JP7728065B2 - Water-repellent, fluorine-containing, semi-transparent cured film - Google Patents

Description

The present invention relates to a novel water-repellent, fluorine-containing, translucent cured film.

Various water-repellent coating agents are used to impart water-repellent properties to the surfaces of various materials, including electronic materials, medical materials, packaging materials, building materials, and clothing. Many known water-repellent coating agents include compositions containing fluororesins or fluorine compounds. Among these, a technology has been proposed that imparts irregularities to the surface of the coating film formed to achieve even greater water-repellent properties.

For example, a water-repellent coating composition is known that contains a resin solution containing a first fluororesin that can be solidified by drying, and a particle component of a second fluororesin (Patent Document 1).

For example, a cured film with an uneven surface has been proposed, which is formed using a curable composition containing a compound having a perfluoropolyether group and a curable moiety, and a curable resin and/or a curable monomer, and further using a mold with an uneven structure (Patent Document 2).

Japanese Patent Application Laid-Open No. 2016-216585 Japanese Patent Application Laid-Open No. 2019-2014

However, the method described in Patent Document 1 does not provide sufficient durability for the coating film, and when the surface is repeatedly rubbed, the bonding strength between the fine particles and between the fine particles and the resin matrix is weak, which can cause the fine particles to peel off, resulting in a loss of the surface's uneven structure over time and a decrease in water repellency.

Furthermore, because the method of Patent Document 1 uses white micro-sized PTFE resin particles, even if a transparent PET film or the like is used as the base film, the film becomes opaque, limiting the designs that can be used.

Furthermore, the method of Patent Document 2 requires the use of a mold to create the irregularities, and without such equipment, it is impossible to form a cured film with high water repellency. Moreover, because the irregularities are caused by the cured film itself, there is also the risk that the irregularities will reduce or disappear over time due to wear. On the other hand, if the required irregularities are not formed in such a cured film, high water repellency (particularly a contact angle with water of 150 degrees or more) cannot be achieved.

Thus, there is a need for the development of technology that can more reliably maintain high water repellency, but at present such development has not yet been achieved.

Therefore, the main object of the present invention is to provide a cured film that combines high water repellency and durability, and also has transparency.

As a result of extensive research into the problems of the prior art, the inventors discovered that the above objectives could be achieved by employing a composition that can provide a coating film with a specific structure, leading to the completion of the present invention.

That is, the present invention relates to the following water-repellent fluorine-containing translucent cured film.
1. A water-repellent, fluorine-containing, translucent cured film, characterized in that the cured film is made of a curable composition containing a fluorine-containing polymerizable compound and a fluorine-free polymerizable compound and contains inorganic oxide fine particles having a particle size of 200 nm or less.
2. The water-repellent fluorine-containing translucent cured film according to item 1, wherein the arithmetic mean roughness (R _a ) determined by measuring the surface of the cured film using a surface roughness measuring device (Handysurf) is from 0.05 μm to 1.00 μm, the maximum height roughness (R _z ) is from 0.50 μm to 10.00 μm, and the mean element length (R _sm ) is from 50.0 μm to 1000.0 μm.
3. The water-repellent fluorine-containing translucent cured film according to item 1 or 2, wherein the arithmetic mean surface height (S _a ) within a 555.8 μm × 555.8 μm square plane determined by observation of the cured film surface with a white light interference microscope is from 0.01 μm to 2.00 μm, the root mean square height (S _q ) is from 0.05 μm to 3.00 μm, and the maximum cross-sectional height (S _t ) is from 1.00 μm to 30.00 μm.
4. The water-repellent, fluorine-containing, translucent cured film according to any one of items 1 to 3, wherein the fluorine concentration at the surface of the cured film as determined by XPS analysis is 5 to 50 atomic %.
5. The water-repellent, fluorine-containing translucent cured film according to any one of items 1 to 4, wherein the fluorine-containing polymerizable compound is perfluoropolyether (meth)acrylate.
6. The water-repellent, fluorine-containing translucent cured film according to any one of items 1 to 5, wherein the fluorine-free polymerizable compound is a fluorine-free (meth)acrylate compound.
7. The water-repellent, fluorine-containing translucent cured film according to any one of items 1 to 6, wherein the surfaces of the inorganic oxide fine particles are modified with (meth)acryloyl groups.
8. The water-repellent fluorine-containing translucent cured film according to any one of items 1 to 7, wherein the content of the inorganic oxide fine particles is 1 to 200 parts by weight per 100 parts by weight of the total of all components of the curable composition excluding the inorganic oxide fine particles.
9. The water-repellent, fluorine-containing translucent cured film according to any one of items 1 to 8, which has a transmittance (L ^* value) of 60 or more as measured in a transmittance measurement mode with a spectrophotometer (CM-5).

The main object of the present invention is to provide a cured film that combines high water repellency and durability while also having relatively high transparency. In particular, the present invention makes it possible to provide a cured film with a specified uneven surface by combining a specific curable compound with specific inorganic oxide microparticles and curing them with active energy rays. This makes it possible to impart high water repellency and high abrasion resistance, thereby making it possible to maintain high water repellency for a relatively long period of time. Furthermore, by limiting the size of the inorganic oxide microparticles to 200 nm or less, it is possible to provide a cured film with relatively high transparency.

The cured film of the present invention, which has these characteristics, can be widely applied to various materials or products whose surfaces require water repellency.

