JP2018203895A - Hydrophilic oil repellent coating film and antifouling coated body - Google Patents

Abstract

To provide a hydrophilic oil repellent coating film capable of achieving hydrophilic oil repellency and achieving self-cleaning property which makes removal easy even when stain is adhered.SOLUTION: A hydrophilic oil repellent coating film is at least constituted by hydrophilic nanoparticles having average particle diameter of 100 nm or less, has convexoconcave with arithmetic average roughness Ra in a range of 2.5 to 100 nm on a surface of the hydrophilic oil repellent coating film, and further contains at least one of a fluorine compound and a silicon compound as an oil repellent component, and has water contact angle of less than 15°, and oil contact angle of over 15°.SELECTED DRAWING: None

Description

  In the present invention, a hydrophilic oil-repellent coating film capable of imparting both hydrophilicity and oil repellency to the surface of an object to be coated, and the hydrophilic oil-repellent coating film are formed on the surface to be antifouling. It relates to an antifouling covering.

  Conventionally, in order to realize the antifouling property of an article, hydrophilic oil repellency is imparted to the surface of the article. Such imparting of hydrophilic oil repellency typically includes a technique of forming a film having hydrophilic oil repellency on the surface of an article using a fluorine-containing compound.

  For example, Patent Document 1 discloses hydrophilic oil repellency by performing discharge treatment in an atmosphere containing a perfluorocarbon and an oxygen-containing compound having an oxygen atom and having neither a C—H bond nor a halogen atom. A method for forming a film having the same is disclosed. The degree of hydrophilic oil repellency in this film is adjusted by the ratio of the number of oxygen atoms and the number of fluorine atoms present in the discharge treatment atmosphere.

  Patent Document 2 discloses a hydrophilic oil repellency imparting agent comprising an organic compound having a fluorine atom and an alkylene oxide group, and a phosphate ester compound having a specific structure, and this hydrophilic oil repellency imparting agent and curability are disclosed. A composition containing a monomer and / or an oligomer is applied to form a hydrophilic oil-repellent coating film. Specific examples of the hydrophilic oil repellency imparting agent include a copolymer containing at least one fluorine atom-containing (meth) acrylate and an alkylene oxide-containing (meth) acrylate as a copolymer component, or a fluorine atom and an alkylene oxide group. In addition, low molecular organic compounds having a molecular weight of about 4000 or less are exemplified. In these hydrophilic oil repellency imparting agents, the proportion of the fluorine atom content in the molecule or the proportion of the total amount of alkylene oxide groups is limited from the viewpoint of improving the hydrophilic oil repellency.

  Further, Patent Document 3 discloses a hydrophilic oil repellent that is a perfluoroalkyl group-containing compound having a specific structure, and Patent Document 4 discloses a hydrophilic oil repellent that is a perfluoropolyether group-containing compound having a specific structure. Document 5 discloses a hydrophilic oil repellent that is a fluorine-based compound containing a perfluoroalkyl group and / or a perfluoroalkylene group having a specific structure.

  In Patent Document 3 or 4, a surface coating material containing the hydrophilic oil repellent and a solvent is applied to form a coating film (coating film), thereby imparting hydrophilic oil repellency to the surface of the article. In Patent Document 5, a surface covering material including a hydrophilic oil repellent, a binder, and a solvent is formed. All of the hydrophilic oil repellents disclosed in these patent documents contain an oil repellency-imparting group (oil repellency-imparting group) and a hydrophilic property-imparting group (hydrophilicity-providing group) in order to exert hydrophilic oil repellency. It is out.

  In addition, as another technique for realizing the antifouling property of an article, a technique is known in which a film that exposes a hydrophilic part and a hydrophobic part of a minute region independently of each other on the surface of the article is known. Yes. For example, Patent Document 6 discloses a coating composition containing ultrafine silica particles having an average particle size of 15 nm or less and fluororesin particles preferably in the range of 50 to 500 nm, which are blended at a predetermined mass ratio. It is disclosed.

  By forming a coating film (coating film) using this coating composition, a hydrophilic portion caused by silica ultrafine particles and a hydrophobic portion caused by fluororesin particles are mixed in a balanced manner. In Patent Document 6, this prevents the adhesion of both hydrophilic dirt and lipophilic dirt.

JP 2008-031511 A International Publication No. 2015/046375 Japanese Patent Application Laid-Open No. 2006-074828 JP, 2006-074830, A International Publication No. 2016/017761 International Publication No. 2008/087877

  Here, in recent years, self-cleaning property (self-cleaning function) has attracted attention from the viewpoint of improving the antifouling property of articles. Typically, the self-cleaning property can be defined as being able to easily remove dirt by washing with water.

  However, in Patent Documents 1 to 6 described above, such self-cleaning property is not studied at all, and it is difficult to further improve the antifouling property of the article.

  The present invention has been made in order to solve such problems, and can achieve hydrophilic oil repellency and can realize self-cleaning properties that are easy to remove even if dirt adheres. An object is to provide a possible hydrophilic oil-repellent coating film.

  As a result of intensive studies by the inventors, when forming a coating film by combining a hydrophilic nanoparticle such as silica with an oil repellent component such as a fluorine compound, by controlling the degree of unevenness on the surface, Originally found that it is possible to achieve hydrophilic oil repellency, effectively suppress or prevent the adhesion of dry dirt, and to make it easy to remove even if dirt adheres. The invention has been completed.

