Surface treatment method, and method for manufacturing a substrate using the surface treatment method.

Abstract

To provide a surface treatment method that combines higher hydrophilicity and water slip property, and a method for manufacturing a base material with the surface treatment method.SOLUTION: A surface treatment method comprising: contacting a hydrophilic slip water treatment agent containing an organic silicon compound (A) in which at least one hydrophilic chain-containing group, and at least one hydrolyzable group are bonded to at least one silicon atom, and a metal alkoxide (B) on a surface of a base material to form a hydrophilic slip water membrane; and alkali treating or acid treating the hydrophilic water slip water membrane, and a method of manufacturing a base material with the surface treatment method.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a surface treatment method for making a hydrophilic and hydrophobic coating formed by contacting a substrate with a hydrophilic and hydrophobic treatment agent more hydrophilic and hydrophobic, and to a method for manufacturing a substrate using the surface treatment method. [Background technology]

[0002] There is a need for technology that can impart both hydrophilicity and hydrophobicity to the surface of a substrate. For example, in a heat exchanger using aluminum, in order to suppress noise generation caused by condensation on the fin surface, scattering of water droplets, and contamination due to mold growth, it is preferable to apply a surface treatment that has high wettability (high hydrophilicity) and allows attached water droplets to slide off and be removed quickly while they are still minute (high hydrophobicity).

[0003] Patent Document 1 describes a surface treatment method that includes the step of contacting the surface of a substrate to be given hydrophilic and hydrophobic properties with a hydrophilic and hydrophobic treatment agent containing an organosilicon compound (A) in which at least one silicon atom is bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group, and a metal alkoxide (B) in a predetermined molar ratio to form a hydrophilic and hydrophobic film (Claim 1, 9). Specifically, it is described that the substrate was immersed in the hydrophilic and hydrophobic treatment agent, and after being removed, the substrate was heated or dried at room temperature to produce a hydrophilic and hydrophobic film (Paragraph

[0090] ).

[0004] Non-patent document 1 lists a target value of 30° or less for the water contact angle between both ends of a water droplet onto which 2 μL of pure water has been dropped, as an indicator of the initial hydrophilicity and hydrophilicity persistence of a pre-coated fin material for air conditioners. It also lists a target value of 13° or less for the angle (falling angle) when a fin material with 10 μL of water droplets has been dropped onto it and tilted at a speed of 1° / sec, causing the forward end to move 0.2 mm. However, it only states that a bar coater was used as the coating method. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-117636 [Non-patent literature]

[0006] [Non-Patent Document 1] UACJ Technical Reports. Vol.5(2018),pp.80-83 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Patent Document 1 describes that, regarding the wettability and water-repellent properties of a hydrophilic-hydrophobic coating, the contact angle θs of a water droplet with respect to the coating, which is an indicator of hydrophilicity, was 40° or less, and the falling angle θt, which indicates water droplet removal properties, was 30° or less for a 10 μL water droplet with a tilting speed of 1° / second. However, judging from the target values ​​in Non-Patent Document 1, the hydrophilicity and hydrophobicity of the coating were still insufficient.

[0008] In view of the above circumstances, the present invention aims to provide a surface treatment method that achieves both higher hydrophilicity and hydrophobicity compared to a surface treatment method that includes a step of forming a hydrophilic hydrophobic film described in Patent Document 1, and a method for manufacturing a substrate using the surface treatment method. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the present inventors have discovered that a hydrophilic and hydrophobic coating (hereinafter referred to as "high hydrophilic and hydrophobic coating") can be obtained by a surface treatment method in which a hydrophilic and hydrophobic coating formed by contacting a hydrophilic and hydrophobic treatment agent containing an organosilicon compound and a metal alkoxide with the surface of a substrate is treated with alkali or acid, thereby achieving a coating that is capable of achieving both higher hydrophilicity and hydrophobicity than conventional coatings (hereinafter referred to as "high hydrophilic and hydrophobic coating"). This has led to the completion of the present invention.

[0010] In other words, the means for solving the above problem include the following embodiments. [1] On the surface of the substrate, A step of forming a hydrophilic and hydrophobic film by contacting an organosilicon compound (A), in which at least one silicon atom is bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group, with a hydrophilic and hydrophobic treatment agent containing a metal alkoxide (B), A step of improving the hydrophilicity and water-repellent properties of the hydrophilic and water-repellent coating by treating it with an alkali or acid, A surface treatment method including [2] The alkali treatment is the surface treatment method of [1] using sodium hydroxide. [3] The acid treatment is the surface treatment method of [1] using sulfuric acid. [4] The organosilicon compound (A) is represented by the following general formula (1), and the surface treatment method is any one of [1] to [3] above.

[0011] [ka] (In the formula, R 1 R is an alkyl group having 1 to 5 carbon atoms. 2 , R 3 is an alkylene group having 1 to 5 carbon atoms, q is an integer greater than or equal to 4, and each R 2 They may be the same or different from each other, R 4 These are each an alkyl group having 1 to 5 carbon atoms. [5] The surface treatment method of [4], wherein the hydrophilic water-repellent treatment agent further comprises a modified silicone oil (C) represented by the following general formula (2) and having a molecular weight of 10,000 or less.

[0012] [ka] (In the formula, R 5 represents a hydrophilic chain-containing group, R 6 Each of these independently represents an alkyl group with 1 to 5 carbon atoms, where m and n are integers, and m / n is between 1 and 6. [6] In formula (2) above, R 5 R7 -O(CH2CH2O) p -CH3(R 7 is a group represented by an alkylene group having 1 to 5 carbon atoms and p is an integer of 5 to 10), the surface treatment method of [5]. [7] The organosilicon compound (A) is represented by the following formula (3), the surface treatment method of [1].