FIG. 2 is a view showing the results of observing a cross section of the cured film obtained in Example 1 with a field emission scanning electron microscope.

1. Water-repellent fluorine-containing semi-transparent cured film The water-repellent fluorine-containing semi-transparent cured film of the present invention (cured film of the present invention) is characterized in that inorganic oxide fine particles having a particle size of 200 nm or less are contained in a cured film of a curable composition containing a fluorine-containing polymerizable compound and a fluorine-free polymerizable compound.

Details about the types and compositions of the components (e.g., fluorine-containing polymerizable compounds) that make up the cured film of the present invention will be explained below in "2. Method for producing cured film."

The cured film of the present invention is composed of a cured product of a curable composition containing a fluorine-containing polymerizable compound and a fluorine-free polymerizable compound. It has a structure in which inorganic oxide fine particles are dispersed within the matrix, using this cured product as the matrix.

In the cured film of the present invention, at least a portion of the inorganic oxide microparticles contribute to the formation of an uneven surface on the cured film. This allows the surface of the cured film of the present invention to be given a specific uneven shape, resulting in excellent water repellency, durability, and good transparency.

From the viewpoints of such water repellency, durability, and transparency, it is desirable that the uneven shape have an arithmetic mean roughness (R _a ) value of 0.05 μm or more and 1.00 μm or less (particularly 0.10 μm or more and 0.80 μm or less), a maximum height roughness (R z ) of 0.50 μm or more and 10.00 μm or less (particularly 0.60 μm or more and 8.00 μm or less), and a mean element length (R _sm ) of 50.0 μm or more and 1000.0 μm or less (particularly 100.0 μm or more and 800.0 μm or less), as determined by measuring the surface of the cured film using a surface roughness measuring device ( _Handysurf , manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with the ASME 2009 standard.

Furthermore, from a similar viewpoint, it is desirable that the uneven shape has an arithmetic mean surface height (S _a ) within a square surface of 555.8 μm × 555.8 μm squares, determined by observing the surface of the cured film with a white light interference microscope in accordance with ISO Standard 25178, of 0.01 μm or more and 2.00 μm or less (particularly 0.03 μm or more and 1.00 μm or less), a root mean square height (S _q ) of 0.05 μm or more and 3.00 μm or less (particularly 0.06 μm or more and 1.50 μm or less), and a maximum cross-sectional height (S _t ) of 1.00 μm or more and 30.00 μm or less (particularly 2.00 μm or more and 20.00 μm or less).

In order to form the above-described cured film surface and exhibit high transparency, inorganic oxide microparticles with a particle size of 200 nm or less (particularly 150 nm or less) can be used. As long as these conditions are met, nanoparticles with an average primary particle size of 1 to 100 nm (particularly 2 to 50 nm) can also be used.

The shape of the inorganic oxide microparticles is not limited as long as they can form fine irregularities on the surface; for example, any shape, such as spherical, scaly, needle-like, or irregular, can be used.

The content of inorganic oxide fine particles in the cured film of the present invention varies depending on the type of inorganic oxide fine particles used, but from the standpoint of water repellency and durability, the content of inorganic oxide fine particles is generally about 1 to 200 parts by weight, preferably 5 to 150 parts by weight, and more preferably 10 to 100 parts by weight, per 100 parts by weight of the total of the components of the curable composition excluding the inorganic oxide fine particles and the solvent . Therefore, the content of inorganic oxide fine particles in the cured film of the present invention can be, for example, about 0.5 to 70% by weight (particularly about 4 to 60% by weight).

The cured film of the present invention may contain other additives as long as they do not interfere with the effects of the present invention. For example, additives such as colorants (dyes, pigments), antistatic agents, antioxidants, UV absorbers, dispersants, surfactants, leveling agents, surface conditioners, anti-sagging agents, thickeners, antifoaming agents, and lubricants may be contained. Note that if any of these additives fall under the category of inorganic oxide fine particles, they are included in the content of the inorganic oxide fine particles described above.

The cured film of the present invention is formed by curing a fluorine-containing polymerizable compound, etc., as described above. As an indicator of its fluorine content, the fluorine concentration at the surface of the cured film measured by XPS analysis (X-ray photoelectron spectroscopy) is preferably 5 to 50 atomic % (particularly 10 to 40 atomic %). By having a water-repellent fluorine component present at least on the surface of the cured film within this range, excellent water repellency can be more reliably achieved.

The cured film of the present invention is not particularly limited in its transmittance, so long as it is transparent or translucent. The transmittance is measured using a spectrophotometer (CM-5, Konica Minolta Japan Inc.) in the transmittance measurement mode (L ^* value). It also encompasses colorless, transparent, or translucent, colored, transparent, or colored, translucent, etc. When high transparency is required, a transmittance of 60 or more (particularly 65 or more) is preferred. The upper limit of the transmittance can be, for example, 100, but is not limited thereto.

The thickness of the cured film of the present invention can be appropriately set depending on, for example, the material of the substrate to which the cured film of the present invention is applied, the desired water repellency, transmittance, etc., and can be, for example, within the range of approximately 0.1 to 10 μm, but is not limited to this.

