Water repellent composition

Abstract

The purpose of the present invention is to provide a water repellent composition capable of forming a water repellent film in a short time on surfaces of various bases, the water repellent film being high in both static water repellency and dynamic water repellency and being less apt to change the appearances of the bases. The water repellent composition comprises a polycarboxylic acid and a silicone and is liquid at ordinary temperature and ordinary pressure.

Description

Water repellent composition

[0001] The present invention relates to a water repellent composition.

[0002] Compositions containing silicone compounds are widely known as water repellent compositions for imparting water repellency to the surface of a substrate. For example, Patent Document 1 describes a water repellent composition containing water, a water-soluble solvent, an amino-modified silicone oil, and a monovalent fatty acid.

[0003] Furthermore, Patent Document 2 describes a water repellent composition containing an alkoxysilane compound, sulfuric acid, and a volatile solvent.

[0004] JP-A No. 11-279541 JP-A No. 10-121036

[0005] Here, the water repellency of a substrate can be classified into static water repellency and dynamic water repellency. Static water repellency is expressed by the contact angle between the substrate and water. Dynamic water repellency is expressed by the ability to remove water droplets from the substrate. Until now, water repellency has only been evaluated by static water repellency, even in applications where water droplet removal is an issue. However, since there is not necessarily a correlation between static water repellency and dynamic water repellency, it is preferable to evaluate dynamic water repellency in applications where water droplets need to be removed. Dynamic water repellency can be quantified by the inclination angle at which water droplets begin to move (sliding angle) or the difference in contact angle before and after the water droplets move (contact angle hysteresis), and the smaller the value, the higher the ability to remove water droplets.

[0006] The present inventors have investigated known water repellent compositions and found that, for example, when a water repellent treatment film is formed using the water repellent composition described in Patent Document 1, although the contact angle is high and static water repellency is excellent, dynamic water repellency is poor and water droplet removal is poor. Patent Document 2 proposes a method for improving dynamic water repellency, in which an alkoxysilane compound is reacted and fixed on the coating surface. However, because a monomer molecule having a hydrolyzable group is used as the main water repellent component, dehydration and condensation reactions occur between the monomers during liquid storage, which tends to impair storage stability. Patent Document 2 also suggests that when silicone is used instead of a monomer, the surface on which the water repellent treatment film is formed is prone to poor appearance, resulting in a change in the appearance of the substrate.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a water repellent composition that can form a water repellent film in a short time, which has good static water repellency and dynamic water repellency and is unlikely to change the appearance of a substrate.

[0008] The present invention provides water repellent compositions according to the following [1] to [7]. [1] A water repellent composition comprising a polycarboxylic acid and a silicone, and being liquid at room temperature and normal pressure. [2] The water repellent composition according to [1], further comprising a liquid medium, wherein the silicone comprises at least one of a liquid silicone that is liquid at room temperature and normal pressure, and a solid silicone that is soluble in the liquid medium and is solid at room temperature and normal pressure. [3] The water repellent composition according to [2], wherein the amount of the liquid medium is 60% by mass or more and 99.99% by mass or less, based on the total amount of the water repellent composition. [4] The water repellent composition according to [2] or [3], wherein the liquid medium comprises water. [5] The water repellent composition according to any of [2] to [4], wherein the liquid medium comprises an alcohol. [6] The water repellent composition according to any of [1] to [5], wherein the silicone comprises an amino group. [7] The water repellent composition according to any one of [1] to [6], wherein the polycarboxylic acid contains 2 to 5 carboxy groups in one molecule.

[0009] The present invention provides a water repellent composition that can form, in a short period of time, a water repellent film on the surface of various substrates that has high static and dynamic water repellency and is unlikely to alter the appearance of the substrate.