[0013] [Chemical formula] (In the formula, each R 8 is independently an alkyl group having 1 to 5 carbon atoms, each R 9 is independently an alkylene group having 1 to 5 carbon atoms, R 10 is an alkylene group having 1 to 5 carbon atoms, q is an integer of 4 or more, and each R 10 may be the same or different from each other.) [8] A hydrophilic and hydrophobic film containing a hydrolyzed and condensed product of an organosilicon compound (A) in which at least one hydrophilic chain-containing group and at least one hydrolyzable group are bonded to at least one silicon atom, formed on the surface of the substrate, and a metal alkoxide (B), and the step of improving hydrophilicity and hydrophobicity by subjecting it to alkali treatment or acid treatment, is included in the surface treatment method. The alkali treatment uses sodium hydroxide, the surface treatment method of [8].

[10] The acid treatment uses sulfuric acid, the surface treatment method of [8].

[11] The organosilicon compound (A) is represented by the following general formula (1), the surface treatment method according to any one of [8] to

[10] .

[12] The organosilicon compound (A) is represented by the following general formula (1), the surface treatment method according to any one of [8] to

[10] .

[11] The organosilicon compound (A) is represented by the following general formula (1), the surface treatment method according to any one of [8] to

[10] .

[0014] [Chemical formula] (In the formula, R 1 is an alkyl group having 1 to 5 carbon atoms, R 2 , R 3is an alkylene group having 1 to 5 carbon atoms, q is an integer greater than or equal to 4, and each R 2 They may be the same or different from each other, R 4 These are each an alkyl group having 1 to 5 carbon atoms.

[12] Formed on the surface of the substrate, An organosilicon compound (A) represented by the following general formula (1), wherein at least one silicon atom is bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group, Metal alkoxide (B) and, A hydrophilic and hydrophobic coating containing a modified silicone oil (C) with a molecular weight of 10,000 or less, represented by the following general formula (2), and a hydrolyzed and condensed polymer thereof, A process of improving hydrophilicity and hydrophobicity by alkaline treatment or acid treatment. A surface treatment method including

[0015] [ka] (In the formula, R 1 R is an alkyl group having 1 to 5 carbon atoms. 2 , R 3 is an alkylene group having 1 to 5 carbon atoms, q is an integer greater than or equal to 4, and each R 2 They may be the same or different from each other, R 4 These are each an alkyl group having 1 to 5 carbon atoms.

[0016] [ka] (In the formula, R 5 represents a hydrophilic chain-containing group, R 6 Each of these independently represents an alkyl group with 1 to 5 carbon atoms, where m and n are integers, and m / n is between 1 and 6.

[13] In formula (2) above, R 5 However, R 7 -O(CH2CH2O) p -CH3(R 7 The surface treatment method of

[12] , wherein the group is an alkylene group having 1 to 5 carbon atoms, and p is an integer from 5 to 10.

[14] The organosilicon compound (A) is represented by the following formula (3), and the surface treatment method is one of the above [8] to

[10] .

[0017] [ka] (In the formula, each R 8 Each of these is an alkyl group having 1 to 5 carbon atoms, and each R 9 Each of these is an alkylene group with 1 to 5 carbon atoms, and R 10 is an alkylene group having 1 to 5 carbon atoms, q is an integer greater than or equal to 4, and each R 10 They may be the same or different from each other.

[15] A method for producing a substrate having a highly hydrophilic and hydrophobic coating formed on its surface using any one of the surface treatment methods described in [1] to

[14] above.

[16] The method of

[15] wherein the substrate is at least one selected from metal, metal oxide, silicon, glass, or resin.

[17] The method of

[15] wherein the substrate is a fin material for a heat exchanger. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a surface treatment method for forming a highly hydrophilic and hydrophobic coating on a substrate that achieves both higher hydrophilicity and hydrophobicity compared to the prior art, and a method for manufacturing a substrate using the surface treatment method. [Brief explanation of the drawing]

[0019] [Figure 1] Diagram illustrating the static contact angle (θS), an index used to evaluate hydrophilicity. [Figure 2] An explanatory diagram of the sliding angle (θT), one of the indicators used to evaluate water repellency. [Figure 3] An explanatory diagram of the advancing contact angle (θA) in contact angle hysteresis (△θ), another indicator used to evaluate water repellency. [Figure 4] An explanatory diagram of the receding contact angle (θR) in contact angle hysteresis (△θ), another indicator used to evaluate water repellency. [Figure 5] This schematic diagram shows an example of a surface treatment method including an alkali treatment step according to this embodiment. [Figure 6] This schematic diagram shows an example of a surface treatment method including the acid treatment step according to this embodiment. [Figure 7] This figure shows the changes over time in the static contact angle (θS), advancing contact angle (θA), and receding contact angle (θR) of the highly hydrophilic and hydrophobic coating after undergoing the alkali treatment process according to this embodiment. [Figure 8] This figure shows the relationship between the presence or absence of the alkali treatment step and the sliding angle (θT) according to this embodiment. [Figure 9] This figure shows the changes over time in the static contact angle (θS), advancing contact angle (θA), and receding contact angle (θR) of a highly hydrophilic and hydrophobic coating after undergoing the acid treatment process according to this embodiment. [Modes for carrying out the invention]

[0020] The present invention provides a surface treatment method for forming a highly hydrophilic and hydrophobic coating on a substrate surface by contacting the substrate surface with a hydrophilic and hydrophobic treatment agent containing an organosilicon compound (A) and a metal alkoxide (B), forming a hydrophilic and hydrophobic coating, and then treating the hydrophilic and hydrophobic coating with alkali or acid to form a highly hydrophilic and hydrophobic coating on the substrate surface that achieves a higher level of both hydrophilicity and hydrophobicity than conventional methods. The present invention will now be described in more detail, including its best mode, in specific embodiments (hereinafter also referred to as "these embodiments"). However, the present invention is not limited to these embodiments, and various other embodiments are included as long as they fall within the scope of the technical idea described in the claims. When numerical ranges are indicated using "~", it means that the lower and upper limits of that range are also included.