2. Method for Producing Water-Repellent Fluorine-Containing Translucent Cured Film The cured film of the present invention can be suitably produced, for example, by a method comprising: (1) a step (coating film-forming step) of forming a coating film from a fluorine-containing composition (the composition of the present invention) containing (a) inorganic oxide fine particles having a particle size of 200 nm or less, (b) a fluorine-containing polymerizable compound, and (c) a fluorine-free polymerizable compound; and (2) a step (curing step) of curing the coating film to obtain a cured film.

The following provides a detailed description of each component that makes up the composition of the present invention. In the present invention, unless otherwise specified, acryloyl groups and methacryloyl groups are collectively referred to as "(meth)acryloyl groups." Acrylates and methacrylates are collectively referred to as "(meth)acrylates."

(1) Coating film formation step In the coating film formation step, a coating film is formed from a fluorine-containing composition (the composition of the present invention) containing (a) inorganic oxide fine particles having a particle size of 200 nm or less, (b) a fluorine-containing polymerizable compound, and (c) a fluorine-free polymerizable compound.

Inorganic oxide fine particles The inorganic oxide fine particles used have a particle size of 200 nm or less. By incorporating such inorganic oxide fine particles into the composition of the present invention, when the composition is formed into a coating film, extremely fine irregularities can be formed on the surface of the coating film, which can contribute to high water repellency.

The type of inorganic oxide is not particularly limited as long as it provides the above-mentioned effects, and examples include inorganic oxides such as silicon oxide, titanium oxide, and aluminum oxide. These inorganic oxides can be used alone or in combination of two or more. As in the above specific example, in the present invention, inorganic oxides also include metal oxides.

These inorganic oxide fine particles themselves may be publicly known or commercially available. Examples of silicon oxide include products under the names "AEROSIL 50", "AEROSIL 150", "AEROSIL 200", "AEROSIL 300", "AEROSIL 380", "AEROSIL R972", "AEROSIL R972V", "AEROSIL R972CF", "AEROSIL R974", "AEROSIL RX200", "AEROSIL RY200", "AEROSIL R202", "AEROSIL R805", "AEROSIL R812", and "AEROSIL R812S" (all manufactured by Nippon Aerosil Co., Ltd.), "YA010C", "YA050C", and "YC100C" (all manufactured by Admattex Co., Ltd.). An example of titanium oxide is a product called "AEROXIDE TiO ₂ T805" (manufactured by Nippon Aerosil Co., Ltd.), etc. An example of aluminum oxide is a product called "AEROXIDE Alu C" (manufactured by Nippon Aerosil Co., Ltd.), etc.

In particular, inorganic oxide microparticles preferably have functional groups on the surface of each particle. For example, polymerizable functional groups (curable functional groups) such as (meth)acryloyl groups, (meth)acryloyloxy groups, epoxy groups, allyl groups, and vinyl groups are preferred. This strengthens the bond between the inorganic oxide microparticles and the resin matrix in the cured film formed by active energy ray curing, resulting in a cured film with superior durability (particularly abrasion resistance). These functional groups can be imparted by surface-treating untreated inorganic oxide microparticles using known methods. For example, the microparticle surfaces can be surface-modified with a silane coupling agent having a reactive functional group, such as a (meth)acryloyl group. Alternatively, commercially available inorganic oxide microparticles with such functional groups pre-imparted can be used. Examples include products with the names "AEROSIL R711" and "AEROSIL VP RM50L" (both manufactured by Nippon Aerosil Co., Ltd.).

As mentioned above, inorganic oxide microparticles with a particle size of 200 nm or less can be used. For example, nanoparticles with an average primary particle size of 1 to 100 nm (particularly 2 to 50 nm) can also be used.

The composition of the present invention may contain trace amounts of particles exceeding 200 nm in diameter, as long as the effects of the present invention are not impaired. However, it is preferable to remove particles exceeding 200 nm in diameter by classification or other means.

In the present invention, the average primary particle size can be measured using a field emission scanning electron microscope (FE-SEM). If the resolution of the scanning electron microscope is low, it may be measured using another electron microscope, such as a transmission electron microscope. Specifically, if the particle shape is spherical, the diameter is considered to be the diameter, and if the particle shape is non-spherical, the longest diameter is considered to be the diameter. The average value of the diameters of 300 particles randomly selected by observation using a scanning electron microscope or the like is taken to be the average primary particle size.

The content (solids ratio) of inorganic oxide particles in the composition of the present invention is not limited, but can be appropriately set within the range of 1 to 200 parts by weight (particularly 5 to 150 parts by weight) per 100 parts by weight of the total components of the composition of the present invention excluding inorganic oxide particles and solvent (hereinafter also referred to as the "polymerizable mixture"). Therefore, the content of inorganic oxide particles in the composition of the present invention can be, for example, approximately 1 to 60% by weight (particularly approximately 4 to 60% by weight).

The total of all components of the composition of the present invention excluding inorganic oxide fine particles and solvent usually refers to the total (solids content) of the fluorine-containing polymerizable compound, the fluorine-free polymerizable compound, and the photopolymerization initiator.

One preferred embodiment of the present invention involves the use of two or more inorganic oxide microparticles with different average primary particle diameters within the particle size range described above. For example, one embodiment uses first microparticles and second microparticles with a larger average primary particle diameter than the first microparticles. In this case, the average primary particle diameter of the first microparticles is typically preferably 1 nm to 20 nm, and more preferably 5 nm to 15 nm. The average primary particle diameter of the second microparticles is typically preferably 21 nm to 100 nm, and more preferably 25 nm to 50 nm. By using these two types of microparticles with different sizes, a nanoscale uneven structure that contributes to water repellency and a microscale uneven structure (surface unevenness) that contributes to durability are more reliably formed when the cured film is formed, thereby further improving water repellency and durability.

