Dissolving film

Abstract

To provide a liquid repellent film that can enhance liquid repellency to liquids with low surface tension.SOLUTION: A liquid-repellent film 40 has hydrophilic microparticles 41 and a coating 42 covering the hydrophilic microparticles 41. The BET specific surface area of the hydrophilic particles 41 is 15 m2 / g or more. The coating 42 includes a methacrylate copolymer. The methacrylate copolymer is a copolymer of a first monomer, which is a methacrylate monomer having a perfluoroalkyl group, and a second monomer, which is a methacrylate monomer having higher hydrophilicity than the first monomer. The ratio of the constituent units derived from the first monomer in the methacrylate copolymer is from 80 mol% to 99 mol% inclusive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid-repellent film. [Background technology]

[0002] Liquid-repellent films are known that have a surface with irregularities made up of many fine particles. Because the irregularities made up of the fine particles are minute, liquids do not easily penetrate into the irregularities. Therefore, liquids that come into contact with the liquid-repellent film slide off the surface of the film, thereby exhibiting liquid repellency. To enhance the liquid repellency, the liquid-repellent film has a coating containing a fluorine material, and the coating coats the fine particles in a film-like manner (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5114355 [Patent Document 2] Patent No. 5242841 [Patent Document 3] International Publication No. 2019 / 026816 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the ease with which a liquid penetrates into the irregularities varies depending on the surface tension of the liquid, and the lower the surface tension of the liquid, the easier it is for the liquid to penetrate into the irregularities. For example, paints containing organic solvents and detergents containing surfactants have low surface tensions, and from the perspective of improving the liquid repellency against such low-surface-tension liquids, there is still room for improvement in the configuration of the fine particles and coating portion in the liquid-repellent film. [Means for solving the problem]

[0005] The liquid-repellent film for solving the above problems is a liquid-repellent film having hydrophilic fine particles and a coating portion covering the hydrophilic fine particles, wherein the BET specific surface area of ​​the hydrophilic fine particles is 15 m 2 / g or more, the coating portion contains a methacrylate copolymer, the methacrylate copolymer is a copolymer of a first monomer which is a methacrylate monomer having a perfluoroalkyl group and a second monomer which is a methacrylate monomer having higher hydrophilicity than the first monomer, and the ratio of the structural unit derived from the first monomer in the methacrylate copolymer is 80 mol% or more and 99 mol% or less.

[0006] According to the above configuration, the coating property of the hydrophilic fine particles by the coating portion is enhanced, the peeling of the coating portion from the hydrophilic fine particles is suppressed, and the liquid repellency of the coating portion is enhanced. Therefore, on the surface of the liquid repellent film, since the liquid repellency of the coating portion is sufficiently exhibited, even a liquid having a low surface tension and easily entering the unevenness, the liquid is easily repelled on the surface of the liquid repellent film. Therefore, the liquid repellency of the liquid repellent film against a liquid having a low surface tension is enhanced. In particular, since the swelling and dissolution of the coating portion with respect to an aqueous liquid are suppressed, the liquid repellency against a liquid containing water is enhanced.

[0007] In the above configuration, when the total weight of the methacrylate copolymer contained in the liquid repellent film is Mp, the total weight of the hydrophilic fine particles contained in the liquid repellent film is Mf, and the average primary particle diameter of the hydrophilic fine particles is R (nm), the weight Mp, the weight Mf, and the particle diameter R may satisfy 7 < R × (Mp / Mf) < 45. In the above configuration, the weight Mp, the weight Mf, and the particle diameter R may satisfy 12 < R × (Mp / Mf) < 35.

[0008] According to the above configuration, the ratio of the fine particles and the copolymer in the liquid repellent film is suitable in consideration of the particle diameter of the fine particles. That is, it is possible to suppress the amount of the copolymer with respect to the hydrophilic fine particles from being excessive or too small, and the specific surface area of the hydrophilic fine particles from becoming excessively large. Therefore, since the coating portion along the unevenness due to the continuous connection of the hydrophilic fine particles is easily formed appropriately, the water repellency can be improved.

[0009] In the above configuration, the average primary particle diameter of the hydrophilic fine particles may be 20 nm or more. According to the above configuration, the irregularities on the surface of the liquid-repellent film can be easily formed to a size suitable for liquid repellency, thereby improving the liquid repellency of the liquid-repellent film.

[0010] In the above configuration, the second monomer may include a monomer that does not contain a fluorine atom. In the above configuration, the second monomer may include a monomer having any one of a hydroxy group, an amide group, an ether group, a primary amine, a secondary amine, and a tertiary amine.

[0011] According to the above-mentioned configuration, the affinity of the methacrylate copolymer with the hydrophilic particles is enhanced. As a result, the coverage of the hydrophilic particles by the coating portion is improved and peeling of the coating portion from the hydrophilic particles is suppressed. Therefore, the liquid repellency of the liquid-repellent film can be improved.

[0012] In the above configuration, the methacrylate copolymer may not swell or dissolve in an aqueous ethanol solution having a concentration of 50% by mass when the copolymer is in contact with the aqueous ethanol solution for 24 hours.

[0013] According to the above configuration, the coating portion has sufficient resistance to liquids containing ethanol and water, which makes it easier to enhance the liquid-repellent properties of the liquid-repellent film against liquids used in everyday items such as hair care and body care products, cosmetics, and detergents.

[0014] In the above configuration, the methacrylate copolymer may be soluble or dispersible at a concentration of 5% by mass or more in a solvent obtained by mixing ethyl acetate and 1,3-bis(trifluoromethyl)benzene in a weight ratio of 7:3 to 1,3-bis(trifluoromethyl)benzene to ethyl acetate.