[0021] First, let's explain the indicators of hydrophilicity and hydrophobicity. <Static contact angle θ S > The static hydrophilicity of a highly hydrophilic and superhydrophobic coating is indicated by the static contact angle θ of water with respect to the coating. S You can use it. As shown in Figure 1, the static contact angle θ S This is the angle between the liquid surface and the solid surface of a stationary droplet; the smaller this value, the higher the static hydrophilicity. Static contact angle θ of the highly hydrophilic and water-repellent coating according to this embodiment S The static contact angle θ is preferably 30° or less, more preferably 25° or less, and even more preferably 20° or less. S If the temperature is 30° or lower, it can be expected to be fully utilized in the fields of building stain resistance and heat exchangers.

[0022] <Sliding angle θ T > One indicator of the water-slip properties of a highly hydrophilic and water-slip coating is the sliding angle θ. T You can use it. As shown in Figure 2, the sliding angle θ T This value represents the angle of inclination of a solid surface required for a liquid droplet to gradually tilt and begin to slide down. The smaller this value, the better the water-repellent properties. The highly hydrophilic and water-repellent coating according to this embodiment has a water sliding angle θ relative to the coating. T However, for a volume of 10 μL of water droplets, the angle is preferably 15° or less, and more preferably 10° or less. T The lower limit is not particularly restrictive; the lower the better.

[0023] <Contact angle hysteresis (Δθ=θ) A -θ R )> Contact angle hysteresis (Δθ) can also be used as another indicator of the hydrophilicity of highly hydrophilic coatings. Contact angle hysteresis Δθ is the advancing contact angle θ due to the expansion and contraction of a droplet in contact with a solid surface. A and the receding contact angle θ R The difference (θ) A -θ R It can be calculated from ). As shown in Figure 3, the advancing contact angle θ A This is the contact angle when the three-phase contact line advances as the liquid volume is gradually increased after inserting a syringe needle into a droplet formed on a solid surface. Furthermore, as shown in Figure 4, the receding contact angle θ R This is the contact angle when the three-phase contact line retracts as the droplet is gradually drawn in. Smaller values ​​for the advancing and receding contact angles indicate higher dynamic hydrophilicity, while smaller values ​​for contact angle hysteresis indicate higher hydrophobicity. The contact angle hysteresis Δθ of the highly hydrophilic and hydrophobic coating according to this embodiment is preferably 10° or less, and more preferably 5° or less.

[0024] <Hydrophilic and water-repellent treatment agent> The organosilicon compound (A) and metal alkoxide (B) included as essential components in the hydrophilic water-repellent treatment agent according to this embodiment, the modified silicone oil [C] included as an optional component, and other components will be described in detail below.

[0025] [Organosilicon compounds (A)] In this embodiment, organosilicon compound (A) is a compound in which at least one silicon atom is bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group.

[0026] Since a silicon atom is a tetravalent element, it can be bonded to up to four groups. In this invention, at least one of the four groups is a hydrophilic chain-containing group, and at least one is a hydrolyzable group. Therefore, the remaining two groups bonded to the silicon atom are not particularly limited and may be a hydrophilic chain-containing group, a hydrolyzable group, or any other group. Furthermore, if there are multiple hydrophilic chain-containing groups or multiple hydrolyzable groups, the hydrophilic chain-containing groups and hydrolyzable groups may be the same or different from each other.

[0027] In this embodiment, the preferred organosilicon compound (A) is an organosilicon compound (A1) represented by the following formula (1), having one hydrophilic chain-containing group and three hydrolyzable groups per silicon atom.

[0028] [ka] (In the formula, R 1 R is an alkyl group having 1 to 5 carbon atoms. 2 , R 3 is an alkylene group having 1 to 5 carbon atoms, q is an integer greater than or equal to 4, and each R 2 They may be the same or different from each other, R 4 These are each an alkyl group having 1 to 5 carbon atoms.

[0029] Another preferred organosilicon compound (A) is the organosilicon compound (A2) represented by the following formula (3).

[0030] [ka] (In the formula, each R 8 Each of these is an alkyl group having 1 to 5 carbon atoms, and each R 9 Each of these is an alkylene group with 1 to 5 carbon atoms, and R 10 is an alkylene group having 1 to 5 carbon atoms, q is an integer greater than or equal to 4, and each R 10 They may be the same or different from each other.

[0031] In other words, organosilicon compound (A2) is a so-called hexafunctional compound in which a polyalkylene glycol structure, which is a hydrophilic chain-containing group, is bonded between the silicon atoms at both ends, and three alkoxy groups, which are hydrolyzable groups, are bonded to each of the silicon atoms at both ends. Based on the hypothesis that a larger number of terminal hydrolyzable groups increases the number of reaction sites, thereby improving adhesion to the substrate and bonding with the metal alkoxide (B), the inventors used compound (A2) represented by formula (3) above. They found that, compared to using the trifunctional organosilicon compound (A1) represented by formula (1), hydrophilicity was maintained while hydrophobicity was significantly improved.

[0032] (Hydrophilic chain-containing group) In the organosilicon compound (A1) shown in formula (1) above, the group represented by formula (4) below corresponds to the hydrophilic chain-containing group.

[0033] [ka] Furthermore, in the organosilicon compound (A2) represented by formula (3), the group represented by the following formula (5) corresponds to the hydrophilic chain-containing group.

[0034] [ka] In equation (4), [R 2 -O], or [R in formula (5) 10 The repeating structural unit of [-O] plays a role in exhibiting hydrophilicity. R in equation (4) 2 , or R in equation (5) 10 The alkylene group having 1 to 5 carbon atoms is particularly preferably an ethylene group. 2 or R 10 Because it is an ethylene group, it is possible to ensure water droplet removal while maintaining high hydrophilicity.

[0035] In the hydrophilic chain-containing group represented by formula (4) or formula (5) above, [R 2 -O] or [R 10 The number of repeating units q is usually an integer of 4 or more, and from the viewpoint of availability, it is preferably an integer between 4 and 30. When q is 4 or more, the chain length that exhibits hydrophilicity becomes longer, increasing the hydrophilicity of the organosilicon compound (A), and as a result, the hydrophilicity of the formed film becomes sufficient.

