasma treatment is performed in a fluorinated gas atmosphere. Therefore, various restrictions are imposed on actual use with respect to substrates of various sizes and places.

  Therefore, in the present invention, the water repellency in a water-repellent or hydrophilic coating film obtained by a simple method can be used for both water-repellent and hydrophilic applications and can contribute to the reduction of VOC. Alternatively, it is an object to provide a coating composition that can reduce variations in hydrophilic surface characteristics.

  The inventors of the present invention have made extensive studies on surface modifiers, can form water-repellent coatings as well as hydrophilic even if they contain water, and can be repelled by containing a predetermined fluorocarbon. It has been found that variations in surface characteristics in an aqueous or hydrophilic coating film can be reduced, and the present invention has been achieved based on these findings.

  [1] That is, the present invention is a coating composition comprising silica particles, alkoxysilane, an organic solvent, water, and a fluorocarbon which is liquid at 20 ° C.

  [2] The coating composition according to [1], wherein the fluorocarbon is at least one of a hydrofluoroether or a fluoroalcohol.

  [3] The above [1] or the above, wherein the alkoxysilane is contained in a weight ratio of the alkoxysilane / the fluorocarbon = 0.05 / 1 to 30/1 with respect to the fluorocarbon. [2] The coating composition according to [2].

[4] The water-repellent coating composition according to any one of [1] to [3], wherein the alkoxysilane is a compound represented by the following formula 1.
(Formula 1)
Xn-Si- (OY) 4-n
(Wherein X is an alkyl group having 1 to 18 carbon atoms, Y is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 3)

[5] The hydrophilic coating composition according to any one of [1] to [3], wherein the alkoxysilane is tetraalkoxysilane.

  According to the present invention, water repellency in a water-repellent or hydrophilic coating film obtained by a simple method can be used for both water-repellent and hydrophilic applications while contributing to the reduction of VOC. Alternatively, variation in hydrophilic surface characteristics can be reduced.

  Hereinafter, embodiments relating to the coating composition of the present invention will be described in detail. In addition, the description which shows the range in description contains an upper limit and a minimum.

  The coating composition of the present invention contains silica particles, an alkoxysilane, an organic solvent, water, and a fluorocarbon that is liquid at 20 ° C., and is an indicator of the performance of the treated surface after coating film preparation. When the contact angle with water is measured, a very homogeneous treatment with a standard deviation of the contact angle of 1 or less becomes possible.

  As silica particles contained in the present invention, methanol, isopropanol, dimethylacetamide, ethylene glycol, ethylene glycol mono-n-propyl ether, propylene glycol monomethyl ether, ethyl acetate, propylene glycol monomethyl ether acetate, methyl ethyl ketone, methyl isobutyl ketone, Silica sol dispersed in an organic solvent such as toluene and silica particles dispersed in acidic or alkaline water are preferred. One or two or more of these can be used in combination.

  And the average primary particle diameter of a silica particle is 2-100 nm which is a particle diameter calculated as a conversion value from the specific surface area measurement value (according to JIS Z8830) by a BET adsorption method, and it is 3-80 nm. More preferred. As the commercially available silica particles, Snow Chemicals (registered trademark) series colloidal silica manufactured by Nissan Chemical Co., Ltd. can be used.

  Moreover, it is preferable that the content rate of the silica particle in the coating composition of this invention is 0.01 to 5.0 weight%, and it is preferable that it is 0.03 to 3.0 weight%. When the content ratio of the silica particles is within this range, it is possible to impart appropriate hardness to the treated surface of the substrate while preventing aggregation of the silica particles.

  The alkoxysilane contained in the present invention is a member that imparts water repellency or hydrophilicity to the composition. For example, as the alkoxysilane, monofunctional trimethylmethoxysilane, triethylmethoxysilane, trimethylethoxysilane, triethylethoxysilane, etc., bifunctional dimethyldimethoxysilane, diethyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, dimethyldiethoxy Silane, diethyldiethoxysilane, etc., trifunctional methyltrimethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltri Methoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, n-tetradecyltrimeth Sisilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, n-propyltriethoxysilane, isopropyltriethoxysilane, n-butyltriethoxysilane, isobutyltriethoxysilane N-hexyltriethoxysilane, n-octyltriethoxysilane, n-decyltriethoxysilane, n-dodecyltriethoxysilane, n-tetradecyltriethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltriethoxy Silane and the like, tetrafunctional tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraisobutoxysilane and the like are preferable. One or two or more of these can be used in combination.

  Moreover, it is preferable that the content rate of the alkoxysilane in the coating composition of this invention is 0.1 to 5.0 weight%, and it is preferable that it is 0.2 to 3.0 weight%. When the content ratio of the alkoxysilane is within this range, the treated surface of the substrate can be made water repellent or hydrophilic.