[0015] According to the above-mentioned configuration, a mixed solvent of ethyl acetate and 1,3-bis(trifluoromethyl)benzene can be used as a solvent for a coating liquid for forming a liquid-repellent film. By using the mixed solvent as a solvent for a coating liquid, a liquid-repellent film with high liquid-repellent properties can be obtained.

[0016] In the above configuration, the arithmetic mean height Sa of the surface of the liquid-repellent film may be 0.6 μm or more. According to the above-mentioned configuration, since the surface of the liquid-repellent film is formed with unevenness of sufficient height, liquid repellency can be suitably obtained. [Effects of the Invention]

[0017] According to the present invention, it is possible to improve the liquid repellency to liquids with low surface tension. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing an example of a cross-sectional structure of a liquid-repellent article provided with a liquid-repellent film according to an embodiment. [Figure 2] 10A and 10B are diagrams showing another example of the cross-sectional structure of a liquid-repellent article provided with a liquid-repellent film according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] One embodiment of a liquid-repellent film will be described with reference to the drawings. The liquid-repellent film of this embodiment is disposed on the surface of a container or bag that contains the liquid and that comes into contact with the liquid, or on the surface of a sheet or molded product to which it is desired to prevent the adhesion of liquid. An article provided with a liquid-repellent film is a liquid-repellent article.

[0020] [Configuration of liquid-repellent article] 1, the liquid-repellent article 10 includes a support 20, an adhesive layer 30, and a liquid-repellent film 40. The adhesive layer 30 is sandwiched between the support 20 and the liquid-repellent film 40. The liquid-repellent film 40 includes hydrophilic fine particles 41 and a coating portion 42.

[0021] The liquid-repellent article 10 is, for example, a container or bag that contains a liquid such as paint or detergent, or a sheet that is provided on the surface of such a container that comes into contact with the liquid. The material of the support 20 is not particularly limited, and the materials of the support 20 and the adhesive layer 30 may be selected so that the adhesive layer 30 can be adhered to the surface of the support 20. Examples of materials for the support 20 include resins such as polyethylene, polypropylene, polyethylene terephthalate, polystyrene, and acrylic, as well as glass and metal. The support 20 may be in the form of a sheet, or may be a molded product having a shape different from a sheet.

[0022] The adhesive layer 30 is a layer for improving adhesion between the support 20 and the liquid-repellent film 40. The material of the adhesive layer 30 is an adhesive resin such as a polyolefin resin or a polyurethane resin. Note that if sufficient adhesion between the support 20 and the liquid-repellent film 40 can be obtained without using the adhesive layer 30, the liquid-repellent article 10 does not need to include the adhesive layer 30.

[0023] The hydrophilic microparticles 41 are hydrophilic microparticles. The material of the hydrophilic microparticles 41 is, for example, silica or a metal oxide such as titanium oxide. The liquid-repellent film 40 includes at least first hydrophilic microparticles 41 having a nano-order particle size. In addition to the first hydrophilic microparticles 41, the liquid-repellent film 40 may also include second hydrophilic microparticles 41 having a micro-order particle size. The coating portion 42 coats the hydrophilic fine particles 41. The coating portion 42 contains a methacrylate copolymer having a perfluoroalkyl group.

[0024] The surface of the liquid-repellent article 10, i.e., the surface of the liquid-repellent film 40, has minute irregularities along the chain of numerous hydrophilic microparticles 41. Because liquids do not easily penetrate these irregularities, liquids that come into contact with the surface of the liquid-repellent film 40 are more likely to be repelled. If the liquid-repellent film 40 contains second hydrophilic microparticles 41 in addition to the first hydrophilic microparticles 41, the irregularities on the surface of the liquid-repellent film 40 become more complex, and liquids that come into contact with the surface of the liquid-repellent film 40 are more likely to be repelled.

[0025] 2, the adhesive layer 30 may contain large-diameter particles 31 in an adhesive resin. The material of the large-diameter particles 31 is, for example, silica, silicone, acrylic resin, urethane resin, etc. The particle diameter of the large-diameter particles 31 is larger than the particle diameter of the first hydrophilic particles 41, and the large-diameter particles 31 have a particle diameter on the order of microns.

[0026] Since the adhesive layer 30 contains large-diameter microparticles 31, the surface of the adhesive layer 30 has irregularities that correspond to the large-diameter microparticles 31, and the hydrophilic microparticles 41 of the liquid-repellent film 40 are aligned along the irregular surface of the adhesive layer 30. Therefore, the irregularities on the surface of the liquid-repellent film 40 become more complex, making it easier for liquids that come into contact with the surface of the liquid-repellent film 40 to be repelled.

[0027] [Liquid-repellent film composition] The configurations of the hydrophilic fine particles 41 and the coating portion 42 will be described in detail. First, the configuration of the coating portion 42 will be described. The coating portion 42 includes a methacrylate copolymer having a perfluoroalkyl group. This copolymer is a copolymer of a first monomer, which is a methacrylate monomer having a perfluoroalkyl group, and a second monomer, which is a methacrylate monomer having higher hydrophilicity than the first monomer. This copolymer may be a random copolymer or a block copolymer.

[0028] The first monomer has a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms. If the perfluoroalkyl group is linear and has 4 to 6 carbon atoms, this is preferable because it enhances the liquid repellency of the liquid-repellent film 40 and also makes it easy to obtain the monomer or copolymer. A specific example of the first monomer is 2-(perfluorohexyl)ethyl methacrylate.

[0029] The second monomer preferably does not contain a fluorine atom. The second monomer has, for example, any of a hydroxy group, an amide group, an ether group, a primary amine, a secondary amine, a tertiary amine, pyrrolidone, a hydrocarbon chain having six or more carbon atoms and not containing a fluorine atom, and a benzyl group. In particular, to improve the liquid repellency of the liquid-repellent film 40, the second monomer preferably has any of a hydroxy group, an amide group, an ether group, a primary amine, a secondary amine, and a tertiary amine.