[0036] Furthermore, in the hydrophilic chain-containing group represented by formula (4) above, R 1 is an alkyl group having 1 to 5 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group. The presence of a methoxy group with a methyl group and oxygen bonded to the terminal, R 1 Compared to the case of H, hydrogen bonding with water can be suppressed.

[0037] In the hydrophilic chain-containing group represented by formula (4) or formula (5) above, R 3 or R 9 This is the part that bonds to the silicon atom, and it is an alkylene group with 1 to 5 carbon atoms. 3 or R 9 The alkylene group having 1 to 5 carbon atoms is usually linear, and being linear allows for better water droplet removal.

[0038] (hydrolyzable group) The hydrolyzable group in organosilicon compound (A) is not particularly limited as long as it is a group that yields a hydroxyl group (silanol group) upon hydrolysis. Furthermore, in organosilicon compound (A) of the present invention, it is sufficient that at least one hydrolyzable group is bonded to one silicon atom, but it is preferable that three hydrolyzable groups are bonded to one silicon atom. When two or three hydrolyzable groups are bonded to a silicon atom, the hydrolyzable groups may be the same or different from each other.

[0039] The hydrolyzable groups in organosilicon compound (A) are sites that react with metal alkoxide (B), as well as sites that react with the substrate to which the hydrophilic water-repellent treatment agent is applied. Therefore, the hydrolyzable groups in organosilicon compound (A) react with the interior of the formed film while also reacting with the substrate to which the film is formed, thereby increasing the adhesion strength of the formed film to the substrate.

[0040] In this embodiment, the hydrolyzable group of the organosilicon compound (A1) is the OR in formula (1). 4 Therefore, the hydrolyzable group of the organosilicon compound (A2) is the OR in formula (3). 8These groups are preferably alkoxy groups having 1 to 5 carbon atoms, more preferably methoxy, ethoxy, propoxy, or butoxy groups, and particularly preferably methoxy or ethoxy groups. Because the hydrolyzable group is a methoxy or ethoxy group, the alcohol produced after hydrolysis is of low molecular weight, allowing the hydrophilic water-repellent treatment agent in contact with the substrate to be dried and film-formed at a lower temperature.

[0041] The content of organosilicon compound (A) in the hydrophilic water-repellent treatment agent according to this embodiment is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass, relative to the total treatment agent.

[0042] [Metal alkoxide (B)] In this invention, the metal alkoxide (B) is a compound in which an alkoxy group is bonded to a metal atom. The metal alkoxide acts as a binder, improving adhesion / bonding not only to the substrate but also to the organosilicon compound (A) and PEG silicone oil (C). Furthermore, the metal alkoxide (B) forms spaces between the hydrophilic chain-containing groups, thereby improving the mobility of the hydrophilic chain-containing groups.

[0043] In this embodiment, the metal alkoxide (B) preferably has a structure represented by the following general formula (6).

[0044] [ka] (In the formula, M is a trivalent or tetravalent metal atom, R is an alkyl group having 1 to 5 carbon atoms, which may be the same or different from each other, and r is an integer of 3 or 4, depending on the valency of M.) Furthermore, the metal alkoxide (B) in this embodiment may be a hydrolysis condensate of the compound represented by formula (6) above. Here, a hydrolysis condensate means a compound in which all or some of the alkoxy groups contained in the metal alkoxide (B) are condensed by hydrolysis.

[0045] Examples of metal M constituting the metal alkoxide (B) include trivalent metals such as Al, Fe, and In, and tetravalent metals such as Hf, Si, Ti, Sn, and Zr. Among these, Si is preferred from the viewpoint of availability and storage stability.

[0046] Furthermore, when metal M is a trivalent metal, three alkoxy groups RO are bonded, meaning that r in formula (6) above is 3. When metal M is a tetravalent metal, four alkoxy groups R-O are bonded, meaning that r in formula (6) above is 4.

[0047] The alkoxy group RO preferably has 1 to 4 carbon atoms, and to allow the treatment agent in contact with the substrate to dry at a lower temperature and facilitate film formation, it is more preferable that it be a methoxy or ethoxy group with 1 or 2 carbon atoms.

[0048] Furthermore, if the hydrolyzable group of organosilicon compound (A) is an alkoxy group, the alkoxy group of organosilicon compound (A) and the alkoxy group of metal alkoxide (B) may be the same or different.

[0049] The content of metal alkoxide (B) in the hydrophilic water-repellent treatment agent according to this embodiment is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 1.0 to 10% by mass, relative to the total treatment agent.

[0050] The molar ratio (A / B) of the organosilicon compound (A) is preferably 0.01 to 0.5, and more preferably in the range of 0.03 to 0.3. In this embodiment, the metal alkoxide (B) forms a space between the linear hydrophilic chain-containing groups of the organosilicon compound (A), thereby improving the mobility of the hydrophilic chain-containing groups and enabling the formation of a film that balances hydrophilicity and water droplet removal properties, which are difficult to achieve simultaneously. If the molar ratio (A / B) of the organosilicon compound (A) to the metal alkoxide (B) is in the range of 0.01 to 0.5, an appropriate space can be formed between the linear hydrophilic chain-containing groups, and as a result, a balanced combination of hydrophilicity and water droplet removal properties can be achieved.

[0051] [Modified silicone oil (C)] The hydrophilic and water-repellent treatment agent according to this embodiment may contain, as an essential component, an organosilicon compound (A), represented by formula (1) (A1) and a metal alkoxide (B), in addition to a modified silicone oil (C) represented by the following general formula (2) with a molecular weight of 10,000 or less. When a hydrophilic and water-repellent film formed using a hydrophilic and water-repellent treatment agent to which a modified silicone with a molecular weight of 10,000 or less has been added is subjected to alkali treatment or acid treatment, the hydrophilicity and water-repellent properties can be improved compared to a conventional hydrophilic and water-repellent film without the addition of the modified silicone oil (C).