[0010] Fig. 1A is a schematic diagram of a mixture of silicone and monocarboxylic acid, Fig. 1B is a schematic diagram of a mixture of silicone and dicarboxylic acid, Fig. 2A is a schematic diagram of a crosslinked structure when a non-amino group-containing silicone is mixed with carboxylic acid, and Fig. 2B is a schematic diagram of a crosslinked structure when an amino-modified silicone is mixed with carboxylic acid.

[0011] In this specification, a numerical range indicated by "to" means a numerical range including the numerical values ​​written before and after "to." Furthermore, in this specification, "liquid" includes not only a liquid in which a solute and a solvent, or different solvents, are completely dissolved, but also a suspension or emulsion in which at least one component is dispersed.

[0012] The water repellent composition of the present invention contains at least a polycarboxylic acid and a silicone and is a liquid composition at room temperature and normal pressure. In this specification, room temperature and normal pressure refer to a state of 25°C and 101 kPa. For example, when the silicone is a liquid silicone described below, the water repellent composition may mainly contain only a polycarboxylic acid and a silicone. However, it preferably contains a liquid silicone and / or solid silicone described below, a polycarboxylic acid, and a liquid medium for dissolving or dispersing the silicone and the polycarboxylic acid. Hereinafter, an example containing a liquid medium will be described, but the water repellent composition of the present invention is not limited thereto. The water repellent composition of the present invention is a composition for forming a water-repellent film on the surface of various substrates. The water repellent composition is mainly used by immersing a substrate in the water repellent composition or by applying the water repellent composition to a substrate.

[0013] The water repellent composition of the present invention can form a water-repellent film with high static and dynamic water repellency in a short period of time. The reason for this is unclear, but is thought to be as follows. FIG. 1A shows a schematic diagram of a mixture of silicone and monocarboxylic acid, and FIG. 1B shows a schematic diagram of a mixture of silicone and dicarboxylic acid. When silicone and carboxylic acid are mixed, oxygen in the silicone and a carboxy group of the carboxylic acid form a hydrogen bond. When silicone and monocarboxylic acid are mixed, as shown in FIG. 1A, the higher-order structure of the silicone does not change significantly before and after the formation of the hydrogen bond. In contrast, when silicone and dicarboxylic acid are mixed, as shown in FIG. 1B, since the dicarboxylic acid has two carboxy groups, the two carboxy groups of the carboxylic acid and the silicone each form a hydrogen bond. As a result, a crosslinked structure is formed within the same silicone and / or between different silicones via the dicarboxylic acid, and a higher-order structure develops. This allows the silicone to adhere to the substrate while maintaining a moderate aggregation state, and to be easily superimposed and fixed to the substrate. In other words, the water repellent composition of the present invention makes it possible to fix a large amount of silicone-derived components to the surface of the substrate, which is thought to enhance static and dynamic water repellency. The same effect can be obtained when the polycarboxylic acid contains three or more carboxy groups in one molecule.

[0014] In a composition in which silicone and monovalent carboxylic acid are mixed, as described in Patent Document 1, the crosslinked structure is not formed, and therefore the silicone does not easily adhere to the substrate in an aggregated state, making it difficult to fix silicone-derived components to the surface of the substrate.

[0015] Furthermore, as described in Patent Document 2, a composition obtained by mixing an alkoxysilane compound and sulfuric acid has low storage stability. On the other hand, in a composition obtained by mixing silicone and sulfuric acid, silicone is difficult to dissolve or disperse in a liquid medium, resulting in a non-uniform composition. When such a non-uniform composition is brought into contact with a substrate, silicone-derived components tend to adhere non-uniformly to the substrate. When silicone-derived components adhere to a certain region, the remaining silicone-derived components also tend to adhere to that region, resulting in a large amount of silicone-derived components adhering locally. As a result, not only is the thickness of the water-repellent treatment film formed non-uniform, but the thickness tends to increase in the region where the water-repellent treatment film is formed. This is thought to change the appearance of the substrate.