[0030] Specific examples of the second monomer are 2-hydroxyethyl methacrylate, 2-(diethylamino)ethyl methacrylate, diethylene glycol dimethacrylate, lauryl methacrylate, and benzyl methacrylate.

[0031] The methacrylate copolymer may be a copolymer of a first monomer and a plurality of types of second monomers having different functional groups.

[0032] The following general formula (1) shows an example of the general formula of a methacrylate copolymer: The copolymer shown in general formula (1) contains, in the repeating structure, a constitutional unit derived from 2-(perfluorohexyl)ethyl methacrylate, which is the first monomer, and a constitutional unit derived from a methacrylate monomer, which is the second monomer.

[0033] [ka] ...General formula (1) In general formula (1), X represents a substituent possessed by the constitutional unit derived from the second monomer, and l and m each independently represent an integer of 1 or greater. As described above, the substituent preferably includes any one of a hydroxy group, an amide group, an ether group, a primary amine, a secondary amine, and a tertiary amine functional group. l represents the number of constitutional units derived from the first monomer, and m represents the number of constitutional units derived from the second monomer.

[0034] The Rf ratio, which is the ratio of the structural units derived from the first monomer in the methacrylate copolymer, is 80 mol % or more and 99 mol % or less. For example, in the copolymer represented by the above general formula (1), if the total number of structural units derived from the first monomer is l and the total number of structural units derived from the second monomer is m, the Rf ratio is expressed as l / (l+m).

[0035] When the Rf ratio is 99 mol % or less, in other words, when the ratio of the constitutional units derived from the second monomer is 1 mol % or more, the affinity between the hydrophilic microparticles 41 and the copolymer increases according to the degree of hydrophilicity of the second monomer. Therefore, when producing the liquid-repellent film 40, the coverage of the hydrophilic microparticles 41 by the coating portions 42 increases, and when using the liquid-repellent film 40, the coating portions 42 become less likely to peel off from the surfaces of the hydrophilic microparticles 41.

[0036] On the other hand, an Rf ratio of 80 mol % or more enhances the liquid repellency of the coating 42. In particular, the copolymer is less likely to swell or dissolve in aqueous liquids, thereby enhancing the liquid repellency to liquids containing water.

[0037] As a result of the above, the liquid repellency of the covering portion 42 is fully exhibited on the surface of the liquid repellent film 40, so that even liquids with low surface tension that tend to penetrate into uneven surfaces are easily repelled by the surface of the liquid repellent film 40.

[0038] Although there is no particular limitation on the liquid that can be repelled by the liquid-repellent film 40, the liquid-repellent film 40 can effectively prevent the adhesion of liquids with high viscosity and low surface tension to its surface. Examples of such liquids include aqueous solutions containing surfactants, hydrocarbon oils, silicone oils, and liquids containing organic solvents.

[0039] For example, the surface tension of liquids containing surfactants, such as detergents and shampoos, is generally about 30 mN / m or less. In contrast, conventional liquid-repellent films made of fine particles and a coating containing a fluorine material have insufficient liquid-repellent properties against liquids with a surface tension of 30 mN / m or less. In the liquid-repellent film 40 of this embodiment, the Rf ratio of the methacrylate copolymer contained in the coating 42 is set to 80 mol % or more and 99 mol % or less, thereby making it possible to obtain good liquid-repellent properties even against liquids with a surface tension of 30 mN / m or less.

[0040] In particular, liquids used as daily necessities, such as hair care products, body care products, cosmetics, detergents, etc., often contain water. The liquid-repellent film 40 of this embodiment has enhanced liquid repellency against liquids containing water, and therefore can be suitably used on the inner surface of containers for liquids used as daily necessities.

[0041] The liquids that the liquid-repellent film 40 is made to repel are not limited to everyday items, but may also be industrial liquids such as paints, fuels, lubricants, adhesives, conductive pastes, liquid rubbers, caulking agents, and asphalt.

[0042] The use of liquid-repellent film 40 on the inner surface of the liquid container prevents the liquid from remaining inside the container when the liquid is removed from the container. As a result, a decrease in the efficiency of removing the liquid is prevented, the burden required for cleaning the areas where the liquid is attached can be reduced, and deterioration of sanitary conditions, such as bacterial growth, caused by remaining liquid is also prevented.

[0043] Furthermore, the liquid-repellent film 40 can repel any liquid that is desired to be prevented from adhering to the surface of an article such as a container, such as a liquid containing medicines, pesticides, or toxic substances, such as an ethanol aqueous solution, in addition to liquids with high viscosity and low surface tension.

[0044] A further description will be given of the properties of the methacrylate copolymer contained in the covering portion 42. The methacrylate copolymer preferably has resistance to an aqueous ethanol solution. Specifically, the methacrylate copolymer preferably has the property of not swelling or dissolving in an aqueous ethanol solution, which means that when a 10 μm-thick polymer film made of the methacrylate copolymer is immersed in a 50% by mass aqueous ethanol solution for 24 hours, the change in thickness of the polymer film compared to before immersion is 2% or less. Furthermore, when a polymer film made of a methacrylate copolymer and having a thickness of approximately 1 μm to 3 μm is immersed in a 50% by mass aqueous ethanol solution for 72 hours and then allowed to air dry, the change in haze of the polymer film compared to before immersion is preferably less than 3%. Haze is measured in accordance with JIS K 7136. A small change in haze indicates that the formation of irregularities on the polymer film surface is suppressed, i.e., indicates that the polymer film swells little when immersed in the aqueous ethanol solution.