  That is, the hydrophilic oil-repellent coating film according to the present invention is a coating film composed of at least hydrophilic nanoparticles having an average particle diameter of 100 nm or less in order to solve the above-described problems. The surface of the covering film has irregularities with an arithmetic average roughness Ra in the range of 2.5 to 100 nm, and further contains at least one of a fluorine compound and a silicon compound as an oil repellent component, and a water contact angle of 15 °. And the oil contact angle is more than 15 °.

  According to the said structure, the coating film which has the unevenness | corrugation in the said range on the surface is formed using the hydrophilic nanoparticle and the oil-repellent component. As a result, it is possible to realize good hydrophilic oil repellency and to realize self-cleaning properties that facilitate removal even if dirt is attached.

  In addition, the present invention includes an antifouling coating having a structure in which a surface to be antifouling in a coating object is coated with the hydrophilic oil-repellent coating film having the above-described configuration.

  The present invention provides a hydrophilic oil-repellent coating film that can achieve hydrophilic oil-repellent properties and can achieve self-cleaning properties that can be easily removed even if dirt is attached. There is an effect that can be done.

  The hydrophilic oil-repellent coating film according to the present disclosure is a coating film composed at least of hydrophilic nanoparticles having an average particle diameter of 100 nm or less, and has an arithmetic average roughness Ra on the surface of the coating film. While having irregularities in the range of 2.5 to 100 nm, and further containing at least one of a fluorine compound and a silicon compound as an oil repellent component, the water contact angle is less than 15 °, and the oil contact angle is 15 The configuration is over °.

  According to the said structure, the coating film which has the fine unevenness | corrugation in the said range on the surface is formed using the hydrophilic nanoparticle and the oil-repellent component. As a result, it is possible to realize good hydrophilic oil repellency and to realize self-cleaning properties that facilitate removal even if dirt is attached.

  In the hydrophilic oil-repellent coating film having the above-described configuration, the nanoparticle may have an average particle size in the range of 5 to 100 nm.

  According to the said structure, if the average particle diameter of a nanoparticle is in the said range, a fine surface unevenness | corrugation can be implement | achieved more favorably.

  Further, in the hydrophilic oil-repellent coating film having the above-described configuration, the nanoparticles are composed of metal nanoparticles, inorganic oxide nanoparticles, inorganic nitride nanoparticles, inorganic chalcogenide nanoparticles, and (meth) acrylic resin nanoparticles. The structure which is at least 1 sort (s) selected from the group which consists of may be sufficient.

  According to the said structure, if a nanoparticle is a particle | grains which consist of at least any material of the said group, a favorable hydrophilic oil-repellent coating film can be formed.

  Further, the hydrophilic oil-repellent coating film having the above-described structure may have a film thickness of 500 nm or less.

  According to the said structure, the electrical charging property of a hydrophilic oil-repellent coating film can be reduced favorably, and adhesion of a dry dirt can be suppressed or prevented favorably.

  Moreover, in the hydrophilic oil-repellent coating film having the above-described structure, the oil-repellent component may have an average molecular weight of 10,000 or less and not formed into particles.

  According to the said structure, while becoming easy to form fine unevenness | corrugation in the surface of a hydrophilic oil-repellent coating film, it becomes easy to provide favorable oil repellency to the surface. Therefore, it can realize good hydrophilic oil repellency, can effectively suppress or prevent the adhesion of dry dirt, and can also realize self-cleaning properties that make it easy to remove even if dirt adheres. It becomes.

  In the hydrophilic oil-repellent coating film having the above-described structure, the oil-repellent component may be contained within a range of 0.1 to 10% by weight when the total weight is 100% by weight. Good.

  According to the above configuration, on the surface of the hydrophilic oil-repellent coating film, it is possible to achieve both the achievement of fine irregularities derived from nanoparticles and the achievement of oil repellency (oil repellency) by the oil-repellent component. Become.

  In addition, the hydrophilic oil-repellent coating film having the above-described configuration includes an adhesive component composed of at least a material having an affinity for the nanoparticles in addition to the nanoparticles and the oil-repellent component. Also good.

  According to the said structure, while being able to improve the intensity | strength or durability of a hydrophilic oil-repellent coating film, it becomes easy to maintain the fine unevenness | corrugation of a surface, and improves the effect which suppresses or prevents adhesion of dry dirt. be able to.

Further, the hydrophilic oil-repellent coating film having the above-described configuration may have a surface resistivity of 10 ¹³ Ω / □ or less.

  According to the above-described configuration, the chargeability of the hydrophilic oil-repellent coating film can be reduced satisfactorily, so that the adhesion of dry dirt can be suppressed or prevented satisfactorily.

  The antifouling covering according to the present disclosure has a configuration in which a surface to be antifouling in a covering object is covered with the hydrophilic oil-repellent coating film having the above-described configuration. As a result, the antifouling coating can effectively suppress or avoid the adhesion of dry dirt, and can realize self-cleaning properties that facilitate removal even if dirt adheres.

In the antifouling covering body having the above-described configuration, the covering object may be an electric product or a part thereof. Thereby, the favorable antifouling process can be performed with respect to the surface of an electric product or its components.
Hereinafter, a typical configuration example of the present disclosure will be specifically described.

[Hydrophilic oil repellent coating film]
The hydrophilic oil-repellent coating film according to the present disclosure is composed of at least hydrophilic nanoparticles having an average particle diameter of 100 nm or less and contains an oil-repellent component described later, and has an arithmetic average roughness on the surface thereof. Ra is a film having irregularities in the range of 2.5 to 100 nm. The kind of nanoparticles constituting the hydrophilic oil-repellent coating film is not particularly limited as long as it is hydrophilic, but typically, metal nanoparticles, inorganic oxide nanoparticles, inorganic nitride nanoparticles, inorganic chalcogenides Examples thereof include nanoparticles (excluding inorganic oxide nanoparticles), (meth) acrylic resin nanoparticles, and the like.