[0016] In contrast, the water repellent composition of the present invention has good stability and tends to have a uniform composition. Therefore, according to the water repellent composition of the present invention, the silicone-derived component is easily adhered uniformly to the surface of the substrate, and the thickness thereof is also moderate. Therefore, when a water repellent treatment film is formed, the appearance of the substrate is unlikely to change. Furthermore, the storage stability of the water repellent composition is also very good.

[0017] Each component contained in the water repellent composition of the present invention will be described below. In addition to the specific silicone, polycarboxylic acid, and liquid medium, the water repellent composition may contain other components as long as the purpose and effects of the present invention are not impaired. Examples of other components include various additives.

[0018] (Silicone) The silicone preferably contains at least one or both of a liquid silicone that is liquid at room temperature and normal pressure, and a solid silicone that is soluble in a liquid medium described below and is solid at room temperature and normal pressure.In addition, in this specification, silicone refers to an oligomer or polymer that contains a polysiloxane skeleton.The water repellent composition may contain only one type of silicone, or may contain two or more types.

[0019] The silicone has hydrophobicity whether it is a liquid silicone or a solid silicone. In this specification, "having hydrophobicity" means that more than 5 g of silicone does not dissolve in 100 g of water at room temperature and normal pressure.

[0020] The viscosity of liquid silicone at 25°C is 10 mm ２ / s~20000mm ２ / s is preferred, and 50 mm ２ / s ~ 5000mm ２ / s is more preferable. When the viscosity of the liquid silicone is in this range, it is easily compatible with the liquid medium and other components described below, and the viscosity of the water repellent composition is more likely to fall within the desired range. In this specification, the viscosity of the liquid silicone is a value measured using a capillary viscometer in accordance with JIS Z 8803 (2011). On the other hand, the solid silicone may be any silicone that is soluble in the liquid medium described below. Note that the solubility of a solid silicone in a liquid medium means that 0.1 g or more of the solid silicone dissolves in 100 g of the liquid medium described below at room temperature and normal pressure.

[0021] Here, the type of silicone is not particularly limited as long as it can form a water-repellent film on the surface of the substrate. The structure of the silicone may be linear or branched, and may have a modified functional group attached. Examples of the silicone include silicone oil and silicone resin. Examples of silicone oil include polyorganodisiloxane (straight silicone oil) whose skeleton is mainly composed of siloxane bonds, and modified products thereof (modified silicone oil). On the other hand, examples of silicone resin include organopolysiloxane having a three-dimensional crosslinked structure and modified products thereof. More specifically, silicone resin has a skeleton consisting of R ３ SiO １／２ M unit, R ２ SiO ２／２ D units represented by RSiO ３／２ T units represented by the formula: and SiO ４／２(in either unit, R represents an organic group), it is a resin containing at least T units and / or Q units, or a modified product thereof. When the silicone is the silicone resin, it is preferable that the ratio (R / Si) of the number (number of moles) of R contained in the silicone resin skeleton to the number (number of moles) of Si constituting the silicone resin skeleton is 1.0 to 1.7.

[0022] Specific examples of silicones (silicone oils and silicone resins) without modified functional groups include silicones in which a methyl group, a phenyl group, or a hydrogen atom is bonded to a polysiloxane skeleton, such as dimethyl silicone, methyl hydrogen silicone, and methyl phenyl silicone. Specific examples of silicones (silicone oils and silicone resins) with modified functional groups include amino-modified silicones, epoxy-modified silicones, polyether-modified silicones, fluoroalkyl-modified silicones, long-chain alkyl-modified silicones, higher fatty acid ester-modified silicones, carbinol-modified silicones, diol-modified silicones, methacrylic-modified silicones, carboxy-modified silicones, mercapto-modified silicones, and polyether methoxy-modified silicones. These may be prepared compounds or commercially available products.