In this case, the content of the first microparticles is preferably from 1 to 50 parts by weight, and more preferably from 10 to 40 parts by weight, relative to 100 parts by weight of the polymerizable mixture. The content of the second microparticles is preferably from 1 to 100 parts by weight, and more preferably from 10 to 50 parts by weight, relative to 100 parts by weight of the polymerizable mixture. If the first microparticles and second microparticles are within these ranges, the water repellency and durability will be even better.

The materials of the first and second microparticles are not particularly limited and may be the same or different materials.

Fluorine-Containing Polymerizable Compound The fluorine-containing polymerizable compound is a basic component for imparting water repellency to the cured film formed from the composition of the present invention.

The fluorine-containing polymerizable compound is not particularly limited as long as it has a fluorine-containing organic group and a polymerizable (curable) functional group (polymerizable double bond). Fluorine-containing polymerizable compounds include not only compounds used as monomers before polymerization, but also compounds with relatively large molecular weights, generally known as oligomers or macromonomers.

Examples of such fluorine-containing organic groups include a) organic groups having a perfluoroalkyl structure, b) organic groups having a perfluoropolyether structure, and c) alkylene groups in which some of the hydrogen atoms have been substituted with fluorine atoms. Among these, organic groups having a perfluoropolyether structure are preferred.

The perfluoropolyether structure is an organic group consisting of one or more repeating units of -[C _n F _2n O]- (where n is an integer of 1 or more). These may be either linear or branched. Therefore, for example,
-CF ₂ -,
-CF( _CF3 )-,
-CF ₂ CF ₂ -,
-CF ₂ CF ₂ CF ₂ -,
-CF( _CF3 ) _CF2-
-CF( _{CF3 ) CF2CF2-}
-CF( _CF3 )CF( _CF3 ) _CF2-
These include, but are not limited to:

When the repeating unit is composed of two or more, the respective —[C _n F _2n O]— groups may be the same as or different from each other.

The polymerizable functional group bonded to the fluorine-containing organic group is not limited, but particularly preferred are (meth)acryloyl groups, (meth)acryloyloxy groups, epoxy groups, allyl groups, vinyl groups, etc. The fluorine-containing polymerizable compound may contain one or more polymerizable functional groups.

The polymerizable functional group may be bonded to either the end or side chain of the fluorine-containing organic group.

Furthermore, the polymerizable functional group may be bonded directly to the fluorine-containing organic group, or may be bonded via another organic group (such as a divalent organic group). Therefore, for example, the polymerizable functional group may be bonded to the fluorine-containing organic group via a urethane bond -COONH- or an ester bond -COO-. Therefore, for example, perfluoropolyether urethane (meth)acrylate, which has a structure in which a (meth)acryloyl group is bonded to a perfluoropolyether group via a urethane bond, can also be used as the fluorine-containing polymerizable compound.

The molecular weight of the fluorine-containing polymerizable compound may be within the range of approximately 100 to 100,000 in number average molecular weight, but is not limited to this. Therefore, for example, compounds with a number average molecular weight of approximately 500 to 20,000 can also be used.

Specific examples of fluorine-containing polymerizable compounds include at least one of perfluoroalkyl (meth)acrylate, perfluoroalkyl vinyl ether, perfluoropolyether (meth)acrylate (particularly perfluoropolyether urethane (meth)acrylate), 1H,1H,2H,2H-tridecafluorooctyl acrylate, etc. Among these, perfluoropolyether (meth)acrylate (particularly perfluoropolyether urethane (meth)acrylate) is preferred. These compounds contain highly reactive (meth)acryloyl groups as well as perfluoropolyether groups that provide excellent water and oil repellency and droplet removal properties, making it possible to more reliably form cured films with higher water repellency. These compounds can be used alone or in combination.

In the present invention, the fluorine-containing polymerizable compound itself can be a known or commercially available product. Examples of the perfluoropolyether urethane (meth)acrylate include the product names "Fluorolink AD1700" and "Fluorolink MD700" (both manufactured by Solvay Specialty Polymers Japan Ltd.), and the 1H,1H,2H,2H-tridecafluorooctyl acrylate includes the product name "Viscoat 13F" (manufactured by Osaka Organic Chemical Industry Ltd.).

The amount of fluorine-containing polymerizable compound is not limited, but is preferably 5 to 95 parts by weight, and more preferably 30 to 60 parts by weight, per 100 parts by weight of the polymerizable mixture. If the amount of fluorine-containing polymerizable compound is 5 parts by weight or more, the water repellency of the cured film will be higher, and if it is 95 parts by weight or less, polymerization initiators and the like can be added appropriately, making curing easier and more reliable.

Fluorine-Free Polymerizable Compound The fluorine-free polymerizable compound is a polymerizable compound that does not contain fluorine, and has the effect of more reliably reducing the viscosity of the composition of the present invention when a perfluoropolyether acrylate or the like having a relatively high viscosity is used.