Specifically, for example, as the metal nanoparticles, Group 11 elements of the periodic table such as gold (Au), silver (Ag), copper (Cu), iron platinum (FePt) or alloys thereof; Examples include metal elements for plating other than Group 11 elements of the periodic table, such as Group 10 elements) and tin (Sn, Group 14 elements). Examples of the inorganic oxide nanoparticles include silica (silicon oxide, SiO ₂ ), yttrium oxide (Y ₂ O ₃ ), barium titanate (BaTiO ₃ ), antimony-doped tin oxide (ATO), and titanium oxide (TiO ₂ ). And indium oxide (In ₂ O ₃ ). Examples of the inorganic nitride nanoparticles include gallium nitride (GaN). Examples of the inorganic chalcogenide nanoparticles include cadmium selenide (CdSe). Examples of (meth) acrylic resin nanoparticles include polymethyl methacrylate (PMMA).

  These nanoparticles basically constitute a hydrophilic oil-repellent coating film by only one kind, but a plurality of kinds can be combined to constitute a hydrophilic oil-repellent coating film. Among these, silica nanoparticles are particularly preferably used because of versatility, cost, ease of adjustment of average particle diameter, and the like. The hydrophilic oil-repellent coating film is basically composed of nanoparticles and an oil-repellent component described later, but the nanoparticles and the oil-repellent component are not limited as long as the antifouling performance by the hydrophilic oil-repellent coating film is not hindered. Other components may be included. For example, the hydrophilic oil-repellent coating film may contain an antistatic agent in addition to the nanoparticles and the oil-repellent component.

  The diameter of the nanoparticles may be 100 nm or less, but in the present disclosure, it is more preferably in the range of 5 to 100 nm. Moreover, as a more preferable range of the average particle diameter, a range of more than 15 nm and less than 100 nm, or a range of 20 nm to 100 nm can be exemplified.

  When the particle diameter of the nanoparticles is 100 nm or less, it becomes easy to realize a nano-level uneven structure on the surface of the hydrophilic oil-repellent coating film. Further, although depending on the specific configuration of the hydrophilic oil-repellent coating film, if the particle size of the nanoparticles is in the range of 5 to 100 nm, the nano-level uneven structure can be easily adjusted to a more suitable range. be able to. Furthermore, when the hydrophilic oil-repellent coating film contains an adhesive component as described later, the nanoparticle size is set within a range of more than 15 nm and less than 100 nm, or within a range of 20 to 100 nm, It is possible to easily adjust the level uneven structure within a more preferable range.

  The arithmetic average roughness Ra of the surface of the hydrophilic / oil-repellent coating film may be in the range of 2.5 to 100 nm. If the arithmetic average roughness Ra is within this range, it is possible to effectively suppress or prevent at least the adhesion of dry dirt by forming such a hydrophilic oil-repellent coating film on the object to be coated. .

  The oil repellent component contained in the hydrophilic oil repellent coating film according to the present disclosure may be at least one of a fluorine compound and a silicon compound exhibiting oil repellency. The fluorine compound or silicon compound may be a compound containing fluorine or silicon (or both) in the molecule. Examples of these oil repellent components include those used as water and oil repellents, surfactants, surface treatment agents, surface modifiers, antireflection agents, coating agents and the like.

  Specific examples of the oil-repellent component include known organic fluorine compounds or organosilicon compounds, but are not particularly limited. These oil repellent components may be used alone or in combination of two or more. For example, preferred fluorine-based compounds have both a hydrophobic group and a hydrophilic group in the structure, and typical hydrophobic groups include linear or branched perfluoroacrylic groups. Examples thereof include at least one of a sulfonic acid group, a sulfuric acid ester group, and a phosphoric acid ester salt.

  In the hydrophilic oil-repellent coating film according to the present disclosure, the content of the oil-repellent component is not particularly limited, and depending on the purpose of use, hydrophilicity due to nanoparticles and oil-repellency due to the oil-repellent component can be suitably exhibited. The oil repellent component should just be contained in. As a typical preferable content, when the total weight of the hydrophilic oil-repellent coating film is 100% by weight, the oil-repellent component may be contained within the range of 0.1 to 10% by weight. It may be in the range of 1 to 5% by weight or in the range of 0.1 to 4.5% by weight.

  If the content of the oil-repellent component is less than the lower limit of 0.1% by weight, the hydrophilic oil-repellent coating film may not exhibit sufficient oil repellency, depending on various conditions. On the other hand, the upper limit of the oil repellency component is not particularly limited because the content of the oil repellency component may be appropriately adjusted according to the required oil repellency. In addition to being lost, there is a possibility that good surface roughness (fine irregularities) cannot be realized on the surface of the hydrophilic oil-repellent coating film, which may affect the effect of preventing adhesion of dry dirt by the nanoparticles. Depending on the application of the hydrophilic oil-repellent coating film, if the content of the oil-repellent component is 10% by weight or less, preferably 5% by weight or less or less than 5% by weight, fine irregularities derived from nanoparticles are realized. And the realization of oil repellency (oil repellency) by the oil repellency component tend to be compatible with each other.

  The specific shape of the oil-repellent component is not particularly limited as long as the oil-repellent component can be satisfactorily dispersed in the coating film mainly composed of nanoparticles. It is preferable that The oil repellent component is preferably dispersed in the coating film at the molecular level, not in the form of particles, powder or aggregates. The specific molecular weight of the oil-repellent component is not particularly limited, but in general, the average molecular weight may be 10,000 or less, preferably 8000 or less, and more preferably 6000 or less.