[0023] From the viewpoints of achieving both static and dynamic water repellency and the appearance of the substrate surface after treatment with the water repellent composition, amino-modified silicones having amino groups are particularly preferred. The use of amino-modified silicones tends to ensure that the substrate after treatment with the water repellent composition has a water contact angle of 95° or more and a water sliding angle of 90° or less, and the appearance after treatment is also likely to be good. The amino-modified silicone may have an amino group on a side chain of the polysiloxane skeleton or at a terminal thereof, but it is more preferable that the amino group be on a side chain. FIG. 2A shows a schematic diagram of crosslinking between an amino-group-free silicone and a dicarboxylic acid, and FIG. 2B shows a schematic diagram of crosslinking between an amino-modified silicone and a dicarboxylic acid. As shown in FIG. 2A, when a silicone without an amino group (amino-group-free silicone) is mixed with a dicarboxylic acid, the carboxy group of the dicarboxylic acid forms a hydrogen bond with oxygen in the silicone (shown by the dotted line in FIG. 2A). In contrast, when an amino-modified silicone having an amino group in the side chain is mixed with a divalent carboxylic acid, in addition to the hydrogen bond (not shown) between the oxygen in the silicone and the carboxyl group, the amino group in the silicone reacts with the carboxyl group and bonds. As a result, it is thought that the crosslinked structure is stronger when using an amino-modified silicone than when using a silicone that does not contain amino groups. Furthermore, the amino-modified silicone easily adheres to the substrate while maintaining a moderate state of aggregation, and the amino-modified silicone easily overlaps and fixes to the substrate in a short period of time.

[0024] The amine equivalent of the amino-modified silicone is preferably 100 g / mol to 16,000 g / mol, and more preferably 1,000 g / mol to 15,000 g / mol. The amine equivalent can be determined by dividing the average molecular weight of the amino-modified silicone by the number of nitrogen atoms contained in the amino-modified silicone. The number of nitrogen atoms can be determined by elemental analysis. When the amine equivalent is within the above range, the crosslinked structure is easily formed appropriately by reaction with the polycarboxylic acid, and the amino-modified silicone is easily superimposed on and fixed to the substrate in a short period of time.

[0025] The concentration of silicone in the water repellent composition is preferably 0.01% by mass to 30% by mass, more preferably 0.1% by mass to 20% by mass, and even more preferably 0.3% by mass to 15% by mass. When the concentration of silicone in the water repellent composition is within this range, the silicone-derived component can be efficiently fixed to the surface of the substrate.

[0026] (Polycarboxylic Acid) The polycarboxylic acid may be any compound having two or more carboxy groups in one molecule, and may be a liquid compound at room temperature and normal pressure, or may be a solid compound at room temperature and normal pressure that is soluble or dispersible in the liquid medium described below. The number of carboxy groups in the polycarboxylic acid is not particularly limited, but is preferably 2 to 5, and more preferably a dicarboxylic acid having 2 carboxy groups. The water repellent composition may contain only one type of polycarboxylic acid, or may contain two or more types. Note that a solid polycarboxylic acid being soluble in the liquid medium described below means that 0.1 g or more of the polycarboxylic acid dissolves in 100 g of the liquid medium described below at room temperature and normal pressure.

[0027] The hydrocarbon group of the polycarboxylic acid may be linear or branched. Furthermore, the hydrocarbon group of the polycarboxylic acid may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Furthermore, the hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. Furthermore, a hydroxy group or the like may be bonded to a carbon atom constituting the hydrocarbon group.

[0028] The molecular weight of the polycarboxylic acid is not particularly limited, but is preferably 90 to 500, more preferably 90 to 300, and even more preferably 90 to 200. When the molecular weight of the polycarboxylic acid is within this range, it is easily soluble in the liquid medium (particularly water or alcohols) described below. Furthermore, if the molecular weight of the polycarboxylic acid is too high, the amount of silicone that dissolves or disperses in the liquid medium described below tends to decrease, and sufficient water repellency may not be obtained, but when the molecular weight is within the above range, the solubility or dispersibility of the silicone tends to be good.