  The organic solvent contained in the present invention is a solvent for uniformly dispersing silica particles and alkoxysilane. Examples of the organic solvent include lower alcohols having 1 to 4 carbon atoms such as methanol, ethanol, isopropanol, and normal propanol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, and ethylene glycol monoisopropyl ether. , Diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monobutyl ether acetate, ethylene glycol monohexyl ether, di Tylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol mono Propyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol methyl Ethyl ether, diethylene glycol dibutyl ether, glycol ethers such as dipropylene glycol dimethyl ether are preferred. In addition, nonpolar organic solvents such as aliphatic hydrocarbons and aromatic hydrocarbons can be used as necessary. Moreover, 1 type or 2 types or more of these can be used in combination.

The fluorocarbon that is liquid at 20 ° C. contained in the present invention is a member for keeping the surface of the coating film of the composition homogeneous. Examples of the fluorocarbon include perfluoropropyl methyl ether (C ₃ F ₇ OCH ₃ , boiling point: 34 ° C., freezing point: −123 ° C.), perfluorobutyl methyl ether (C ₄ F ₉ OCH ₃ , boiling point: 61 ° C., freezing point: −135 ° C.), perfluoropropyl ethyl ether (C ₄ F ₉ OC ₂ H ₅ , boiling point: 76 ° C., freezing point: −138 ° C.), 3-perfluorohexyl methyl ether (C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ , Boiling point: 98 ° C., pour point: −38 ° C.), 2,2,2-trifluoroethanol (CF ₃ CH ₂ OH, boiling point: 78 ° C., freezing point: −45 ° C.), 1, 1,1,3,3,3-hexafluoro-2-propanol _((CF 3) 2 CHOH, boiling point: 58 ° C., solidifying point: -4 ° C. , 2,2,3,3 _{(HCF 2 CF 2 CH 2 OH} , boiling point: 109 ° C., solidification point: -15 ° C.) fluoro alcohols such as 2,2,2-trifluoro-acetophenone ((CF ₃ COPh, boiling point: 165 ° C., freezing point: −40 ° C.) and the like, and m-xylene hexafluoride (boiling point: 116 ° C., freezing point: −35 ° C.) are preferred. The liquid property is a state under 1 atm.

  Further, the content ratio of the fluorocarbon which is liquid at 20 ° C. in the coating composition of the present invention is preferably 0.01 to 10.0% by weight, and preferably 0.03 to 8.0% by weight. . When the content ratio of the fluorocarbon is within this range, the wettability to the substrate can be improved and the surface of the coating film made of the composition can be made uniform.

  Further, the alkoxysilane is preferably contained at a weight ratio of alkoxysilane / the fluorocarbon = 0.05 / 1 to 30/1 with respect to the fluorocarbon which is liquid at 20 ° C., and the alkoxysilane / the fluorocarbon = 0. More preferably, it is contained in a weight ratio of 1/1 to 20/1. When the weight ratio between the alkoxysilane and the fluorocarbon is within this range, the variation in the contact angle of a plurality of water droplets on the surface of the coating film of the composition is very small, that is, the standard deviation is 1 or less. So that it can be homogeneous.

  Water contained in the present invention is a solvent in the composition. As the water, any water such as purified water and industrial water can be used. Moreover, the trace component contained in water may also be contained in the range which does not affect the sclerosis | hardenability at the time of coating-film preparation.

  The proportion of water in the composition of the present invention is preferably 0.1 to 70% by weight, and preferably 0.5 to 50% by weight.

  The coating composition of the present invention can be prepared by mixing each component and then stirring at room temperature, but it can also be heated and stirred within the boiling point range of the organic solvent. Furthermore, a method of diluting a concentrated liquid composed of silica particles, alkoxysilane, an organic solvent and a part of water with another organic solvent after stirring or heating with stirring is also possible. In that case, a reaction accelerator can be used. Examples of the reaction accelerator include inorganic acids such as hydrochloric acid and sulfuric acid, acids typified by organic acids such as acetic acid and citric acid, amines such as ammonia and organic amines, and organic metals including aluminum and titanium. Is preferred.

  And, the coating composition of the present invention comprises a surfactant such as a cationic surfactant, an anionic surfactant, an amphoteric surfactant and a nonionic surfactant, an ultraviolet absorber, and an antifouling agent, if necessary. , Viscosity adjusting agents, coloring agents, preservatives, pH adjusting agents and the like can be added.

  The coating composition of the present invention is preferably made of glass, resin, metal, ceramics or the like as the target substrate.

  The method for treating each substrate with the surface coating composition of the present invention is not particularly limited, and may be treated by spin coating, dip coating, roll coating, flow coating, spray coating, etc. You may process by the hand coating etc. which used the jig | tool. Then, a cured coating film is obtained by sufficiently drying by natural drying or heat drying.

  Examples of the present invention will be specifically described below. In addition, this invention is not limited to a following example.

Example 1
Isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST) 0.5% by weight, methyltrimethoxysilane 0.5% by weight, ethanol 60% by weight, ethylene glycol monoisobutyl ether 14% by weight, water 20 A coating composition consisting of 5.0% by weight of 3-perfluorohexyl methyl ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] (manufactured by 3M Japan, trade name: Novec7300) was obtained.