[0052] [ka] (In the formula, R 5 represents a hydrophilic chain-containing group, R 6 Each of these independently represents an alkyl group with 1 to 5 carbon atoms, where m and n are integers, and m / n is between 1 and 6.

[0053] In this embodiment, the R in formula (2) of the modified silicone oil (C) with a molecular weight of 10,000 or less 5 is a hydrophilic chain-containing group R 7 -O(CH2CH2O) p -CH3(R 7It is preferable that the group is an alkylene group having 1 to 5 carbon atoms, and p is an integer from 5 to 10. Hereinafter, this silicone oil will also be referred to as PEG-modified silicone oil. When the molecular weight of the PEG-modified silicone oil exceeds 10,000, the mobility of the hydrophilic chain-containing groups decreases, resulting in a decrease in dynamic hydrophilicity. Furthermore, even if the molecular weight is 10,000 or less, it is preferable to use a small amount of additive in order to maintain the mobility of the hydrophilic chain-containing groups.

[0054] Preferred PEG silicone oils with a molecular weight of 10,000 or less include, for example, Gelest, Inc.'s DBE-712 (molecular weight 600, PEG ratio 60-70%), DBE-814 (molecular weight 1,000, PEG ratio 80-85%), and DBE-224 (molecular weight 10,000, PEG ratio 25-30%). The amount added is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 1% by mass or less, based on the total mass of the organosilicon compound (A) and metal alkoxide (B) which are the solid components of the hydrophilic water-repellent treatment agent.

[0055] [Other ingredients] In this embodiment, the hydrophilic water-repellent treatment agent may optionally contain other components in addition to the organosilicon compound (A) and metal alkoxide (B) described above. Examples of other components include solvents, catalysts, and additives.

[0056] Examples of solvents include water, hydrophilic organic solvents such as alcohol-based solvents, ether-based solvents, ketone-based solvents, ester-based solvents, and amide-based solvents, and hydrophobic organic solvents such as aromatic hydrocarbon-based solvents and saturated hydrocarbon-based solvents. These may be used individually or in combination of two or more.

[0057] Preferably, the catalyst acts as a hydrolysis catalyst. Examples include acidic compounds such as hydrochloric acid, nitric acid, and acetic acid; basic compounds such as ammonia and amines; and organometallic compounds with a metal element as the central metal.

[0058] As additives, for example, antioxidants, rust inhibitors, ultraviolet absorbers, light stabilizers, fungicides, antibacterial agents, biofouling inhibitors, deodorizers, pigments, flame retardants, antistatic agents, etc., can be arbitrarily selected and blended within a range that does not hinder the effects of the present invention, as long as they exhibit the desired function.

[0059] In this embodiment, it is preferable that the total mass of the solid content in the hydrophilic water-repellent treatment agent be about 10%.

[0060] <Hydrophilic and slippery film formation process> The hydrophilic and hydrophobic coating process according to this embodiment involves contacting a hydrophilic and hydrophobic treatment agent containing an organosilicon compound (A) and a metal alkoxide (B) with the surface of a substrate that has been pretreated as needed, and performing hydrolysis and condensation polymerization reactions (sol-gel reactions) to form a film.

[0061] The method for bringing the hydrophilic water-repellent treatment agent into contact with the substrate is not particularly limited, and known methods can be applied. Examples include spin coating, dip coating, spray coating, roll coating, bar coating, and die coating.

[0062] The conditions such as temperature and time when contacting the hydrophilic water-repellent treatment agent are not particularly limited, and known conditions necessary for the progress of the sol-gel reaction can be applied.

[0063] Figure 5 shows an example of the hydrophilic and hydrophobic coating formation process and the subsequent alkaline treatment procedure according to this embodiment, based on Example 1 described later. In this example, a treatment agent is prepared by thoroughly stirring and mixing an organosilicon compound (A), a metal alkoxide (B), and other components such as a solvent and a hydrolysis catalyst. This agent is then coated onto the surface of a substrate to which hydrophilic and hydrophobic properties are to be desired, followed by a heat treatment to induce a hydrolysis-condensation polymerization reaction, and finally a water rinse to form a hydrophilic and hydrophobic film.

[0064] <Hydrophilic and slippery film> In the above-described process according to this embodiment, the hydrolyzable group of the organosilicon compound (A) reacts with the metal alkoxide (B) to form a hydrophilic and hydrophobic film containing a hydrolyzed and condensed polymer of the organosilicon compound (A) and the metal alkoxide (B). Furthermore, it reacts with the substrate on which the film is formed, thus enabling the formation of a hydrophilic and hydrophobic film with enhanced adhesion strength to the substrate. Furthermore, modified silicone oil (C) with a molecular weight of 10,000 or less does not contain reactive functional groups, but the hydroxyl groups (-OH) generated by hydrolysis contribute to the sol-gel reaction. Therefore, when using a hydrophilic and water-repellent treatment agent containing the modified silicone oil (C) with an organosilicon compound (A1) and a metal alkoxide (B), a hydrophilic and water-repellent film is formed in which the modified silicone oil (C) is contained in the hydrolyzed and condensed polymer.

[0065] The film thickness of the hydrophilic and hydrophobic coating according to this embodiment is not particularly limited, but is preferably 0.05 g / m². 2 The above applies, more preferably 0.1~2 g / m 2 The film thickness is 0.05 g / m². 2 By doing so, the hydrophilic and hydrophobic properties and corrosion resistance of the coating can be maintained even after alkaline or acidic treatment.

[0066] <Alkali treatment, acid treatment> The alkaline treatment or acid treatment according to this embodiment is a post-treatment step performed to impart superior hydrophilicity and hydrophobicity to the hydrophilic and hydrophobic coating.