[0029] Examples of polycarboxylic acids include saturated dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and tartaric acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid; unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, muconic acid, and oxaloacetic acid; cyclic dicarboxylic acids such as 1,4-cyclohexadicarboxylic acid; saturated tricarboxylic acids such as citric acid, isocitric acid, 2-methylpropane-1,2,3-tricarboxylic acid, benzene-1,2,3-tricarboxylic acid, propane-1,2,3-tricarboxylic acid, and oxalosuccinic acid; and trivalent or higher aromatic carboxylic acids such as pyromellitic acid, trimellitic acid, and trimesic acid.

[0030] Among the above, malonic acid, succinic acid, maleic acid, phthalic acid, and fumaric acid are preferred in terms of availability, ease of handling, reactivity, and the like.

[0031] The concentration of the polycarboxylic acid in the water repellent composition is preferably 0.001% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass, and even more preferably 0.05% by mass to 2% by mass. When the concentration of the polycarboxylic acid in the water repellent composition is within this range, the silicone-derived component can be more efficiently fixed to the surface of the substrate, as described above.

[0032] (Liquid Medium) The water repellent composition further contains a liquid medium. The liquid medium may be a liquid (solvent) that is liquid at room temperature and normal pressure and capable of dissolving the silicone and polycarboxylic acid and / or a liquid (dispersion medium) that is capable of dissolving the silicone and polycarboxylic acid. The liquid medium may contain only one specific liquid, or may contain two or more specific liquids. Note that when either or both of the silicone and polycarboxylic acid are solid at room temperature and normal pressure, the liquid medium must contain a solvent that can dissolve them in an amount sufficient to dissolve them.

[0033] Here, the liquid medium may be any component that is liquid at room temperature and normal pressure, but does not include substances equivalent to the liquid silicone or polycarboxylic acid described above. Examples of liquid media include organic solvents and water. The organic solvent is not particularly limited as long as it is capable of dispersing or dissolving the silicone or polycarboxylic acid. Examples of organic solvents include alcohols such as methanol, ethanol, and isopropyl alcohol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; ketones such as acetone; hydrocarbons such as hexane, benzene, toluene, and xylene; and esters such as ethyl acetate and isobutyl acetate. Preferred examples include alcohols such as methanol, ethanol, and isopropyl alcohol.

[0034] The amount of the liquid medium in the water repellent composition is appropriately selected depending on the types of silicone and polycarboxylic acid and the method of contacting the water repellent composition with a substrate. For example, when a substrate is immersed in the water repellent composition to form a water repellent treatment film, the total amount of the liquid medium is preferably 10% by mass to 99.99% by mass, more preferably 60% by mass to 99.99% by mass, and even more preferably 70% by mass to 99.99% by mass, based on the total amount of the water repellent composition.

[0035] On the other hand, the water repellent composition may contain water. The amount of water is preferably 1% by mass to 99% by mass, more preferably 40% by mass to 99% by mass, relative to the total amount of the liquid medium. If the amount of water is too large, the silicone may be difficult to disperse or dissolve in the liquid medium, and the silicone-derived components may not be efficiently fixed to the surface of the substrate. Furthermore, the silicone may locally adhere to the substrate, resulting in a poor appearance. However, as described above, if the amount of water is 99% by mass or less, the silicone is easily dissolved or dispersed uniformly. On the other hand, if the amount of water is too small, the affinity between the silicone and the liquid medium may be excessively good, making it difficult for the silicone to form the aggregate structure shown in FIG. 1B. In contrast, if the amount of water is within the above range, the silicone is adequately dissolved or dispersed in the liquid medium, and an appropriate aggregate structure is easily formed.