[0045] The liquids used in the above-mentioned daily necessities often contain ethanol. The methacrylate copolymer has the property of being difficult to swell or dissolve in an ethanol aqueous solution, which enhances the liquid-repellent properties of the liquid-repellent film 40 against liquids containing ethanol and water. Therefore, the liquid-repellent film 40 is more suitable for use on the inner surface of a container for liquids used in daily necessities.

[0046] In addition, it is preferable that the methacrylate copolymer is soluble or dispersible at a concentration of 5% by mass or more in a solvent obtained by mixing ethyl acetate and 1,3-bis(trifluoromethyl)benzene in a weight ratio of 7:3 to 1,3-bis(trifluoromethyl)benzene to ethyl acetate.

[0047] In this way, if the methacrylate copolymer has solubility or dispersibility in the mixed solvent, the mixed solvent can be used as the solvent for the coating liquid when producing the liquid-repellent film 40. By using the mixed solvent as the solvent for the coating liquid, a liquid-repellent film 40 with high liquid repellency can be obtained.

[0048] The methacrylate copolymer can be obtained by polymerizing the first and second monomers using a known polymerization method. For example, a solution is prepared by adding the monomers and the polymerization initiator to the solvent using 1,3-bis(trifluoromethyl)benzene as the solvent and 2,2'-azobis(isobutyrate)dimethyl as the polymerization initiator, so that the monomer concentration is 40% by mass and the polymerization initiator concentration is 0.2% by mass. The solution is then stirred for 24 hours under an argon gas atmosphere at 70°C to obtain the methacrylate copolymer.

[0049] Alternatively, a methacrylate copolymer that meets the requirements may be selected from commercially available polymers. Examples of available products include SF Coat (SFE-DP02H, SNF-DP20H, SFE-B002H, SNF-B200A) manufactured by AGC Seimi Chemical Co., Ltd., Noxbarrier ST-400 series manufactured by Unimatec Co., Ltd., and Durasurf DH-100 series manufactured by Harves Co., Ltd.

[0050] Next, the structure of the hydrophilic particles 41 will be described. The BET specific surface area of ​​the first hydrophilic particles 41 is 15 m 2 The BET specific surface area of ​​the first hydrophilic fine particles 41 is 300 m / g or more. 2 / g or less. The average primary particle diameter of the first hydrophilic fine particles 41 is preferably 10 nm or more and 100 nm or less, and more preferably 20 nm or more and 100 nm or less.

[0051] If the BET specific surface area and the average primary particle size are within the above ranges, fine irregularities are suitably formed on the surface of the liquid-repellent film 40, thereby improving the liquid repellency. Examples of products that can be used as the first hydrophilic fine particles 41 include the Aerosil series and Aeroxide series manufactured by Nippon Aerosil Co., Ltd., and the HDK series manufactured by Wacker Asahi Kasei Silicone Co., Ltd.

[0052] Further, the average particle diameter of the second hydrophilic fine particles 41 is preferably 1 μm or more and 10 μm or less. When the liquid repellent film 40 contains the first hydrophilic fine particles 41 and the second hydrophilic fine particles 41, the ratio of the total weight of the first hydrophilic fine particles 41 to the total weight of the second hydrophilic fine particles 41 contained in the liquid repellent film 40 is preferably 0.05 or more and 0.5 or less.

[0053] If the average particle diameter of the second hydrophilic fine particles 41 and the total weight of the second hydrophilic fine particles 41 relative to the first hydrophilic fine particles 41 are within the above ranges, irregularities composed of the first hydrophilic fine particles 41 and the second hydrophilic fine particles 41 are preferably formed on the surface of the liquid repellent film 40. Therefore, the liquid repellency is enhanced.

[0054] Examples of products that can be used as the second hydrophilic fine particles 41 include, for example, the silica series manufactured by Fuji Silysia Chemical Ltd., the Nip Seal series manufactured by Tosoh Corporation, and Sun Lovely manufactured by AGC SI TECH Co., Ltd.

[0055] When the total weight of the methacrylate copolymer contained in the liquid repellent film 40 is Mp, the total weight of the first hydrophilic fine particles 41 contained in the liquid repellent film 40 is Mf, and the average primary particle diameter of the first hydrophilic fine particles 41 is R (nm), it is preferable that the weight Mp, the weight Mf, and the particle diameter R satisfy the following mathematical formula (1). 7 < R×(Mp / Mf) < 45 ··· Mathematical formula (1)

[0056] When the value of R×(Mp / Mf) is within the above range, the ratio of the fine particles to the copolymer in the liquid repellent film 40 is suitable in consideration of the particle diameter of the fine particles. For example, when the value of R×(Mp / Mf) is smaller than 45, the amount of the methacrylate copolymer does not become too large relative to the amount of the first hydrophilic fine particles 41, so that it is suppressed that the irregularities due to the continuous arrangement of the hydrophilic fine particles 41 are leveled by the coating portion 42.

[0057] In addition, since the value of R×(Mp / Mf) is greater than 7, the amount of the methacrylate copolymer does not become too small with respect to the amount of the first hydrophilic fine particles 41, so that the first hydrophilic fine particles 41 are more likely to be sufficiently coated by the coating portion 42, and the coating portion 42 along the unevenness due to the alignment of the hydrophilic fine particles 41 is likely to be formed. Further, since it is possible to suppress the particle diameter R of the first hydrophilic fine particles 41 from becoming excessively small, it is possible to suppress the specific surface area of the first hydrophilic fine particles 41 from becoming excessively large. As a result, an increase in the amount of the copolymer required for coating the hydrophilic fine particles 41 is suppressed.