[0067] [Alkaline treatment] In this embodiment, the alkaline treatment is preferably carried out by using an alkaline solution such as a sodium hydroxide solution and bringing the substrate surface on which a hydrophilic, hydrophobic film has been formed into contact with the alkaline solution for a certain period of time. Specifically, as shown in Figure 5, it is preferable to immerse a substrate on which a hydrophilic, hydrophobic coating has been formed in an alkaline solution, or to apply or spray an alkaline solution onto the surface of the substrate. When immersing a substrate in 1M sodium hydroxide, the longer the treatment time, the higher the hydrophilicity becomes, so it is preferable to treat for more than 1 minute. However, if the hydrophilicity becomes too high, the water droplets will draw a tail and θ T Δθ becomes unmeasurable. Therefore, a processing time of 6 minutes or less is preferable.

[0068] [Acid treatment] In this embodiment, the acid treatment is preferably carried out by using an acidic solution such as concentrated sulfuric acid and allowing the surface of the substrate on which the hydrophilic and hydrophobic film is formed to come into contact with the acidic solution for a certain period of time. Specifically, as shown in Figure 6, it is preferable to immerse a substrate on which a hydrophilic, hydrophobic coating has been formed in an acidic solution, or to apply or spray an acidic solution onto the surface of the substrate. When immersing the substrate in concentrated sulfuric acid, the treatment time is preferably 10 minutes or more to improve hydrophilicity. Furthermore, to maintain water-repellent properties, the treatment time is preferably 8 hours or less, and more preferably 2 hours or less.

[0069] <Base material> The substrate according to this embodiment is not particularly limited as long as it can generate a hydrophilic and water-repellent film containing the organosilicon compound (A), metal alkoxide (B), or the organosilicon compound (A1), metal alkoxide (B), and silicone oil (C) with a molecular weight of 10,000 or less by contact with the hydrophilic and water-repellent treatment agent, and is not damaged by subsequent alkali treatment or acid treatment. Examples include thermoplastic resins such as acrylic resin, polycarbonate resin, polyester resin, styrene resin, acrylic-styrene copolymer resin, cellulose resin, polyolefin resin, and polyvinyl alcohol, and thermosetting resins such as phenolic resin, urea resin, melamine resin, epoxy resin, unsaturated polyester, silicone resin, and urethane resin. Other examples include ceramics, glass, metals such as iron, silicon, copper, zinc, and aluminum, and alloys containing the aforementioned metals.

[0070] Furthermore, a degreasing process may be performed on the substrate before the hydrophilic-hydrophobic coating formation process, which involves degreasing and subsequent washing with water.

[0071] Alternatively, the resin substrate may be subjected to pretreatment such as an easy-adhesion treatment. Examples of easy-adhesion treatments include corona treatment, plasma treatment, ultraviolet treatment, silane compounds, silica (SiO2) film, or resin primer treatment. Furthermore, metal and alloy substrates may be coated with an SiO2 film. This improves the adhesion between the hydrophilic / hydrophobic film and the substrate, thereby improving the durability of the film against alkaline or acidic treatments and the corrosion resistance of the metal or alloy substrate.

[0072] For example, heat exchanger fins are an application where both hydrophilicity and water droplet removal properties are required, and a self-cleaning function is desired. The surface treatment method according to this embodiment can be suitably applied to aluminum, which is the base material for heat exchanger fins.

[0073] Furthermore, the shape of the base material is not particularly limited; for example, it may be a flat surface, a curved surface, or a three-dimensional structure composed of multiple surfaces. [Examples]

[0074] Next, examples of the present invention will be described, but the present invention is not limited to these examples.

[0075] <Alkaline treatment> (Example 1) As the organosilicon compound (A), 2.35 g of the compound PEG9-12-Si(Gelest,Inc.)(A1) shown in the following formula (7) was weighed, and as the metal alkoxide (B), 5.17 g of tetraethoxysilane TEOS (Wako Pure Chemical Industries, Ltd. (now Fujifilm Wako Pure Chemical Industries)) was weighed (molar ratio A / B = 0.15). These were then mixed with 44.5 mL of ethanol and 14.8 mL of 0.01 M hydrochloric acid and stirred overnight at room temperature to prepare the hydrophilic water-repellent treatment agent according to Example 1.

[0076] [Chemical formula]

[0077] This treatment agent was spin-coated on a 40 mm × 40 mm glass substrate and heated at 80°C for 3 hours to prepare a hydrophilic and water-repellent film. The hydrophilic and water-repellent film was rinsed with water. Then, an alkali treatment of immersing it in a 1M sodium hydroxide solution for 3 minutes was performed to form a highly hydrophilic and water-repellent film according to Example 1.

[0078] (Comparative Example 1) A hydrophilic and water-repellent film according to Comparative Example 1 was formed in the same manner as in Example 1, except that the alkali treatment was not performed. The hydrophilic and water-repellent film according to Comparative Example 1 corresponds to the conventional example described in Patent Document 1 of the prior art literature.

[0079] The static contact angle θ S , advancing contact angle θ A , receding contact angle θ R , contact angle hysteresis Δθ, and sliding angle θ T with respect to a 10 μL water droplet were measured. The results are shown in Table 1.

[0080] [Table 1]

[0081] From Table 1, it was found that by passing through the alkali treatment step, the static contact angle θ S , which is an index of hydrophilicity, and the contact angle hysteresis Δθ and sliding angle θ T , which are indices of water repellency, were significantly reduced, and the hydrophilicity and water repellency were improved.