  When the molecular weight is used as a standard, it is generally regarded as a polymer when the molecular weight exceeds 10,000. Therefore, the oil-repellent component may be a medium molecule or a low molecule that is not a polymer, depending on the type. preferable. When the oil repellent component is a polymer obtained by polymerizing a monomer component, it may be a polymer having a relatively low degree of polymerization (oligomer). Thus, when the oil repellent component is an oligomer, its molecular weight may exceed 10,000.

  If the oil-repellent component is relatively polymer, or is in the form of particles, powders or aggregates, the surface of the hydrophilic oil-repellent coating film may hinder the formation of fine irregularities by nanoparticles. There is a possibility that the adhesion of dry dirt cannot be effectively suppressed or prevented. For example, when a polymer oil-repellent component or an oil-repellent component such as a particle is interposed between nanoparticles, a good surface roughness may not be realized. Further, when the oil-repellent component is in the form of particles or the like, the surface roughness may be too large depending on the particle size.

  If the oil-repellent component is a relatively low molecule and is not in the form of particles or the like, a composition for forming a coating film is prepared by mixing nanoparticles and the oil-repellent component and applied to the object to be coated. When processed (coated), the oil-repellent component is easily released (easily raised) on the surface of the coating film. Therefore, it becomes easy to impart oil repellency to the surface of the obtained hydrophilic oil-repellent coating film. In addition, when a hydrophilic oil-repellent coating film contains the adhesive component mentioned later, it is preferable that an oil-repellent component has affinity with an adhesive component. Therefore, as the oil repellent component, a compound having a plurality of types of functional groups having different characteristics in one molecule, such as a surfactant, a surface treatment agent, and a surface modifier, is more preferable.

  As described above, the hydrophilic oil-repellent coating film is composed of at least nanoparticles and an oil-repellent component, and the arithmetic average roughness Ra of the surface only needs to be within the above range, and other specific configurations are not particularly limited. . For example, the film thickness of the hydrophilic oil-repellent coating film is not particularly limited, but generally it may be less than 1 μm (1,000 nm), preferably 500 nm or less, and in the range of 20 to 500 nm. It is more preferable.

  If the film thickness of the hydrophilic oil-repellent coating film is less than 1 μm, that is, nano-level, the film thickness is relatively small (thin), so that the charging property of the hydrophilic oil-repellent coating film can be reduced well and dry dirt can be removed. Adhesion can be satisfactorily suppressed or prevented, and the transparency of the hydrophilic oil-repellent coating film can be improved. Further, although depending on various conditions, when the film thickness is 500 nm or less, it is possible to further reduce the chargeability of the hydrophilic oil-repellent coating film and further improve the transparency. Furthermore, although it depends on various conditions, if the film thickness is in the range of 20 to 500 nm, it is possible to realize improvement in transparency and further reduction in chargeability, and further suppress or prevent adhesion of dry dirt. be able to.

  In particular, if the film thickness is 500 nm or less (or in the range of 20 to 500 nm), the coating object is made of a conductive material such as metal, so that even if the hydrophilic oil-repellent coating film is charged, the coating is performed. Since it can be grounded (grounded) by the conductivity of the object, substantial charging can be avoided. Thereby, the adhesion of dry dirt can be more effectively suppressed or prevented. In addition, when the thickness of the hydrophilic oil-repellent coating film is increased (thick), cracks are likely to occur because the hydrophilic oil-repellent coating film is mainly composed of nanoparticles. Can be substantially avoided.

The surface characteristics of the hydrophilic oil-repellent coating film are not particularly limited, but the surface resistivity may be 10 ¹³ Ω / □ or less. Thereby, the chargeability of the hydrophilic oil-repellent coating film can be reduced satisfactorily, so that the adhesion of dry dirt can be satisfactorily suppressed or prevented. Further, the water contact angle of the hydrophilic oil-repellent coating film may be less than 15 °, and may be 5 ° or less depending on various conditions. Similarly, the oil contact angle of the hydrophilic oil-repellent coating film may be more than 15 °. As described above, when the water contact angle of the hydrophilic oil-repellent coating film is small and the oil contact angle is large, the hydrophilicity and oil repellency of the surface are improved. Therefore, even if dry dirt accumulates on the surface of the hydrophilic oil-repellent coating film, the accumulated dry dirt can be easily removed by washing with water. In addition, since the hydrophilic oil-repellent coating film is oil-repellent, it is difficult for oily dirt to adhere to the wet dirt.

  In addition, the measuring method of the particle diameter of a nanoparticle is not specifically limited, A well-known method (Diffusion method, an inertia method, a sedimentation method, a microscope method, a light-scattering diffraction method etc.) can be used suitably. In the measurement value of the present embodiment, the particle size measured by a known method may be at the nano level. Further, the arithmetic average roughness Ra of the hydrophilic / oil-repellent coating film may be measured (evaluated) based on JIS B0601.

  Furthermore, the method for measuring the film thickness of the hydrophilic / oil-repellent coating film is not particularly limited, but in this embodiment, as described in the examples described later, a coating cross section is observed with an electron microscope, and a plurality of observation images are used. The average value of the measured film thickness is calculated. Also, the method for measuring (evaluating) the water contact angle and the oil contact angle of the hydrophilic oil-repellent coating film is not particularly limited. For example, a contact angle meter manufactured by Kyowa Interface Science Co., Ltd., product name: DMo-501 is used. What is necessary is just to measure (evaluate).