[0058] In order to enhance such an effect, it is preferable that the weight Mp, the weight Mf, and the particle diameter R satisfy the following mathematical formula (2). 12 < R×(Mp / Mf) < 35 ··· Mathematical formula (2)

[0059] When the adhesive layer 30 contains the large-diameter fine particles 31, the average primary particle diameter of the large-diameter fine particles 31 is preferably 1 μm or more and 10 μm or less. Examples of products that can be used as the large-diameter fine particles 31 include, for example, Sunfair manufactured by AGC STEC Co., Ltd., silicone powder KMP series manufactured by Shin-Etsu Silicone Co., Ltd., Guns Pearl manufactured by Aika Industries Co., Ltd., Art Pearl manufactured by Negami Industries Co., Ltd., and the like.

[0060] Examples of products that can be used as the adhesive resin contained in the adhesive layer 30 include Auroren manufactured by Nippon Paper Industries Co., Ltd., Zicen and Sepoljone manufactured by Sumitomo Seika Chemicals Co., Ltd., Unistol manufactured by Mitsui Chemicals, Inc., Arrow Base manufactured by Unitika Ltd., and the like.

[0061] Regarding the surface roughness of the liquid-repellent film 40, the arithmetic mean height Sa of the surface of the liquid-repellent film 40 is preferably 0.6 μm or more. The arithmetic mean height Sa is measured in accordance with ISO 25178. For example, using a laser microscope, the arithmetic mean height Sa is measured for a square region with a side length of 1000 μm on the surface of the liquid-repellent film 40. [[ID=If the arithmetic mean height Sa of the surface of the liquid-repellent film 40 is 0.6 μm or more, the surface of the liquid-repellent film 40 has sufficient irregularities, so that liquid repellency can be suitably obtained.

[0062] [Method of manufacturing liquid-repellent film] A method for manufacturing the liquid-repellent film 40 and the liquid-repellent article 10 will now be described. First, a coating liquid in which the material for the adhesive layer 30 is dissolved or dispersed is applied to the surface of the support 20, and the formed film is dried to form the adhesive layer 30. The coating liquid can be applied by any known coating method, such as bar coating, spraying, gravure coating, or die coating.

[0063] Next, a coating liquid in which the material of the liquid-repellent film 40 is dissolved or dispersed is applied to the surface of the adhesive layer 30, and the formed film is dried to form the liquid-repellent film 40. The coating liquid can be applied by any known coating method, such as bar coating, spraying, gravure coating, or die coating.

[0064] The coating liquid for forming the liquid-repellent film 40 can be obtained, for example, by mixing a dispersion liquid in which hydrophilic microparticles 41 are dispersed with a solution in which a methacrylate copolymer is dissolved. The dispersion medium of the dispersion liquid is not particularly limited as long as it can disperse the hydrophilic microparticles 41, and the solvent of the solution is not particularly limited as long as it can dissolve the methacrylate copolymer. However, from the viewpoint of enhancing the liquid repellency of the liquid-repellent film 40, it is preferable that the polarity of the coating liquid medium containing the dispersion medium and solvent is low, since this facilitates coating of the hydrophilic particles 41 with the methacrylate copolymer. Specifically, the dispersion medium in the dispersion of the hydrophilic particles 41 is preferably ethyl acetate, propyl acetate, or methyl ethyl ketone, and the solvent for the solution of the methacrylate copolymer is preferably 1,3-bis(trifluoromethyl)benzene. Furthermore, in order to keep the polarity of the coating liquid low, it is preferable to prepare the coating liquid so that the weight of the solvent contained in the coating liquid is greater than the weight of the dispersion medium.

[0065] According to this manufacturing method, a liquid-repellent film 40 having high liquid repellency can be obtained without going through a complicated process or a costly process such as a process of bonding the fine particles and the copolymer.

[0066] [Example] The liquid-repellent film and the liquid-repellent article described above will be explained using specific examples and comparative examples.

[0067] (material) The materials used in the examples and comparative examples and the methods for preparing the coating solutions for forming the adhesive layer and the liquid-repellent film are as follows. <Support> Polyethylene terephthalate film (thickness 50 μm)

[0068] <Coating liquid for adhesive layer formation> The following two types of coating liquids for forming adhesive layers were prepared. Adhesive layer A1: A polyolefin resin (Arrowbase SB5230N (solid content 50%) manufactured by Unitika Ltd.) was used as the adhesive resin, and 6.7 g of the adhesive resin was dissolved in a mixed solvent of 10.0 g of water and 50.0 g of isopropanol to prepare a coating liquid for forming the adhesive layer. The solid content in the coating liquid was 3.3 mass %.

[0069] Adhesive layer A2: A polyolefin resin (Arrowbase SB5230N, manufactured by Unitika Ltd., solid content 50%) was used as the adhesive resin, and acrylic resin particles (Art Pearl SE-010T, manufactured by Negami Chemical Industrial Co., Ltd., average primary particle diameter 10 μm) were used as the large-diameter particles. 6.7 g of adhesive resin and 2.9 g of large-diameter particles were mixed with a mixed solvent of 40.5 g of water and 50.0 g of isopropanol to prepare a coating liquid for forming an adhesive layer. The solid content of the coating liquid was 20.0 mass %.

[0070] <Coating liquid for forming liquid-repellent film> Hydrophilic particles were mixed into ethyl acetate at a concentration of 8% by mass, and the mixture was stirred using a magnetic stirrer to prepare a particle dispersion.

[0071] A methacrylate copolymer was dissolved in 1,3-bis(trifluoromethyl)benzene at a concentration of 2% by mass to prepare a polymer solution. The fine particle dispersion and the polymer solution were mixed and stirred using a magnetic stirrer to prepare a coating solution for forming a liquid-repellent film. 1,3-bis(trifluoromethyl)benzene or ethyl acetate was added as a dilution solvent as needed so that the solid content in the coating solution was 3 mass % and the weight ratio of 1,3-bis(trifluoromethyl)benzene to ethyl acetate was 7:3.