The type of fluorine-free polymerizable compound is not particularly limited, as long as it has one or more polymerizable functional groups (curable functional groups) such as a (meth)acryloyl group, (meth)acryloyloxy group, epoxy group, allyl group, or vinyl group, and does not contain fluorine. The compound can be modified depending on the additional performance required for the application, such as adhesion to the substrate, chemical resistance, flexibility, and weather resistance. Examples include 1,6-hexanediol diacrylate (HDDA), tetrahydrofurfuryl acrylate (THFA), and amine (meth)acrylate. These compounds can be used alone or in combination.

The content of the non-fluorine-containing polymerizable compound is not limited, but it is preferably set to 5 to 90 parts by weight per 100 parts by weight of the polymerizable mixture.

In addition, in the composition of the present invention, the amine (meth)acrylate plays a role in effectively suppressing curing inhibition on the surface. From this perspective, it is preferable that the amine (meth)acrylate be contained in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the polymerizable mixture.

Other Additives In the composition of the present invention, particularly when ultraviolet light is used as the active energy ray, a photopolymerization initiator can also be used. The photopolymerization initiator is not particularly limited as long as it can cause polymerization upon ultraviolet irradiation. Therefore, any type of photopolymerization initiator, such as a cleavage-type polymerization initiator or a hydrogen abstraction-type polymerization initiator, can be used. For example, intramolecular cleavage-type initiators include alkylphenones and oxime esters. Hydrogen abstraction-type initiators include benzophenone/amines and thioxanthone/amines. These can be used alone or in combination of two or more. These photopolymerization initiators themselves can be known or commercially available. For example, the product name "Omnirad 127" (manufactured by IGM Resins B.V.) can be used.

The amount of photopolymerization initiator used is not particularly limited, but is typically about 0.1 to 10 parts by weight per 100 parts by weight of the total of the fluorine-containing polymerizable compound and the fluorine-free polymerizable compound.

A solvent can be used in the composition of the present invention, if necessary, for purposes such as viscosity adjustment. The solvent is not particularly limited, and examples include organic solvents such as aromatic hydrocarbons such as toluene and xylene, alicyclic hydrocarbon solvents such as methylcyclohexane and cyclohexane, ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as methyl ethyl ketone and acetone, and alcohol solvents such as isopropyl alcohol and denatured ethanol. These can be used alone or in combination of two or more.

When a solvent is used, the amount used is not particularly limited, but can be adjusted appropriately to achieve an appropriate viscosity depending on the coating/painting method, etc., within the range of approximately 10 to 500 parts by weight per 100 parts by weight of the total amount of inorganic oxide microparticles and polymerizable mixture, but is not limited to this amount.

The composition of the present invention may contain additives such as colorants (dyes, pigments), antistatic agents, antioxidants, UV absorbers, dispersants, surfactants, leveling agents, surface conditioners, anti-sagging agents, thickeners, antifoaming agents, and lubricants, as long as the effects of the present invention are not impaired. Note that if any of these additives also fall under the category of inorganic oxide microparticles, they will be included in the content of the inorganic oxide microparticles described above.

The composition of the present invention can be prepared by uniformly mixing these components. For mixing, a known or commercially available kneader, mixer, etc. can be used.

In the coating film formation process, a coating film is formed using the composition of the present invention as described above. Typically, a coating film of the composition of the present invention is formed on a substrate.

The substrate used in the coating film formation process can be a material to be imparted with water repellency, or a cured film formed on that material's surface. Here, water repellency includes not only the ability to repel water, but also the ability to repel ice, ice water, etc. Therefore, the composition of the present invention can also be used to prevent water adhesion or the accumulation of ice, snow, etc.

The material of the substrate is not particularly limited, and may be, for example, synthetic resin, rubber, metal, ceramic, fibrous material (paper, nonwoven fabric, woven fabric, etc.), composite materials of these, etc. Furthermore, the substrate may be a finished product (finished product), a semi-finished product, or the raw material thereof. More specifically, the substrate can be widely used for such products as packaging materials, daily necessities, building materials, clothing, cosmetics, pharmaceuticals, etc. Furthermore, the substrate can be used for products used outdoors for waterproofing, preventing ice and snow accumulation, etc. (building materials, automobile parts, etc.), or materials for such products.

A coating film can be formed, for example, by applying the liquid composition of the present invention to a substrate. The application method is not particularly limited, and can be carried out using, for example, a doctor blade, bar coater, brush, roller, or spray gun. Furthermore, in the present invention, the above-described application and drying process can be repeated two or more times to achieve a desired coating thickness.

The thickness of the coating film can be set appropriately depending on, for example, the intended use of the cured film. For example, the thickness of the cured film can be adjusted to approximately 0.1 to 10 μm, but is not limited to this.

After the coating film is formed, it is preferable to heat treat it as needed to dry it. The degree of heat treatment varies depending on the amount of coating applied in the previous process and the amount of solvent contained in the composition, but it is possible to determine whether the solvent has completely evaporated by visual inspection, smell, etc. If the heat treatment is insufficient, the coating film may not cure properly in the subsequent curing process. If heat treatment is performed, it may be carried out at a temperature of, for example, about 50 to 160°C, but this is not limiting.

(2) Coating Film Curing Step In the coating film curing step, the coating film formed above is cured to obtain a cured film.

The curing method is not particularly limited as long as it can cure the composition of the present invention by polymerizing it, and examples include curing with active energy rays and heat curing. In the present invention, curing with active energy rays is particularly desirable.