  The specific formation method (manufacturing method) of the hydrophilic / oil-repellent coating film is not particularly limited, and various known methods can be used as long as fine irregularities can be formed by nanoparticles. As a typical forming method, a known coating method in which a coating liquid (coating agent) containing nanoparticles is prepared and applied, a sol-gel method, nanoimprinting, transfer using an anodizing mold, sandblasting, Examples include self-organization of ceramics.

  The hydrophilic oil-repellent coating film only needs to be composed of nanoparticles and an oil-repellent component as described above, and further contains an adhesive component composed of at least a material having affinity with the nanoparticles. Also good. The function of the adhesive component is not limited as long as it has a function of adhering nanoparticles to each other and a function of adhering the nanoparticles to the surface of the heat exchanger that is the object to be coated. Therefore, it is sufficient that a material having at least affinity for nanoparticles is a main component.

  When the hydrophilic oil-repellent coating film contains an adhesive component, the strength or durability of the hydrophilic oil-repellent coating film composed of nanoparticles can be improved. In addition, since the nanoparticles are well maintained on the surface of the hydrophilic and oil-repellent coating film, fine irregularities on the surface are easily maintained, and the effect of suppressing or preventing the adhesion of dry dirt can be improved. .

  The specific composition of the adhesive component is not particularly limited as long as it has affinity for the nanoparticles. For example, if the nanoparticles are silica nanoparticles, a material having an affinity for silica can be used as an adhesive component. Examples of materials having an affinity for silica include silane compounds such as tetramethoxysilane or tetraethoxysilane, acrylic resins, and fluororesins. In addition to these materials, the adhesive component may contain known additives. Therefore, the hydrophilic oil-repellent coating film according to the present disclosure only needs to be composed of at least nanoparticles and an oil-repellent component, but may be configured to contain an adhesive component in addition to the nanoparticles and the oil-repellent component. In addition to the nanoparticles, the oil-repellent component, and the adhesive component, a known additive may be included.

  When the hydrophilic oil-repellent coating film contains an adhesive component, the content (content ratio) is not particularly limited. For example, when the total weight of the hydrophilic oil-repellent coating film is 100% by weight, Within the range of 5 to 60% by weight, a more preferable range is within the range of 10 to 50% by weight. Although depending on various conditions, if the adhesive component exceeds 60% by weight, the amount of the adhesive component relative to the nanoparticles becomes excessive, and the arithmetic average roughness Ra of the surface of the hydrophilic oil-repellent coating film is within a predetermined range. May come off. On the other hand, if the adhesive component is less than 5% by weight, effects such as improvement in strength or durability commensurate with the content of the adhesive component may not be obtained sufficiently.

[Dust adhesion rate of hydrophilic oil-repellent coating film]
The hydrophilic oil-repellent coating film according to the present disclosure preferably has a dust adhesion rate of 15% or less. Here, the dust adhesion rate in the present disclosure refers to a coating in which a hydrophilic oil-repellent coating film is formed with respect to the adhesion amount of simulated dust on the surface of the object to be coated (the surface before coating) where the hydrophilic oil-repellent coating film is not formed. It is calculated as the adhesion amount of the simulated dust on the surface of the object (coating surface constituted by a hydrophilic oil-repellent coating film).

  In the present disclosure, mixed simulated dust obtained by mixing organic simulated dust and inorganic simulated dust is preferably used as the simulated dust used for calculating the dust adhesion rate. Specific types of the organic simulated dust and the inorganic simulated dust are not particularly limited, but test powders defined by various standards such as JIS (Japanese Industrial Standard) can be suitably used. In addition, the organic simulated dust and the inorganic simulated dust may be one type, but it is preferable that two or more types are used in combination.

  In the present disclosure, as shown in Examples described later, two types of silica sand are used as inorganic simulated dust, and cotton linter and corn starch are used as organic simulated dust. As specific siliceous sand, two kinds of kind 1 sand and kind 3 sand specified in JIS Z 8901 are used. As the cotton linter, those sold as a kind of test powder by the Japan Air Cleaning Association (JACA) are used. Corn starch is commercially available. Silica sand is used to evaluate the adhesion of inorganic dust, cotton linter is used to evaluate the adhesion of fiber dust out of organic dust, and corn starch is powder dust (dust, It is used to evaluate adhesion of granular dust).

  In the examples and comparative examples of Patent Document 6, the adhesion (antifouling performance) of dust is evaluated using Kanto loam dust or carbon black alone as simulated dust. However, since there are usually a wide variety of dusts that exist in living spaces, as in the present disclosure, when evaluating the antifouling performance of dry dirt, each type of dust is used to adhere. Even if the property (antifouling performance) is evaluated, sufficient evaluation results cannot be obtained. Moreover, Kanto Loam dust is used for the evaluation of hydrophilic dirt, and carbon black is used for the evaluation of lipophilic dirt.

  On the other hand, in the present disclosure, the actual dust existing in the living space is modeled as dry dirt without using a single simulated dust, and a mixture of organic simulated dust and inorganic simulated dust is mixed. Simulated dust is used. Therefore, the antifouling performance of dry dirt can be evaluated well. In addition, powder-type dust that is dry dirt includes those that are hydrophilic, such as Kanto Loam dust. However, in the mixed simulated dust of the present disclosure, fiber-sized dust is used as organic simulated dust. In addition to some cotton linters, hydrophilic corn starch is used as powder dust. Corn starch behaves as dry dirt in the dry state, but in the presence of moisture, it can absorb water and act as hydrophilic dirt. By using corn starch having such characteristics as the powdery dust, it is possible to satisfactorily evaluate the antifouling performance against actual dust.