[0072] The following five types of hydrophilic particles were used. New aqueous microparticles F1: Silica particles (Aerosil 50 manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 30 nm, BET specific surface area 50 m 2 / g) Hydrophilic particles F2: Silica particles (Aerosil 130 manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 16 nm, BET specific surface area 130 m 2 / g) Hydrophilic microparticles F3: Silica particles (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 12 nm, BET specific surface area 200 m 2 / g) Hydrophilic microparticles F4: Titanium oxide particles (Aeroxide P25 manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 20 nm, BET specific surface area 40 m 2 / g) Hydrophilic particles F5: Silica particles (Fuji Silysia 450, average primary particle diameter 8 μm)

[0073] The 14 types of methacrylate copolymers used are shown in Table 1. All of these copolymers are random copolymers. Table 1 shows: 1 The composition ratio of the monomers in each copolymer calculated from H-NMR measurements and the test results of solvent resistance and solubility are shown.

[0074] [Table 1]

[0075] The abbreviations in Table 1 correspond to the following monomers: RfMA: 2-(perfluorohexyl)ethyl methacrylate HEMA: 2-hydroxyethyl methacrylate DEAEMA: 2-(diethylamino)ethyl methacrylate DEGDMA: Diethylene glycol dimethacrylate LaMA: Lauryl methacrylate

[0076] 1 H-NMR measurements were carried out using a solvent in which hexafluorobenzene and deuterated chloroform were mixed in a weight ratio of 6:4 to hexafluorobenzene. The chemical shift values ​​used to measure the monomer composition ratio are shown below. RfMA: 4.47 ppm (2H) or 2.69 ppm (2H) HEMA: 4.27 ppm (2H) or 3.97 ppm (2H) DEAEMA: 4.09 ppm (2H) or 2.78 ppm (2H) DEGDMA: 3.76 ppm (4H)

[0077] The test method for solvent resistance and solubility is as follows. Solvent resistant For each copolymer, the polymer solution was applied to a glass plate and dried to form a coating film with a thickness of approximately 1 μm to 3 μm. The coating film was immersed in a 50% by mass aqueous ethanol solution for 72 hours and then air-dried.

[0078] The change in haze of the coating film before and after immersion in an ethanol aqueous solution was measured. Haze measurements were performed using a haze meter HM-150 manufactured by Murakami Color Research Laboratory. A haze change of less than 3% was considered to be sufficient solvent resistance and rated as "Good," while a haze change of 3% or more was considered to be insufficient solvent resistance and rated as "Poor."

[0079] ·Solubility For each copolymer, 0.5 g of the copolymer was added to a solution prepared by mixing 7 g of ethyl acetate and 3 g of 1,3-bis(trifluoromethyl)benzene, and the mixture was placed in an environment of 20° C. When the entire amount of the copolymer dissolved in the solution, the solubility was deemed good and evaluated as "Good", and when at least a part of the copolymer did not dissolve, the solubility was deemed poor and evaluated as "Poor".

[0080] (Manufacturing method) The adhesive layer-forming coating liquid was applied to the surface of the support using a wire bar or by spraying, and the resulting film was dried under hot air at 100°C for 90 seconds to form an adhesive layer. The coating amount of the adhesive layer-forming coating liquid was approximately 1 g / m. 2 is.

[0081] Next, a liquid-repellent coating solution was applied to the surface of the adhesive layer using a wire bar, and the resulting film was dried under hot air at 100°C for 90 seconds to form a liquid-repellent film. The amount of the liquid-repellent coating solution applied was approximately 1 g / m. 2 is.

[0082] (Configurations of Examples and Comparative Examples) Using the above-mentioned materials and manufacturing method, the combinations of adhesive layers, hydrophilic particles, and methacrylate copolymers, and the ratios of hydrophilic particles to methacrylate copolymers were changed to obtain Examples 1 to 29 and Comparative Examples 1 to 6. Table 2 shows the type of copolymer, hydrophilic particles, and adhesive layer, the value of R×(Mp / Mf), and the arithmetic mean height Sa for each Example and Comparative Example.

[0083] [Table 2]

[0084] In Example 14, in which the liquid-repellent membrane contains first hydrophilic microparticles and second hydrophilic microparticles, the ratio of the total weight of the first hydrophilic microparticles to the total weight of the second hydrophilic microparticles contained in the liquid-repellent membrane is 0.15.

[0085] In addition, in Examples 6, 13, 21, and 26, a spray method was used to apply the adhesive layer-forming coating liquid, while in the other Examples and Comparative Examples, a wire bar was used to apply the adhesive layer-forming coating liquid.

[0086] The arithmetic mean height Sa of the liquid-repellent film was measured using an Olympus OLS-4100 confocal laser microscope. The magnification of the lens used was 50x. Prior to the measurement, the liquid-repellent film may be subjected to platinum sputtering for 100 seconds.

[0087] (Liquid repellency evaluation) For each example and comparative example, the liquid repellency was evaluated against seven types of liquid. The types of liquid and the evaluation method are as follows.

[0088] <Liquid> Liquid L1: Ethanol aqueous solution (concentration: 40% by mass, surface tension: 29.9 mN / m) Liquid L2: Ethanol aqueous solution (concentration: 60% by mass, surface tension: 27.0mN / m) Liquid L3: Ethanol aqueous solution (concentration: 80% by mass, surface tension: 24.8 mN / m) Liquid L4: Hexadecane (surface tension: 27.6 mN / m) Liquid L5: Decane (surface tension: 23.9 mN / m) Liquid L6: Shampoo (Kao Merit Shampoo) Liquid L7: Methylphenyl silicone oil (KF-54 manufactured by Shin-Etsu Silicone Co., Ltd., surface tension: 25.2 mN / m)

[0089] <Evaluation method> For each example and comparative example, 0.5 mL of liquid was dropped onto the surface of a liquid-repellent film on a support placed on a horizontal plane, and the support was then tilted 45° relative to the horizontal plane, and the surface of the liquid-repellent film was visually observed. A case in which the droplet slid down the surface of the liquid-repellent film and no liquid was observed adhering to the surface of the liquid-repellent film was evaluated as "Good." A case in which a small amount of liquid was observed adhering to the surface of the liquid-repellent film but not spreading in a film-like form was evaluated as "Good." A case in which a film-like spread of the liquid was observed adhering to the drop of the liquid was evaluated as "Poor."