[0036] (Other Components) The water repellent composition may contain various additives as long as they do not impair the objects and effects of the present invention. Examples of various additives include silica, insoluble fine powders (organic powders, inorganic powders), calcined kaolin, alumina, antioxidants, antifungal agents, light stabilizers, antibacterial agents, biofouling inhibitors, deodorizers, pigments, flame retardants, antistatic agents, ultraviolet absorbers, infrared absorbers, photochromic agents, dyes, pigments, carbon, talc, mica, metal powders, and metal oxides. The water repellent composition may contain only one of these additives, or may contain two or more of them. However, the total amount of these additives is preferably 10% by mass or less, and more preferably 1% by mass or less, of the total amount of the water repellent composition.

[0037] (Method for preparing water repellent composition) The method for preparing the water repellent composition is not particularly limited as long as the silicone, polycarboxylic acid, and liquid medium are mixed, and the order of mixing is not particularly limited. For example, all components may be mixed at once, or specific components may be mixed in advance and other components may be mixed later.

[0038] (Method for forming water-repellent treated film) The method for forming a water-repellent treated film on a substrate using the water repellent composition is not particularly limited, and examples include spin coating, dip coating, roller coating, bar coating, inkjet coating, gravure coating, spray coating, flow coating, bar code method, dispenser method, nozzle coating, slit coating, die coating, blade coating, knife coating, wire bar coating, screen printing, hand coating, immersion method, etc., or a combination thereof. Preferred are the immersion method, spray coating method, roller coating method, and hand coating method. These methods may be used alone or in combination of two or more.

[0039] The material of the substrate on which the water-repellent treatment film is formed using the water repellent composition of the present invention is not particularly limited, and may be an inorganic material such as metal or ceramic, or an organic material such as fiber, rubber, or plastic. However, a material in which polar groups exist on the substrate surface and are in a reactive state is preferred. The surface of the substrate to be water-repellent treated may be flat or curved. Furthermore, the overall shape of the substrate can be any shape. For example, it may be a plate, film, three-dimensional, fiber, cloth, sponge, or any other shape. The area in which the water-repellent treatment film is formed may be the entire substrate, or may be only a partial area.

[0040] Furthermore, the substrate may be previously subjected to a bonding treatment. Examples of such a bonding treatment include hydrophilization treatments such as corona treatment, plasma treatment, and ultraviolet treatment. Furthermore, the substrate may be previously subjected to a primer treatment using a resin, a silane coupling agent, or tetraalkoxysilane, or may be previously coated with a glass film such as polysilazane.

[0041] When a substrate is immersed in a water repellent composition to form a water repellent film, the substrate is preferably immersed for 1 second to 10 days, more preferably 1 minute to 1 day. As described above, the water repellent composition of the present invention can form a sufficient water repellent film even with immersion for 3 minutes or less. Immersion for 1 minute or more is likely to result in particularly good water repellency. When it is desired to form a water repellent film only on a portion of the substrate, only the desired area may be brought into contact with the water repellent film, or the area where the water repellent film is not to be formed may be masked by various methods and the substrate may be immersed. After the immersion, the substrate is preferably dried as is or washed with laminar water.

[0042] Furthermore, the temperature of the water repellent composition when the substrate is immersed is preferably 0° C. or higher and 100° C. or lower, and more preferably 0° C. or higher and 80° C. or lower. When the temperature of the water repellent composition is within this range, the silicone-derived components are easily fixed to the surface of the substrate.

[0043] Furthermore, when applying the water repellent composition to a substrate, the method of applying the water repellent composition is not particularly limited. The water repellent composition may be applied to the substrate using a brush, cloth, sponge, nonwoven fabric, paper, or the like, or may be sprayed onto the substrate using a spray or the like. After application, the substrate is preferably left to stand for 1 minute to 10 days, more preferably 10 minutes to 5 days, and even more preferably 30 minutes or more. This allows the volatile components remaining on the substrate to completely evaporate, forming a stronger film. The temperature during standing is preferably 0°C or higher and 500°C or lower, more preferably 4°C or higher and 300°C or lower. When the temperature during standing is within this range, the silicone-derived components are more likely to be fixed to the substrate surface. By leaving the substrate standing for the above-mentioned time, the silicone-derived components are more likely to be fixed to the substrate surface.