The active energy rays used in the curing process are not limited, and examples include electron beams, ultraviolet rays, far ultraviolet rays, visible light, and infrared rays. These can be irradiated using publicly known or commercially available active energy ray irradiation devices.

The irradiation conditions can also be set within the ranges normally adopted. For example, when ultraviolet light is used as the active energy ray, the ultraviolet irradiation conditions can be a peak irradiance of about 10 to 1,000 mW/ ^cm² and an integrated light quantity of about 100 to 3,000 mJ/ ^cm² . However, this is when an ultraviolet integrated illuminance meter having a light receiver with a wavelength of 365 nm is used.

For example, when using electron beams as the active energy rays, the electron beam irradiation conditions can be an acceleration voltage of 100 to 300 kV and a dose of approximately 10 to 100 kGy.

The following examples and comparative examples will explain the features of the present invention in more detail. However, the scope of the present invention is not limited to these examples. In the examples, "%" refers to "% by weight" unless otherwise specified.

Example 1
A polymerizable mixture was prepared by mixing 50 parts by weight of Fluorolink AD1700 (perfluoropolyether acrylate, solids content 70% by weight, Solvay Specialty Polymers Japan), 15 parts by weight of Viscoat #230 (1,6-hexanediol diacrylate, Osaka Organic Chemical Industry Ltd.), 50 parts by weight of Viscoat #150 (tetrahydrofurfuryl acrylate, Osaka Organic Chemical Industry Ltd.), 4 parts by weight of Omnirad 127 (cleavage-type polymerization initiator, IGM Resins B.V.), 1 part by weight of CN371NS (amine acrylate, SARTOMER), and 1 part by weight of benzophenone (photopolymerization initiator, Fujifilm Wako Pure Chemical Industries, Ltd.).
To 100 parts by weight of the obtained polymerizable mixture, 10 parts by weight of R711 (methacrylic group surface-modified silica fine particles (average primary particle diameter: 12 nm), AEROSIL), 10 parts by weight of VP RM50L (methacrylic group surface-modified silica fine particles (average primary particle diameter: 40 nm), AEROSIL), and 100 parts by weight of ethyl acetate (Fujifilm Wako Pure Chemical Industries) were added and mixed to obtain a mixed solution.
The resulting mixture was applied to a double-sided adhesive PET film (Toyobo Co., Ltd., Cosmoshine, 100 μm thick) using a No. 8 bar coater. After application, the film was dried at 100° C. for 3 minutes to form a coating film on the double-sided adhesive PET film. The coating film was then irradiated with ultraviolet light using a high-pressure mercury UV lamp to form a cured film with a thickness of approximately 1 μm.
The UV irradiation conditions were as follows: the coated film was placed on a conveyor and passed under a UV lamp once. The UV irradiance was a peak irradiance of 200 to 300 mW/ ^cm² , and the cumulative dose of light irradiated was 650 to 800 mJ/ ^cm² . The peak irradiance and cumulative dose were measured using an Eye UV integrating illuminance meter (product name: "UVPF-A1" (equipped with a 365 nm photodetector PD-365), manufactured by Iwasaki Electric Co., Ltd.).

Example 2
A mixed solution was obtained by adding and mixing R711 (20 parts by weight), VP RM50L (20 parts by weight), and ethyl acetate (300 parts by weight) to 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 1. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 3
A mixed solution was obtained by adding R711 (10 parts by weight) and ethyl acetate (100 parts by weight) to 100 parts by weight of a polymerizable mixture prepared in the same manner as in Example 1 and mixing them together. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 4
A mixed solution was obtained by adding R711 (20 parts by weight) and ethyl acetate (150 parts by weight) to 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 1 and mixing them. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 5
A mixed solution was obtained by adding R711 (40 parts by weight) and ethyl acetate (300 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 1. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 6
A mixed solution was obtained by adding VP RM50L (20 parts by weight) and ethyl acetate (100 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 1. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 7
A mixed solution was obtained by adding VP RM50L (40 parts by weight) and ethyl acetate (166 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 1. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 8
A polymerizable mixture was prepared by mixing AD1700 (10 parts by weight), Viscoat #230 (24.2 parts by weight), Viscoat #150 (80.8 parts by weight), Omnirad 127 (4 parts by weight), CN371NS (1 part by weight), and benzophenone (1 part by weight). At this time, the proportion of the fluorine-containing polymerizable compound in the polymerizable mixture was 5.9%.
To 100 parts by weight of the obtained polymerizable mixture, R711 (5 parts by weight), VP RM50L (5 parts by weight), and ethyl acetate (75 parts by weight) were added and mixed to obtain a mixed solution, which was then coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 9
A mixed solution was obtained by adding and mixing R711 (10 parts by weight), VP RM50L (10 parts by weight), and ethyl acetate (100 parts by weight) to 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 8. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 10
To 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 8, R711 (20 parts by weight), VP RM50L (20 parts by weight), and ethyl acetate (300 parts by weight or more) were added and mixed to obtain a mixed solution. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 11
A mixed solution was obtained by adding R711 (10 parts by weight) and ethyl acetate (100 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 8. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 12
A mixed solution was obtained by adding R711 (20 parts by weight) and ethyl acetate (150 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 8. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 13
A mixed solution was obtained by adding VP RM50L (20 parts by weight) and ethyl acetate (100 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 8. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 14
A mixed solution was obtained by adding VP RM50L (40 parts by weight) and ethyl acetate (166 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 8. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 15
A polymerizable mixture was prepared by mixing AD1700 (115 parts by weight), Omnirad 127 (4 parts by weight), CN371NS (1 part by weight) and benzophenone (1 part by weight).
To 100 parts by weight of the obtained polymerizable mixture, R711 (10 parts by weight), VP RM50L (10 parts by weight), and ethyl acetate (125 parts by weight) were added and mixed to obtain a mixed solution, which was then coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 16
A mixed solution was obtained by adding R711 (20 parts by weight) and ethyl acetate (150 parts by weight) to and mixing with 100 parts by weight of the polymerizable mixture prepared in the same manner as in Example 15. The mixed solution obtained was coated, dried, and cured in the same manner as in Example 1 to obtain a cured film.