[0082] (Examples 2, 3, Comparative Examples 2, 3) A hydrophilic lubricating treatment agent according to Example 1 was mixed with 0.16 g of PEG-modified silicone oil having a molecular weight of 600 (Gelest, Inc. DBE-712) (corresponding to 3% by mass based on the mass of components A and B remaining after film formation), and then, in the same manner as in Example 1, a hydrophilic lubricating treatment agent according to Example 2 was prepared. After forming a hydrophilic lubricating film in the same manner as in Example 1, an alkali treatment was performed to form a highly hydrophilic lubricating film according to Example 2. Also, a hydrophilic lubricating treatment agent according to Example 3 was prepared in the same manner as in Example 2, except that the PEG-modified silicone oil was changed to a product having a molecular weight of 10,000 (Gelest, Inc. DBE-224). Using this, a hydrophilic lubricating film was prepared, and an alkali treatment was performed to form a highly hydrophilic lubricating film according to Example 3. As comparative examples, hydrophilic lubricating films were prepared using the same hydrophilic lubricating treatment agents as in Examples 2 and 3, and the hydrophilic lubricating films without the subsequent alkali treatment were used as the films according to Comparative Example 2 and Comparative Example 3. The static contact angle θ S of the films according to Examples 2 and 3 and the film according to Comparative Example 2, the advancing contact angle θ A , the receding contact angle θ R , the contact angle hysteresis Δθ, and the sliding angle θ T with respect to a 10 μL water droplet are shown in Table 2. Note that "-" indicates unmeasured (the same applies hereinafter).

[0083]

Table 2

[0084] According to Table 2, it was found that when a hydrophilic lubricating film was prepared using a hydrophilic lubricating treatment agent obtained by adding a PEG-modified silicone oil (C) having a molecular weight of 10,000 or less to an organosilicon compound (A1) and a metal alkoxide (B), the hydrophilicity and lubricity were improved by adding an alkali treatment step.

[0085] [Examination of Immersion Time] (Examples 4, Comparative Example 4) A silane having polyethylene glycol as shown in formula (8) below (Gelest, Inc.: hereinafter referred to as "PEG25-30-Si2") (A2) was used as the organosilicon compound (A), and tetraethoxysilane TEOS was used as the metal alkoxide (B). The mixture was prepared by mixing A / B in a molar ratio of 0.075, adding ethanol and 0.01 M hydrochloric acid so that the solid content was approximately 12%, and stirring overnight at room temperature to prepare a hydrophilic water-repellent treatment agent.

[0086] [ka] A hydrophilic, water-repellent coating according to Comparative Example 4 was prepared on a glass substrate using the same hydrophilic, water-repellent treatment agent as in Example 1. This hydrophilic, hydrophobic coating was subjected to an alkaline treatment by immersion in a sodium hydroxide solution for the time shown in Table 3 below, to form the highly hydrophilic, hydrophobic coating according to Example 4. Static contact angle θ of the coatings in Example 4 and Comparative Example 4 S , advancing contact angle θ A , receding contact angle θ R , contact angle hysteresis Δθ, and sliding angle θ for a 10 μL water droplet T The measurement results, along with Comparative Example 1, which corresponds to a conventional example, are shown in Table 3 and Figure 7. Note that "-" indicates that measurement was not performed.

[0087] [Table 3]

[0088] Comparing Comparative Example 4 with Comparative Example 1 (conventional example) in Table 3, it was found that even without alkali treatment, using (A2) as the organosilicon compound resulted in improved hydrophilicity and hydrophobicity compared to using (A1). Furthermore, Table 3 and Figure 7 show that when organosilicon compound (A2) was used as organosilicon compound (A), the hydrophilicity significantly improved when an alkaline treatment step was added, and the water-slip properties also tended to improve further with alkaline treatment of 1 minute or more, and even with a short time of 30 seconds, it was found to be better than Comparative Example 1 (conventional example). However, if the processing time exceeds 6 minutes, the hydrophilicity improves too much, causing the water droplets to leave a trail, and the advance contact angle θ A , receding contact angle θ R , contact angle hysteresis Δθ, and sliding angle θ T Measurement was not possible. Therefore, it was not possible to evaluate the water-repellent properties.

[0089] [slip angle θ T [Consideration of water droplet size] In the highly hydrophilic and hydrophobic coating of Example 4, which underwent alkaline treatment for 4 minutes, and the coating of Comparative Example 4, which did not undergo alkaline treatment, the sliding angle θ was changed by changing the size of the water droplets placed on it from 1 to 50 μL. T The change was measured. The results are shown in Table 4 and Figure 8.

[0090] [Table 4]

[0091] Table 4 and Figure 8 show that alkaline treatment allows even small water droplets of 2 μL or 1 μL to slide down at a slight incline of 9° or 14°, confirming that not only is hydrophilicity improved, but hydrophobicity is also significantly enhanced.

[0092] <Acid treatment> (Example 5) In the same manner as in Example 4, a hydrophilic and hydrophobic coating prepared using an organosilicon compound (A2) was subjected to an acid treatment by immersion in concentrated sulfuric acid (95% H2SO4) for the time shown in Table 5 below, instead of the alkaline treatment, to produce a highly hydrophilic and hydrophobic coating according to Example 5. Static contact angle θ of the highly hydrophilic and hydrophobic coating according to Example 5 S , advancing contact angle θ A , receding contact angle θ R , contact angle hysteresis Δθ, and sliding angle θ for a 10 μL water droplet TThe results of the measurements are shown in Table 5, along with the results for Comparative Example 4, which used (A2) as the organosilicon compound and did not undergo acid or alkali treatment, and Comparative Example 1, which corresponds to a conventional example and used (A1) as the organosilicon compound and did not undergo acid or alkali treatment.

[0093] [Table 5]

[0094] Table 5 shows that adding an acid treatment as a post-processing step to a hydrophilic-hydrophobic coating takes longer than alkaline treatment, but it is possible to improve the hydrophilicity without significantly altering the hydrophobicity with a treatment of 10 minutes or more. However, it was found that if the treatment time exceeds 2 hours, there is little effect on improving hydrophilicity, while the water-slip properties tend to decrease, so acid treatment for 10 minutes to 2 hours is preferable. [Industrial applicability]

[0095] The surface treatment method according to this embodiment improves hydrophilicity and maintains or improves hydrophobicity by applying a post-treatment with alkali or acid to a conventional hydrophilic-hydrophobic coating. Therefore, it can be suitably used in applications where both hydrophilicity and hydrophobicity are required, and where a self-cleaning function is particularly desired, such as components of heat exchangers used in heat pump systems and transportation equipment that use air as a heat source, and especially in the manufacture of heat exchanger fin materials.