[0044] Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these.

[0045] [Preparation of Materials] The following materials were used in the examples and comparative examples of the present invention. The viscosity of the silicone was measured using a capillary viscometer in accordance with JIS Z 8803 (2011).

[0046] (Silicone) KF-859 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 60 mm ２ / s, amine equivalent: 6000 g / mol) KF-880 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 650 mm ２ / s, amine equivalent: 1800 g / mol) KF-8004 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 800 mm ２ / s, amine equivalent: 1500 g / mol) KF-8002 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 1100 mm ２ / s, amine equivalent: 1700 g / mol) KF-861 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 3500 mm２ / s, amine equivalent: 2000 g / mol) KF-860 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 250 mm ２ / s, amine equivalent: 7600 g / mol) KF-8005 (side-chain amino-modified silicone represented by the following formula (1), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 1200 mm ２ / s, amine equivalent: 11000 g / mol) KF-6000 (polydimethylsiloxane (both terminal OH), manufactured by Shin-Etsu Silicone Co., Ltd., viscosity at 25°C: 35 mm ２ / s, hydroxyl value: 120 mgKOH / g) KF-6003 (polydimethylsiloxane (OH at both ends), manufactured by Shin-Etsu Silicones Co., Ltd., viscosity at 25°C: 110 mm ２ / s, hydroxyl value: 22 g / mgKOH / g) KF-96-1000CS (polydimethylsiloxane (both terminal CH ３ ), manufactured by Shin-Etsu Silicone Co., Ltd. Viscosity at 25 ° C: 1000 mm ２ / s) KF-96-100CS (polydimethylsiloxane (both terminal CH ３ ), manufactured by Shin-Etsu Silicone Co., Ltd. Viscosity at 25°C: 100 mm ２ / s) KF-96-20CS (polydimethylsiloxane (both terminal CH ３ ), manufactured by Shin-Etsu Silicone Co., Ltd., viscosity at 25°C: 20 mm ２ / s)

[0047] (Polycarboxylic acids) Malonic acid (dicarboxylic acid, solid at room temperature and normal pressure, soluble in IPA and water) Succinic acid (dicarboxylic acid, solid at room temperature and normal pressure, soluble in IPA and water) Fumaric acid (dicarboxylic acid, solid at room temperature and normal pressure, soluble in IPA and water) Maleic acid (dicarboxylic acid, solid at room temperature and normal pressure, soluble in IPA and water) Phthalic acid (dicarboxylic acid, solid at room temperature and normal pressure, soluble in IPA and water) Citric acid (tricarboxylic acid, solid at room temperature and normal pressure, soluble in IPA and water)

[0048] (Monocarboxylic acids) Acetic acid Glycolic acid Lactic acid Propionic acid

[0049] (inorganic acids) Hydrochloric acid Sulfuric acid

[0050] (Other ingredients) IPA (isopropyl alcohol), distilled water, n-decyltrimethoxysilane, ethyl orthosilicate, N-2-aminoethyl-3-aminopropyltrimethoxysilane (KBM603)

[0051] [Examples 1 to 31, Comparative Examples 1 to 9, and Reference Example] Each water repellent composition was prepared by mixing a liquid medium (IPA and / or water), a silicone, and an acid to obtain the composition shown in Tables 1 and 2 below. The state of the water repellent composition after preparation is shown in Tables 1 and 2. Glass substrates were immersed in the prepared water repellent compositions for the times shown in Tables 1 and 2. The removed test pieces were then sprayed with laminar water to wash away any water repellent composition remaining on the substrate surface. In Tables 1 and 2, water repellent compositions with the same composition but with different immersion times are listed as different examples.