As described above, the dust adhesion rate is the ratio of the mixed simulated dust on the coating surface constituted by the hydrophilic oil-repellent coating film to the adhesion amount of the mixed simulated dust on the surface before coating of the hydrophilic oil-repellent coating film on the object to be coated. It is defined as the ratio of the amount deposited. In the present disclosure, the adhering amount of the mixed simulated dust on the surface before coating or on the coating surface is calculated as an area ratio of the remaining mixed simulated dust calculated by binarizing an image photographed with an optical microscope. In addition, let this area ratio be a dust adhesion area. When the dust adhesion area on the surface before coating is A ₀ and the dust adhesion area on the coating surface is A ₁ , the dust adhesion rate A _R can be calculated by the following equation (1).

  The dust adhesion rate of the hydrophilic oil-repellent coating film is preferably 15% or less, more preferably 10% or less, further preferably 5% or less, and particularly preferably 2% or less. preferable. If the dust adhesion rate is 15% or less, it is possible to determine that sufficient antifouling performance has been obtained because dust adhesion is not noticeable visually.

  When calculating the dust adhesion rate, for example, a hydrophilic oil-repellent coating film is formed on a part of the surface of the object to be coated or a part of the object to be coated. Can be used as In the sample for evaluation, when the surface on which the hydrophilic / oil-repellent coating film is formed is referred to as the “coating surface”, the mixed simulated dust adheres to the coated surface. The sample for evaluation is preferably neutralized.

  Moreover, the method for adhering the mixed simulated dust to the sample for evaluation and the method for removing the adhering mixed simulated dust are not particularly limited, and various methods can be suitably used. For example, in the examples described later, the mixed simulated dust is screened by depositing a predetermined amount of the mixed simulated dust on the coating surface and then dropping the evaluation sample by tilting it vertically. Moreover, it is not specifically limited about the imaging | photography of the coating | coated surface by an optical microscope, What is necessary is just to image | photograph a several image by the magnification which can observe mixed simulation dust. The binarization processing of the captured image is not particularly limited, and known image processing software or the like may be used.

[Anti-fouling coating]
The antifouling covering according to the present disclosure may be any one that is formed by covering the surface to be antifouling in the covering object with the above-described hydrophilic oil-repellent coating film. As described above, the hydrophilic oil-repellent coating film has irregularities within the range of arithmetic mean roughness Ra of 2.5 to 100 nm on its surface, and contains hydrophilic nanoparticles and an oil-repellent component. It has hydrophilic oil repellency. As a result, it is possible to achieve good hydrophilic oil repellency, to effectively suppress or prevent the adhesion of dry dirt, and to realize self-cleaning properties that make it easy to remove even if dirt adheres. It becomes.

  In the present disclosure, the self-cleaning property (self-cleaning function) can be defined as easily removing dirt by washing with water. As a result of intensive studies by the present inventors, in order to achieve good self-cleaning properties, it is better to examine the dirt adhering to the article based on both the “wet” and “dry” aspects. It became clear.

  Patent Documents 1 to 5 described above only disclose forming a film having hydrophilic oil repellency (hydrophilic oil repellent film) using a fluorine-containing compound. In other words, Patent Documents 1 to 5 focus on “wet” dirt using a “liquid” such as water or oil as a medium (solvent or dispersion medium), and no disclosure is made regarding “dry” dirt. There is no suggestion.

  For example, Patent Document 1 merely evaluates the adhesion of oleic acid or oil-based ink in Examples, and does not evaluate “dryness” stains. Moreover, in patent documents 2-5, since a polymer (resin) is contained in the hydrophilic oil-repellent film | membrane, there exists a possibility of being easy to be charged. In this case, “dry” dirt is likely to adhere to the hydrophilic oil-repellent film due to charging. In addition, none of these Patent Documents 2 to 5 considers whether or not the attached “dry” dirt can be easily removed.

  Further, in Patent Document 6 described above, stains adhering to an article are examined as hydrophilic stains (wet stains) and lipophilic stains (oily stains), and clearly focus on “wet” stains. doing. Moreover, in Patent Document 6, sand dust or dust is regarded as hydrophilic dirt, but these dirt also have an aspect of “dry” dirt. In Examples of Patent Document 6, as described above, Kanto Loam dust and carbon black are cited as specific examples of sand dust or dust, and these are sprayed onto the coating film with air to evaluate adhesion. There is no examination as to whether or not the “dry” dirt can be easily removed.

  In the present disclosure, for example, as shown in Examples described later, the sample of the antifouling coating is immersed in water and allowed to stand, and then the self-cleaning property is evaluated by pulling up the sample. That is, in the antifouling covering according to the present disclosure, it is possible to easily remove “wet” dirt and “dry” dirt even with such simple washing with water.

  Therefore, for example, if the antifouling covering according to the present disclosure is present outdoors, it is possible to remove the dirt by simple water washing such as rainfall or water spraying. In addition, if the antifouling covering according to the present disclosure is a device or a part thereof installed indoors, the antifouling covering may be sprayed or submerged in water without using a special detergent or the like. It is possible to easily remove dirt simply by soaking.