Example 17
A polymerizable mixture was prepared by mixing Fluorolink AD1700 (50 parts by weight), Viscoat #230 (15 parts by weight), Viscoat #150 (50 parts by weight), and CN371NS (amine acrylate, SARTOMER) (1 part by weight). The proportion of fluorine-containing polymerizable compounds in the polymerizable mixture was 34.7%. The polymerizable mixture of Example 17 was prepared by replacing the polymerizable mixture of Example 1 with the polymerizable mixture without the polymerization initiator. The polymerizable mixture of Example 17 is cured by electron beam irradiation, so no initiator is required.
To 100 parts by weight of the resulting mixture, R711 (10 parts by weight), VP RM50L (10 parts by weight), and ethyl acetate (125 parts by weight) were added and mixed to obtain a mixed liquid.
The resulting mixture was applied to a double-sided adhesive PET (polyethylene terephthalate) film using a No. 8 bar coater. After application, the mixture was dried at 100°C for 3 minutes to form a coating film on the double-sided adhesive PET film. The coating film was then irradiated with electron beams using an electron beam irradiator (CB250, I-Electron Beam Co., Ltd.) to produce a cured film. The electron beam irradiation conditions were an acceleration voltage of 200 kV and an absorbed dose of 30 kGy, with a single irradiation.

Comparative Example 1
A 9 wt% solution of amorphous fluororesin (product name "CYTOP", CTX-809A, manufactured by Asahi Glass Co., Ltd.) was diluted with CT-solve 180 to obtain a 1.0 wt% CYTOP solution. TFW3000F, TFW1000, and TFW500 (polytetrafluoroethylene (PTFE) powders with average primary particle sizes of 3 μm, 10 μm, and 25 μm, respectively, manufactured by Seishin Co., Ltd.) were mixed in a 1:1:1 (weight ratio) ratio to obtain a PTFE mixed powder. The PTFE mixed powder was added to the 1.0 wt% CYTOP solution and stirred to obtain a 6.0 wt% PTFE coating solution. The resulting coating solution was applied to a double-sided adhesive PET film using a No. 24 bar coater, followed by heat curing at 100°C for 1 hour and then at 150°C for 3 hours. It was thought that it would be better to use a No. 8 bar coater (liquid film thickness 18 μm) as in the examples, but the PTFE mixed powder in the coating solution was coarse, and a coating film containing the PTFE powder uniformly could not be formed using the No. 8 bar coater, so a No. 24 bar coater was used.

Comparative Example 2
A coating solution and a PTFE mixed powder were prepared in the same manner as in Comparative Example 1. The coating solution was applied to a double-sided adhesive PET film using a No. 24 bar coater, and then 7 g of the PTFE mixed powder was evenly sprinkled onto a 0.04 m ² (20 cm x 20 cm) coated surface. In other words, the PTFE mixed powder was sprinkled so that the layering amount was 175 g/m ^2. The film was then heat-cured at 100°C for 1 hour, followed by 3 hours at 150°C.

Test Example 1
The treated surface (cured film) of each sample was used as the test surface, and the contact angle of 2.0 μL of pure water was measured using a contact angle measuring device ("DMs-401" manufactured by Kyowa Interface Science Co., Ltd.). The treated surface (cured film) of each sample was used as the test surface, and two paper wipers (Kimwipe S-200 mini manufactured by Nippon Paper Crecia Co., Ltd.) were attached to the bottom of a 50 g weight with a 4 cm square bottom. The weight was placed on the test surface, and the weight was pulled in one direction parallel to the test surface at approximately 20 cm/sec. The contact angle was measured every time the sample was pulled and rubbed. The measurement temperature may be room temperature (e.g., 20°C).
In addition, in Comparative Example 2, after the first friction, significant detachment of the PTFE mixed powder occurred, and it was determined that the paper wiper surface was not in an appropriate friction state for the second friction, so the paper wiper was replaced for the second friction. Although no particle detachment was observed in the Example, the paper wiper was replaced after the first friction in order to match the conditions of the Example and the Comparative Example. After the second and subsequent frictions, no particle detachment was observed, so the paper wiper was not replaced. The number of frictions and the contact angle (unit: degrees) at that time are shown in Tables 2 and 3.

The results in Table 3 show that Comparative Example 1 did not achieve high water repellency. Comparative Example 2 achieved high water repellency before rubbing, but with rubbing, the PTFE mixed powder was significantly detached, and after two rubbings, the contact angle significantly decreased. On the other hand, in the Examples shown in Table 2, after three rubbings, most Examples showed very high water repellency, with contact angles of 140 degrees or more. Even after 10 rubbings, all Examples showed high water repellency, with contact angles of 135 degrees or more. This clearly shows that each Example exhibits higher durability than Comparative Example 2. As described above, it is clear that the present invention can achieve a surface that is both highly durable and highly water repellent.