[0052]

[0053]

[0054] [Evaluation] The test pieces (after drying) prepared in Examples 1 to 30 and Comparative Examples 1 to 9 were measured for water contact angle and sliding angle by the following methods, and furthermore, the appearance was evaluated. The results are shown in Tables 3 and 4. Furthermore, for the water repellent compositions prepared in Example 31 and Reference Example, test pieces (after drying) prepared immediately after preparation of the water repellent composition and test pieces (after drying) prepared after storing the water repellent composition for one month under storage conditions: room temperature were evaluated. The results are shown in Table 5.

[0055] (Contact Angle Measurement) The test piece that had been subjected to the above treatment was set horizontally in a contact angle meter B100W (manufactured by Asumi Giken Co., Ltd.) 1.7 μl of distilled water was dropped onto the test piece, and then the instantaneous contact angle was measured with the contact angle meter.

[0056] (Sliding Angle Measurement) The test piece that had been subjected to the above treatment was set horizontally on the contact angle meter. After 10 μl of distilled water was dropped onto the test piece, the test piece was gradually tilted, and the angle at which the end point of the water droplet moved 1.2 mm was determined as the sliding angle.

[0057] (Appearance Evaluation) The appearance of the test pieces treated as above was evaluated visually. The evaluation criteria are as follows. △ and above are in the range where there is no problem in practical use. ◎: No oil film, excellent transparency ○: A slight oil film, but excellent transparency △: An oil film in many areas, but excellent transparency ×: An oil film is present, and the substrate surface in the area where the water repellent composition was applied is cloudy

[0058]

[0059]

[0060]

[0061] As shown in Table 4, the water repellent compositions containing silicone, monocarboxylic acid, and a liquid medium (Comparative Examples 1 to 8) all had a sliding angle of 90° or more, and dynamic water repellency could not be sufficiently improved. Furthermore, the water repellent composition containing silicone, sulfuric acid, and a liquid medium (Comparative Example 9) exhibited poor appearance.

[0062] In contrast, as shown in Table 3, the water repellent compositions containing silicone, polycarboxylic acid, and a liquid medium (Examples 1 to 30) all had water contact angles of 71° or more, and sliding angles of less than 90°. In other words, both static and dynamic water repellency were high. Furthermore, the appearance evaluation was within acceptable ranges, resulting in excellent transparency. In particular, when the silicone contained an amino group, the water contact angle was 95° or more, and the appearance evaluation was likely to be rated as good or excellent, resulting in very good results (Examples 1 to 17 and 20 to 25). Here, the dynamic water repellency of the water repellent compositions of the Reference Examples decreased after one month, whereas the static and dynamic water repellency of the water repellent composition of Example 31 remained good even after one month.

[0063] This application claims priority based on Japanese Patent Application No. 2024-022933, filed February 19, 2024. The contents of the specification and drawings of that application are incorporated herein by reference in their entirety.

[0064] According to the water repellent composition of the present invention, a water repellent film having high static and dynamic water repellency can be formed on the surface of a desired substrate in a short time. Furthermore, the surface condition of the substrate is not easily changed by the water repellent film. Therefore, the water repellent composition can be used for the water repellent treatment of various substrates.

Claims

1. A water repellent composition comprising a polycarboxylic acid and a silicone, and being liquid at room temperature and pressure.

2. The water repellent composition according to claim 1, further comprising a liquid medium, wherein the silicone comprises at least one of a liquid silicone that is liquid at room temperature and normal pressure, and a solid silicone that is soluble in the liquid medium and is solid at room temperature and normal pressure.

3. The water repellent composition according to claim 2, wherein the content of the liquid medium is 60% by mass or more and 99.99% by mass or less based on the total amount of the water repellent composition.

4. The water repellent composition according to claim 2, wherein the liquid medium comprises water.

5. The water repellent composition according to claim 2, wherein the liquid medium contains an alcohol.

6. The water repellent composition according to claim 1, wherein the silicone contains an amino group.

7. The water repellent composition according to claim 1, wherein the polycarboxylic acid contains 2 to 5 carboxy groups in one molecule.

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