  The specific type or the specific configuration of the antifouling coating according to the present disclosure is not particularly limited, and the article to be imparted with the antifouling performance is used as a coating object, and the above-described hydrophilic oil-repellent coating film is coated. Good. As a typical covering object, an electric product or a part thereof can be cited. By forming a hydrophilic oil-repellent coating film on an electrical product or its parts, dirt is less likely to adhere to the electrical product, and the frequency of cleaning can be reduced. Moreover, if it is an electric product installed in the specific place, the oil stain | pollution | contamination which cannot prevent adhesion with an unevenness | corrugation can be easily removed by self-cleaning.

  Specific electric products include, for example, home appliances that generate wind during use, such as air conditioners (air conditioners), fans, vacuum cleaners, air cleaners, ventilation fans, and dryers; TVs, refrigerators, microwave ovens, etc. Home appliances that are installed and used in specific places, such as shavers or cooking appliances (juicers, mixers, food processors, etc.), etc. Business electric appliances such as commercial fans, commercial vacuum cleaners, commercial ventilation fans, vending machines, refrigerated or refrigerated showcases, and other cold chain devices.

  In the case of electrical products that generate wind, dust accumulates in the wind generation mechanism and easily adheres as dry dirt.Therefore, by forming the hydrophilic oil-repellent coating film according to the present disclosure, the wind generation mechanism is dry. It is possible to effectively suppress the adhesion of dirt.

  For example, if the electrical product that generates wind is an air conditioner, dust is likely to accumulate in heat exchangers, louvers, crossflow fans, etc., but by forming a hydrophilic oil-repellent coating film on these parts, dry dirt Can be effectively prevented. In other words, the antifouling covering according to the present disclosure includes not only a completed electric product called an air conditioner but also parts of an electric product such as a heat exchanger, a louver, and a cross flow fan that constitute the air conditioner.

  Alternatively, when an electrical product that generates wind is provided in a kitchen, for example, in the case of a ventilation fan or an air conditioner provided in a kitchen, not only dry dirt such as dust, but also oil dirt, that is, wet dirt due to cooking or the like adheres. It becomes easy. With the hydrophilic oil-repellent coating film according to the present disclosure, it is possible to make it difficult for dry and wet dirt to adhere, and even if these dirt adheres, the self-cleaning property removes the dirt by simple water washing. be able to. Needless to say, the parts as the antifouling covering are not limited to the heat exchanger of the air conditioner or the parts of the ventilation fan because they differ depending on the type and structure of the electrical product.

  Thus, according to the present disclosure, the hydrophilic oil-repellent coating film is composed of at least hydrophilic nanoparticles having an average particle diameter of 100 nm or less, and the arithmetic average roughness is formed on the surface of the hydrophilic oil-repellent coating film. Ra has irregularities in the range of 2.5 to 100 nm, and further contains at least one of a fluorine compound and a silicon compound as an oil repellent component, a water contact angle of less than 15 °, and an oil contact angle Is more than 15 °. Thereby, the coating film which has the unevenness | corrugation in the said range on the surface is formed using the hydrophilic nanoparticle and the oil-repellent component. Therefore, this hydrophilic and oil-repellent coating film can realize good hydrophilic and oil-repellent properties, and can effectively suppress or prevent the adhesion of dry dirt. It is also possible to realize self-cleaning properties that facilitate removal.

  The present invention will be described more specifically based on examples, comparative examples, and reference examples, but the present invention is not limited thereto. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention.

(Mixed simulated dust)
Uses 1 and 3 types of silica sand as defined in JIS Z 8901, cotton linter sold as a test powder by the Japan Air Cleaners Association (JACA), and commercially available corn starch as simulated dust. These were weighed so as to have an equal weight and mixed thoroughly to obtain mixed simulated dust.

(Arithmetic mean roughness Ra of hydrophilic oil-repellent coating film)
The arithmetic average roughness Ra was measured using a scanning probe microscope (manufactured by Hitachi High-Tech Science Co., Ltd., product name: AFM5300), and calculated based on JIS B0601.

(Evaluation of dust adhesion rate)
After neutralizing the sample for evaluation, the mixed sample powder is sifted over the sample for evaluation, and then the surface of the sample for evaluation is photographed with an optical microscope. The area was measured. Dust on the reference surface when the surface on which the hydrophilic oil-repellent coating film is not formed is used as the reference surface and the surface on which the hydrophilic oil-repellent coating film is formed is used as the evaluation surface. the proportion of dust deposition area on the evaluation surface for adhesion area was dust deposition rate a _R. If dust adhesion area is less than 5% dust deposition rate A _R "◎", if less than 5% 15% "○" was evaluated as "×" if greater than 15%.

(Water contact angle and oil contact angle)
Water or oil (oleic acid) was dropped on the surface of the sample for evaluation, and the contact angle was measured using a contact angle meter manufactured by Kyowa Interface Science Co., Ltd., product name: DMo-501.

(Evaluation of self-cleaning properties)
50 μL of oleic acid was dropped onto the surface of the sample for evaluation and allowed to stand until the diameter expanded to about 10 mm. Then, in a state where the sample for evaluation was held vertically, the sample was immersed in a water tank in which ion-exchanged water was stored and left for 10 seconds. Thereafter, the sample for evaluation was pulled up at a speed of about 5 cm / second, the diameter of oleic acid remaining on the surface was measured in units of 1 mm, and the self-cleaning property _CS was evaluated based on the size of the diameter. The diameter of the oleic acid was evaluated as long 1mm or less self-cleaning property C _S as "◎", if 1mm ultra 3mm or less "○", if 3mm greater "×".