[0090] <Evaluation results> Table 3 shows the evaluation results of the liquid repellency for each liquid for each example and each comparative example.

[0091] [Table 3]

[0092] As shown in Table 1, the Rf ratios of copolymers P1, P5, P9, P11, P12, and P14 are smaller than 80 mol % or larger than 99 mol %. As shown in Table 3, Comparative Examples 1 to 6, which used these copolymers, exhibited insufficient liquid repellency with respect to any of liquids L1 to L7, each of which had a surface tension of 30 mN / m or less.

[0093] On the other hand, in Examples 1 to 29 using copolymers P2, P3, P4, P6, P7, P8, P10 and P13 having an Rf ratio of 80 mol % or more and 99 mol % or less, good liquid repellency was obtained at least with respect to the liquid L1.

[0094] The examples will be considered in detail below. As shown in Tables 2 and 3, Examples 1, 4, 15, 16, 19, 27, 28, and 29 differ only in the type of copolymer. Among these, Example 29 has lower liquid repellency than the others, i.e., it is liquid-repellent to a smaller number of liquids. In Example 29, the second monomer used to produce the copolymer has a long hydrocarbon chain, whereas in the other examples, the second monomer has a hydroxyl group or an amino group. Therefore, it is suggested that, in order to improve liquid repellency, it is preferable for the second monomer to have a highly hydrophilic group such as a hydroxyl group or an amino group.

[0095] From Table 1, in the constituent units of the methacrylate copolymer, when the ratio of the first monomer exceeds 99 mol%, the solubility of the copolymer in the solvent decreases. On the other hand, when the ratio of the first monomer is less than 80 mol% and the ratio of the second monomer having a highly hydrophilic group increases, it can be seen that the resistance of the copolymer to the ethanol aqueous solution decreases. In copolymers P13 and P14 in which the second monomer has a long hydrocarbon chain, although resistance to the ethanol aqueous solution can be obtained even when the ratio of the second monomer increases, the coating property of the hydrophilic fine particles decreases, so it is considered that there is a limit to the improvement of liquid repellency as in Example 29.

[0096] Therefore, when the Rf ratio is 80 mol% or more and 99 mol% or less, and the second monomer has a highly hydrophilic group such as a hydroxy group or an amino group, the solubility of the copolymer in the solvent, the resistance to the ethanol aqueous solution, and the coating property of the hydrophilic fine particles are all improved, and it is considered that a liquid repellent film with high liquid repellency can be formed.

[0097] Also, in Examples 2, 3, 4, 7, and 8, only the ratio of the hydrophilic fine particles to the methacrylate copolymer is different, that is, the value of R×(Mp / Mf) is different. Among these, the liquid repellency of Examples 2 and 8 in which the value of R×(Mp / Mf) is less than 7 or greater than 45 is lower than the others. Therefore, it is suggested that it is preferable that 7 < R×(Mp / Mf) < 45 is satisfied for improving the liquid repellency. The same can be said from Examples 17, 18, 19, 22, and 23. <​Among Examples 2 to 8, Example 5, in which the adhesive layer contains large-diameter fine particles, and Example 6, in which the adhesive layer was formed by a spray method, exhibited increased surface roughness of the liquid-repellent film, resulting in high liquid repellency. That is, good liquid repellency was obtained, especially against liquids L5 and L7, which have low surface tensions. The same can be said for Examples 20 and 21. Note that while the surface tension of liquid L3 is low, similar to that of liquids L5 and L7, the copolymers of each Example exhibited enhanced resistance to aqueous ethanol solutions, which is likely why many Examples exhibited high liquid repellency against liquid L3. Furthermore, in Examples 9 and 24, titanium oxide particles were used as hydrophilic fine particles, which tended to form large aggregates in the coating liquid compared to when silica particles were used. This also allowed for the production of liquid-repellent films with high surface roughness.

[0099] In Examples 10 to 14, hydrophilic particles with an average primary particle diameter of less than 20 nm were used, meaning that the size of the hydrophilic particles contained in the liquid-repellent film was smaller than in Examples 2 to 9. Therefore, as in Example 10, the value of R×(Mp / Mf) and the surface roughness tend to be small, and in such cases, the liquid repellency tends to be low. On the other hand, as in Examples 11 to 14, it was found that the liquid repellency could be improved by adjusting the ratio of hydrophilic particles to methacrylate copolymer, adding large-diameter particles to the adhesive layer, changing the coating method of the adhesive layer, or adding second hydrophilic particles. The same can be said for Examples 25 and 26.

[0100] As described above in the embodiments and examples, the liquid-repellent film 40 can provide the following effects. (1) In the methacrylate copolymer included in the coating portion 42, the ratio of the structural unit derived from the first monomer having a perfluoroalkyl group is 80 mol% or more and 99 mol% or less. Thereby, the coating property of the hydrophilic fine particles 41 by the coating portion 42 is enhanced, peeling of the coating portion 42 from the hydrophilic fine particles 41 is suppressed, and the liquid repellency of the coating portion 42 is enhanced. Therefore, on the surface of the liquid repellent film 40, since the liquid repellency of the coating portion 42 is sufficiently exhibited, even a liquid having a low surface tension and easily entering the unevenness, the liquid is easily repelled on the surface of the liquid repellent film 40. Therefore, the liquid repellency of the liquid repellent film 40 against a liquid having a low surface tension is enhanced. In particular, since swelling and dissolution of the coating portion 42 with respect to an aqueous liquid are suppressed, the liquid repellency against a liquid containing water is enhanced.