[0096] Furthermore, it can be widely applied to various components such as refrigeration equipment, power transmission equipment, communication equipment, and road infrastructure, as well as to window glass of automobiles, vehicles, and buildings, where both hydrophilicity and water droplet removal properties are required in environments that come into contact with water, and where a self-cleaning function is desired.

Claims

1. On the surface of the substrate, A step of forming a hydrophilic and hydrophobic film by contacting an organosilicon compound (A), in which at least one silicon atom is bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group, with a hydrophilic and hydrophobic treatment agent containing a metal alkoxide (B), A step of improving the hydrophilicity and water-repellent properties of the hydrophilic and water-repellent coating by treating it with an alkali or acid, A surface treatment method including

2. The surface treatment method according to claim 1, wherein the alkali treatment is performed using sodium hydroxide.

3. The surface treatment method according to claim 1, wherein the acid treatment is performed using sulfuric acid.

4. The surface treatment method according to claim 1, wherein the organosilicon compound (A) is an organosilicon compound (A1) represented by the following general formula (1). 【Chemistry 1】 (In the formula, R １ R is an alkyl group having 1 to 5 carbon atoms. ２ , R ３ is an alkylene group having 1 to 5 carbon atoms, q is an integer of 4 or more, and each R ２ They may be the same or different from each other, R ４ These are each an alkyl group having 1 to 5 carbon atoms.

5. The surface treatment method according to claim 4, wherein the hydrophilic water-repellent treatment agent further comprises a modified silicone oil (C) represented by the following general formula (2) and having a molecular weight of 10,000 or less. 【Chemistry 2】 (In the formula, R ５ represents a hydrophilic chain-containing group, R ６ Each of these independently represents an alkyl group having 1 to 5 carbon atoms, where m and n are integers, and m / n is between 1 and 6.

6. In the formula (2), R ５ is a group represented by R ７ -O(CH ２ CH ２ O) ｐ -CH ３ (R ７ is an alkylene group having 1 to 5 carbon atoms, and p is an integer of 5 to 10), and the surface treatment method according to claim 5.

7. The surface treatment method according to claim 1, wherein the organosilicon compound (A) is an organosilicon compound (A2) represented by the following formula (3). 【Transformation 3】 (In the formula, each R ８ Each of these is an alkyl group having 1 to 5 carbon atoms, and each R ９ Each of these is an alkylene group having 1 to 5 carbon atoms, and R １０ is an alkylene group having 1 to 5 carbon atoms, q is an integer of 4 or more, and each R １０ They may be the same or different from each other.

8. Formed on the surface of the substrate, An organosilicon compound (A) having at least one silicon atom bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group, A hydrophilic and hydrophobic coating containing a metal alkoxide (B) and its hydrolyzed and condensed polymer is provided. A process of improving hydrophilicity and hydrophobicity by alkaline treatment or acid treatment. A surface treatment method including

9. The surface treatment method according to claim 8, wherein the alkali treatment is performed using sodium hydroxide.

10. The surface treatment method according to claim 8, wherein the acid treatment is performed using sulfuric acid.

11. The surface treatment method according to claim 8, wherein the organosilicon compound (A) is an organosilicon compound (A1) represented by the following general formula (1). 【Chemistry 4】 (In the formula, R １ R is an alkyl group having 1 to 5 carbon atoms. ２ , R ３ is an alkylene group having 1 to 5 carbon atoms, q is an integer of 4 or more, and each R ２ They may be the same or different from each other, R ４ These are each an alkyl group having 1 to 5 carbon atoms.

12. Formed on the surface of the substrate, An organosilicon compound (A1) represented by the following general formula (1), wherein at least one silicon atom is bonded to at least one hydrophilic chain-containing group and at least one hydrolyzable group, Metal alkoxide (B) and A hydrophilic and hydrophobic coating containing a modified silicone oil (C) with a molecular weight of 10,000 or less, represented by the following general formula (2), and a hydrolyzed and condensed polymer thereof, A process of improving hydrophilicity and hydrophobicity by alkaline treatment or acid treatment. A surface treatment method including 【Transformation 5】 (In the formula, R １ R is an alkyl group having 1 to 5 carbon atoms. ２ , R ３ is an alkylene group having 1 to 5 carbon atoms, q is an integer of 4 or more, and each R ２ They may be the same or different from each other, R ４ These are each an alkyl group having 1 to 5 carbon atoms. 【Transformation 6】 (In the formula, R ５ represents a hydrophilic chain-containing group, R ６ Each of these independently represents an alkyl group having 1 to 5 carbon atoms, where m and n are integers, and m / n is between 1 and 6.

13. In the above formula (2), R ５ However, R ７ -O(CH ２ CH ２ O) ｐ -CH ３ (R ７ The surface treatment method according to claim 12, wherein the group is an alkylene group having 1 to 5 carbon atoms, and p is an integer from 5 to 10.

14. The surface treatment method according to claim 8, wherein the organosilicon compound (A) is an organosilicon compound (A2) represented by the following formula (3). 【Transformation 7】 (In the formula, each R ８ Each of these is an alkyl group having 1 to 5 carbon atoms, and each R ９ Each of these is an alkylene group having 1 to 5 carbon atoms, and R １０ is an alkylene group having 1 to 5 carbon atoms, q is an integer of 4 or more, and each R １０ They may be the same or different from each other.

15. A method for producing a substrate on which a highly hydrophilic and hydrophobic film is formed on its surface using the surface treatment method described in any one of claims 1 to 14.

16. The method according to claim 15, wherein the substrate is at least one selected from metal, metal oxide, silicon, glass, or resin.

17. The method according to claim 15, wherein the substrate is a fin material for a heat exchanger.

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