Example 1
A slide glass is prepared as a base material, and silica particles having an average particle diameter of 20 nm are sufficiently dispersed in ethanol as a dispersion medium by adjusting pH, etc., and a sulfonic acid group as a hydrophilic group and a perfluoroalkyl group as a hydrophobic group A coating liquid containing an anionic fluorine compound having a concentration of 3% by weight was prepared by a known method, and the coating liquid was applied to about half of the surface of the substrate and dried. A sample for evaluation in which a hydrophilic oil-repellent coating film of 1 was formed was produced. In this evaluation sample, a hydrophilic oil-repellent coating film is formed on half of the surface, and a hydrophilic oil-repellent coating film is not formed on the other half.

Table 1 shows the results of the arithmetic average roughness Ra, the dust adhesion rate A _R , the water contact angle, the oil contact angle, and the self-cleaning property C _S of the surface of the hydrophilic oil-repellent coating film for the obtained sample for evaluation. .

(Comparative Example 1)
A sample for evaluation in which the hydrophilic oil-repellent coating film of Comparative Example 1 was formed was prepared in the same manner as in Example 1 except that silica particles having an average particle diameter of 100 nm were used. Table 1 shows the results of the arithmetic average roughness Ra, the dust adhesion rate A _R , the water contact angle, the oil contact angle, and the self-cleaning property C _S of the surface of the hydrophilic oil-repellent coating film for the obtained sample for evaluation. .

(Comparative Example 2)
An evaluation sample on which the hydrophilic oil-repellent coating film of Comparative Example 2 was formed was produced in the same manner as in Example 1 except that the concentration of the fluorine compound was changed to 10% by weight. Table 1 shows the results of the arithmetic average roughness Ra, the dust adhesion rate A _R , the water contact angle, the oil contact angle, and the self-cleaning property C _S of the surface of the hydrophilic oil-repellent coating film for the obtained sample for evaluation. .

(Comparative Example 3)
A sample for evaluation in which the hydrophilic oil-repellent coating film of Comparative Example 3 was formed was prepared in the same manner as in Example 1 except that silica particles having an average particle diameter of 250 nm were used. Table 1 shows the results of the arithmetic average roughness Ra, the dust adhesion rate A _R , the water contact angle, the oil contact angle, and the self-cleaning property C _S of the surface of the hydrophilic oil-repellent coating film for the obtained sample for evaluation. .

(Contrast of Examples and Comparative Examples)
As is clear from the results of Example 1, the hydrophilic oil-repellent coating film is composed of nanoparticles of 100 nm or less, and has an unevenness on the surface with an arithmetic average roughness Ra in the range of 2.5 to 100 nm. If it contains a fluorine compound as an oil repellent component, and the water contact angle is less than 15 ° and the oil contact angle exceeds 15 °, the dust adhesion rate can be suppressed to 15% or less, And it turns out that favorable self-cleaning property is realizable.

  On the other hand, as in Comparative Example 2, when the average particle size of the nanoparticles exceeded 100 nm and the arithmetic average roughness Ra exceeded 100 nm, the dust adhesion rate exceeded 15%. Further, as in Comparative Example 1 or 3, even if the average particle diameter and the calculated average roughness Ra of the nanoparticles are within a predetermined range, sufficient self-self is not required unless the water contact angle and oil contact angle are within the predetermined range. Cleanability was not obtained. Therefore, it can be seen that sufficient self-cleaning properties cannot be realized unless the average particle diameter of the nanoparticles, the arithmetic average roughness Ra, the water contact angle, and the oil contact angle on the surface are within predetermined ranges.

  It should be noted that the present invention is not limited to the description of the above-described embodiment, and various modifications are possible within the scope shown in the scope of the claims, and are disclosed in different embodiments and a plurality of modifications. Embodiments obtained by appropriately combining the technical means are also included in the technical scope of the present invention.

  The present invention can be widely and suitably used in the field of suppressing or preventing at least adhesion of dry dirt.

Claims (10)

A coating film composed of at least hydrophilic nanoparticles having an average particle size of 100 nm or less,
The surface of the coating film has irregularities with an arithmetic average roughness Ra in the range of 2.5 to 100 nm, and further contains at least one of a fluorine compound and a silicon compound as an oil repellent component,
The water contact angle is less than 15 ° and the oil contact angle is more than 15 °,
Hydrophilic oil repellent coating film. The average particle diameter of the nanoparticles is in the range of 5 to 100 nm,
The hydrophilic oil-repellent coating film according to claim 1. The nanoparticles are at least one selected from the group consisting of metal nanoparticles, inorganic oxide nanoparticles, inorganic nitride nanoparticles, inorganic chalcogenide nanoparticles, and (meth) acrylic resin nanoparticles. And
The hydrophilic oil-repellent coating film according to claim 1 or 2. The film thickness is 500 nm or less,
The hydrophilic oil-repellent coating film according to any one of claims 1 to 3. The oil-repellent component has an average molecular weight of 10,000 or less and is not formed into particles.
The hydrophilic oil-repellent coating film according to any one of claims 1 to 4. When the total weight is 100% by weight, the oil repellent component is contained within a range of 0.1 to 10% by weight,
The hydrophilic oil-repellent coating film according to any one of claims 1 to 5. In addition to the nanoparticles and the oil-repellent component, it contains an adhesive component composed at least of a material having affinity with the nanoparticles,
The hydrophilic oil-repellent coating film according to any one of claims 1 to 6. The surface resistivity is 10 ¹³ Ω / □ or less,
The hydrophilic oil-repellent coating film according to any one of claims 1 to 7. The surface to be antifouling in the covering object is covered with the hydrophilic oil-repellent coating film according to any one of claims 1 to 8,
Antifouling covering. The covering object is an electric product or a part thereof,
The antifouling covering according to claim 9.