[0101] (2) The weight Mp of the methacrylate copolymer, the weight Mf of the first hydrophilic fine particles 41, and the average primary particle diameter R (nm) of the first hydrophilic fine particles 41 satisfy 7 < R×(Mp / Mf) < 45. Thereby, the ratio of the fine particles and the copolymer in the liquid repellent film 40 becomes suitable in consideration of the particle diameter of the fine particles. That is, it is suppressed that the amount of the copolymer becomes excessive or too small with respect to the first hydrophilic fine particles 41, and the specific surface area of the first hydrophilic fine particles 41 becomes excessively large. Therefore, since the coating portion 42 along the unevenness due to the continuous arrangement of the hydrophilic fine particles 41 is easily formed appropriately, the water repellency can be improved. Further, when 12 < R×(Mp / Mf) < 35 is satisfied, the above effect is enhanced.

[0102] (3) When the average primary particle diameter of the first hydrophilic fine particles is not less than 20 nm, the unevenness on the surface of the liquid repellent film 40 is easily formed to a size suitable for liquid repellency. Therefore, the liquid repellency of the liquid repellent film 40 can be improved.

[0103] (4) At least one of the second monomers is a monomer that does not contain a fluorine atom, thereby enhancing the affinity of the methacrylate copolymer with the hydrophilic fine particles 41. As a result, the coverage of the hydrophilic fine particles 41 by the coating portions 42 is enhanced, and peeling of the coating portions 42 from the hydrophilic fine particles 41 is also suppressed. This improves the liquid repellency of the liquid-repellent film 40. In particular, if at least one of the second monomers is a monomer having any of a hydroxy group, an amide group, an ether group, a primary amine, a secondary amine, and a tertiary amine, the above effect is enhanced.

[0104] (5) If the arithmetic mean height Sa of the surface of the liquid-repellent film 40 is 0.6 μm or more, the surface of the liquid-repellent film 40 has unevenness of sufficient height, so that liquid repellency can be suitably obtained. (6) The methacrylate copolymer has the property of not swelling or dissolving in a 50% by mass aqueous ethanol solution when the copolymer is in contact with the aqueous ethanol solution for 24 hours, which provides sufficient resistance of the coating 42 to liquids containing ethanol and water, thereby enhancing the liquid repellency of the liquid-repellent film 40 against liquids used in everyday products.

[0105] (7) The methacrylate copolymer can be dissolved or dispersed at a concentration of 5% by mass or more in a solvent obtained by mixing ethyl acetate and 1,3-bis(trifluoromethyl)benzene in a weight ratio of 7:3. This allows the mixed solvent of ethyl acetate and 1,3-bis(trifluoromethyl)benzene to be used as a solvent for a coating liquid for forming the liquid-repellent film 40. By using the mixed solvent as the solvent for the coating liquid, a liquid-repellent film 40 with high liquid repellency can be obtained. [Explanation of symbols]

[0106] 10...Liquid repellent article 20...Support 30...adhesive layer 31...Large particle 40...Liquid repellent film 41...Hydrophilic fine particles 42...Covering part

Claims

1. A liquid-repellent membrane having one type of hydrophilic fine particles and a coating portion that covers the hydrophilic fine particles, The BET specific surface area of ​​the hydrophilic fine particles is 15 m ２ / g or more, the average primary particle diameter of the hydrophilic fine particles is 10 nm or more and 100 nm or less; the covering portion includes a methacrylate copolymer, the methacrylate copolymer is a copolymer of a first monomer which is a methacrylate monomer having a perfluoroalkyl group and a second monomer which is a methacrylate monomer having higher hydrophilicity than the first monomer; a ratio of the constitutional unit derived from the first monomer in the methacrylate copolymer is 86 mol% or more and 98 mol% or less; the hydrophilic fine particles are fine particles made of silica or titanium oxide, the first monomer is 2-(perfluorohexyl)ethyl methacrylate, and the second monomer is at least one of 2-hydroxyethyl methacrylate and 2-(diethylamino)ethyl methacrylate; When the total weight of the methacrylate copolymer contained in the liquid-repellent film is Mp, the total weight of the hydrophilic fine particles contained in the liquid-repellent film is Mf, and the average primary particle diameter of the hydrophilic fine particles is R (nm), the weight Mp, the weight Mf, and the particle diameter R satisfy the following mathematical formula (1): 7<R×(Mp / Mf)<45 Formula (1) Liquid repellent film.

2. The weight Mp, the weight Mf, and the particle diameter R satisfy the following formula (2): 12<R×(Mp / Mf)<35 ... Formula (2) The liquid-repellent film according to claim 1 .

3. The average primary particle diameter of the hydrophilic fine particles is 20 nm or more. The liquid-repellent film according to claim 1 or 2.

4. The methacrylate copolymer does not swell or dissolve in an aqueous ethanol solution having a concentration of 50% by mass when the copolymer is in contact with the aqueous ethanol solution for 24 hours. The liquid-repellent film according to any one of claims 1 to 3.

5. The methacrylate copolymer can be dissolved or dispersed at a concentration of 5% by mass or more in a solvent obtained by mixing ethyl acetate and 1,3-bis(trifluoromethyl)benzene in a weight ratio of ethyl acetate to 1,3-bis(trifluoromethyl)benzene of 7:

3. The liquid-repellent film according to any one of claims 1 to 4.

6. The arithmetic mean height Sa of the surface of the liquid-repellent film is 0.6 μm or more. The liquid-repellent film according to any one of claims 1 to 5.

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