Test Example 2
The arithmetic mean roughness (R _a ), maximum height roughness (R _z ), and mean element length (R _sm ) were measured using a surface roughness measuring instrument (Handysurf, manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with the ASME 2009 standard. The measurements were performed three times, and the average value was used as the measured value. The measurement conditions were a cutoff value (λ _c ): 0.8 mm, and a reference length (L): 4 mm. The measurement results are shown in Table 4.

Test Example 3
The cured film surface was observed using a white light interference microscope (VS1330, Hitachi High-Tech Corporation) to measure the arithmetic mean surface height (S _a ), root mean square height (S _q ), and maximum cross-sectional height (S _t ) within a 555.8 μm × 555.8 μm square surface in accordance with ISO standard 25178. The measurement conditions were: camera: high pixel count, camera speed: standard, objective lens: 10XDI, lens barrel: 1X, zoom lens: 1X, light source: 530 white, measuring device: piezo, measurement mode: Wave, field of view size: 1024 × 1024, scan range: start: 10, stop: −85, number of effective pixels: 50%, number of averages: 1, lamp: auto, aperture stop: 100%, surface correction: primary, interpolation: full interpolation, filter: 3 × 3 pixels (boundary processing: target expansion and edge interpolation). The measurement was carried out three times, and the average value was used as the measured value. The measurement results are shown in Table 5.

Test Example 4
The surface fluorine concentrations of the cured films of Examples 12, 16, and 17 were measured by XPS analysis (X-ray photoelectric spectroscopy). The measurement conditions were as follows: apparatus: Quantera SXM (PHI Corporation); excitation X-ray: monochromatic Al Kα _1,2 rays (1486.6 eV); X-ray diameter: 200 μm; photoelectron detection angle: 45° (detector tilt relative to the sample surface); analysis software: MultiPak Version 9.5.0.8 (Ulvac-Phi Corporation); smoothing: 9-point smoothing; horizontal axis correction: C1s main peak (CHx, C-C) at 284.6 eV. The results are shown in Table 6.

Test Example 5
The transmittance of each sample was measured. The transmittance was taken as the L ^* value measured in the transmittance measurement mode of a spectrophotometer (CM-5, Konica Minolta Japan Inc.). The measurement conditions were a viewing angle of 10°, a light source of D65, and a double-sided easy-adhesive PET film as the blank, and the average value of three measurements was taken as the measured value. The measurement results are shown in Table 7.

Test Example 6
The cross section of the cured film obtained in Example 1 was observed with a field emission scanning electron microscope, and the observation results are shown in FIG.
As shown in FIG. 1, it can be seen that the inorganic oxide fine particles filling the inside of the cured film form micro-scale surface irregularities, and nano-scale surface irregularities are further formed on top of these.

Claims (7)

a curable composition comprising a perfluoropolyether (meth)acrylate as a fluorine- containing polymerizable compound and a fluorine -free (meth)acrylate compound as a fluorine-free polymerizable compound, wherein a cured film of the curable composition contains 1 to 200 parts by weight of silicon oxide microparticles having a particle size of 200 nm or less and whose surfaces are modified with (meth)acryloyl groups , per 100 parts by weight of the total of all components of the curable composition excluding the silicon oxide microparticles and the solvent ;
A water-repellent, fluorine-containing, translucent cured film having an arithmetic mean roughness (Ra) of 0.10 μm or more and 0.80 μm or less, as determined by surface measurement of the cured film using a surface roughness measuring device, and a contact angle with water of 139.3 degrees or more after 0 friction cycles . 2. The water-repellent, fluorine-containing, translucent cured film according to claim 1, wherein the arithmetic mean roughness (Ra) determined by measuring the surface of the cured film with a surface roughness measuring device is 0.10 μm or more and 0.80 μm or less, the maximum height roughness (Rz) is 0.50 μm or more and 10.00 μm or less, and the mean element length (Rsm) is 50.0 μm or more and 1000.0 μm or less. The water-repellent, fluorine-containing, translucent cured film according to claim 1 or 2, wherein the arithmetic mean surface height (Sa) within a square surface measuring 555.8 μm x 555.8 μm, as determined by observation of the cured film surface using a white light interference microscope, is 0.01 μm or more and 2.00 μm or less, the root mean square height (Sq) is 0.05 μm or more and 3.00 μm or less, and the maximum cross-sectional height (St) is 1.00 μm or more and 30.00 μm or less. The water-repellent, fluorine-containing, translucent cured film according to any one of claims 1 to 3, wherein the fluorine concentration at the surface of the cured film measured by XPS analysis is 5 to 50 atomic %. The water-repellent, fluorine-containing, translucent cured film according to any one of claims 1 to 4, comprising, as the fluorine-free polymerizable compound, 1,6-hexanediol diacrylate (HDDA), tetrahydrofurfuryl acrylate (THFA), and an amine (meth)acrylate. The water-repellent, fluorine-containing, semi-transparent cured film according to any one of claims 1 to 4, having a thickness of 0.1 to 10 µm. 7. The water-repellent, fluorine-containing, translucent cured film according to claim 1 , which has a transmittance (L* value) of 60 or more in a transmittance measurement mode of a spectrophotometer.