(Example 2)
4. Isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST) 0.05% by weight, n-hexyltrimethoxysilane 0.25% by weight, isopropanol 64.4% by weight, dipropylene glycol monomethyl ether A coating composition comprising 30% by weight of 0% water and 0.3% by weight of fluoroalcohol (1,1,1,3,3,3-hexafluoro-2-propanol) was obtained.

Example 3
0.25% by weight of isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST), 0.5% by weight of n-decyltrimethoxysilane, 82.3% by weight of isopropanol, 15% by weight of water, 3- A coating composition comprising 2.0% by weight of perfluorohexyl methyl ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] (manufactured by 3M Japan, trade name: Novec 7300) was obtained.

Example 4
Isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST) 0.025% by weight, n-decyltrimethoxysilane 1.0% by weight, isopropanol 97.0% by weight, ethylene glycol monohexyl ether A coating composition comprising 4% by weight, 0.5% by weight of water and 0.05% by weight of fluoroalcohol (1,1,1,3,3,3-hexafluoro-2-propanol) was obtained.

(Example 5)
Isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST) 1.0% by weight, dimethyldimethoxysilane 0.5% by weight, isopropanol 87.5% by weight, water 10% by weight, 3-perfluorohexylmethyl A coating composition comprising 1.0% by weight of ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] (manufactured by 3M Japan, trade name: Novec 7300) was obtained.

(Example 6)
0.5% by weight of isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST), 0.5% by weight of trimethylmethoxysilane, 93.9% by weight of isopropanol, 5% by weight of water, 3-perfluorohexylmethyl A coating composition comprising 0.1% by weight of ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] (manufactured by 3M Japan, trade name: Novec 7300) was obtained.

(Example 7)
Isopropanol-dispersed silica sol (manufactured by Nissan Chemical Industries, trade name: IPA-ST) 0.5% by weight, tetraethoxysilane 0.5% by weight, ethanol 45.0% by weight, propylene glycol monopropyl ether 3.5% by weight , 50% by weight of water, 3-perfluorohexyl methyl ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] (manufactured by 3M Japan, trade name: Novec7300) 0.5% by weight is obtained. It was.

(Comparative Example 1)
In Example 1, ethanol was added instead of 3-perfluorohexyl methyl ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] to obtain a coating composition.

(Comparative Example 2)
In Example 2, isopropanol was added instead of 1,1,1,3,3,3, -hexafluoro-2-propanol to obtain a coating composition.

(Comparative Example 3)
In Example 3, isopropanol was added instead of 3-perfluorohexyl methyl ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] to obtain a coating composition.

(Comparative Example 4)
In Example 4, isopropanol was added instead of 1,1,1,3,3,3, -hexafluoro-2-propanol to obtain a coating composition.

(Comparative Example 5)
In Example 5, isopropanol was added instead of 3-perfluorohexyl methyl ether [C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ ] to obtain a coating composition.

(Comparative Example 6)
In Example 6, isopropanol was added instead of 3-perfluorohexyl methyl ether to obtain a coating composition.

(Comparative Example 7)
In Example 7, ethanol was added instead of 3-perfluorohexyl methyl ether to obtain a coating composition.

  The obtained compositions are listed and shown in Table 1.

  For each surface modifier, each surface modifier soaked in a sponge is treated on a polished and cleaned soda glass plate (25 mm × 75 mm) surface, and after natural drying for 1 day, DropMaster of Kyowa Interface Science Co., Ltd. is used. The contact angle of water on the treated glass surface was measured at 5 points by the θ / 2 method, and the average value and standard deviation were confirmed. The values are shown in Table 2.

  As shown in Table 2, in the coating compositions of Examples 1 to 7, it can be used for both water-repellent and hydrophilic applications even if it contains water, and further in a water-repellent or hydrophilic coating film. It has been found that variations in surface properties of water repellency or hydrophilicity can be reduced. In particular, by blending a fluorocarbon that is liquid at 20 ° C., the composition can be blended uniformly in the composition, and a coating film can be easily produced because treatment by a gas phase reaction or the like is not required.

Claims (5)

Silica particles;
Alkoxysilane,
An organic solvent,
water and,
A coating composition comprising a fluorocarbon which is liquid at 20 ° C. The coating composition according to claim 1, wherein the fluorocarbon is at least one of a hydrofluoroether and a fluoroalcohol. The coating according to claim 1 or 2, wherein the alkoxysilane is contained in a weight ratio of the alkoxysilane / the fluorocarbon = 0.05 / 1 to 30/1 with respect to the fluorocarbon. Composition. The water-repellent coating composition according to any one of claims 1 to 3, wherein the alkoxysilane is a compound represented by the following formula 1.
(Formula 1)
Xn-Si- (OY) 4-n
(Wherein X is an alkyl group having 1 to 18 carbon atoms, Y is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 3) The hydrophilic coating composition according to any one of claims 1 to 3, wherein the alkoxysilane is tetraalkoxysilane.