Patent Application
20160032146
The present invention relates generally to an organic/inorganic transparent hybrid films, and a process for producing them. More particularly, the invention relates to an organic/inorganic transparent film that is obtained by coating a precursor solution prepared by cohydrolysis and polycondensation of an organosilane and a metal alkoxide in a solution containing an organic solvent, water and a catalyst onto the surface of a solid comprising a substrate such as a metal, a metal oxide film, a metal oxide, an alloy, a semiconductor, a polymer, a ceramics, a glass, a resin, a wood, a paper or a fiber to form a transparent film of improved adhesion, simultaneously with volatilization of the solvent, while controlling the mobility of functional groups derived from the organosilane on the surface of the transparent film, and that allows the surface of the substrate to have a variety of improved properties such as water repellency/oil repellency, ability of liquid droplets to roll off, anti-fingerprint properties, defogging properties, corrosion resistance and durability, and a process for producing the same.
The present invention provides a novel technique and a novel product relating to a new surface modification technology because by formation on the surface of the substrate of an organic/inorganic transparent film having a variety of improved properties such as adhesion to substrates, water repellency/oil repellency, ability of liquid droplets to roll off, anti-fingerprint properties, defogging properties, corrosion resistance and durability, they produce notable effects in the automobile and construction material glass fields and other applications where it is typically desired to improve raindrop removal capability and defogging properties thereby making sure the field of vision and preventing sticking of stain, dirt or the like, prevent corrosion of metal materials and wood-based materials, improve releasability of materials out of nanoimprinting molds, and impart anti-fingerprint properties to touch panel displays, etc.
As liquid droplets deposit onto the surface of a solid, it sets off corrosion, degradation and pollution of the solid surface from there, and as liquid droplets deposit onto a glass or other transparent material, it gives rise to poor visibility; development of materials and surface treatments having high liquid droplets removal capability have been tried in many engineering fields.
The dynamic behavior (dynamic dewettability) in particular of liquid droplets on a solid surface has recently been increasingly valued in as an index to droplets removal performance, and that behavior may be estimated in terms of contact angle hysteresis (Non-Patent Publication 1). Hysteresis may be represented by a difference (θA−θR) between the advancing contact angle (θA) and the receding contact angle (θR); the smaller the value, the more likely the liquid droplets are to roll off the solid surface even upon a bit of tilting. In other words, a solid surface having a small hysteresis will have high droplets removal performance. On a solid surface having a large hysteresis, on the other hand, liquid droplets are “pinned down”, and this holds true even for an ultra-water repellent surface having a static contact angle greater than 150°.
For instance, water repellent treatment of a hydrophilic glass or other solid surface is now increasingly practiced using an organosilane terminated with a functional group of low surface energy such as an alkyl group or a perfluoroalkyl group. However, minuscule water droplets have been known to remain on a solid surface even when there is an angle of tilt greater than 90°; so it has been found that such water repellent treatment does not always result in improvements in water droplets removal performance.
Recent, if not many, reports have indicated that the density and dynamic behavior of functional groups grafted to a solid surface have some considerable influences on dynamic dewettability. For instance, McCarthy et al. have investigated a hysteresis change due to a density change of trimethylsilyl groups grafted by vapor treatment onto a silicon substrate, and have discovered that there is the optimum density at which there is the smallest hysteresis present (Non-Patent Publication 2).
This has been interpreted as follows: when the density of the grafted trimethylsilyl groups is higher than the optimum, their mobility becomes low due to too short intermolecular distances, resulting in a large hysteresis, and when the density of the grafted trimethylsilyl groups is low, a portion of the solid surface not covered by trimethylsilyl groups is exposed to give rise to strong interactions between liquid droplets and polar functional groups on the solid surface, ending up with a large hysteresis.
McCarthy et al. as well as the inventors have made use of vapor treatment to graft onto a solid surface branched bulky molecules (for instance, tris(trimethylsiloxy)sylylethylenedimethylsilane (Non-Patent Publication 3), bis(tridecafluoro-1,1,2,2-tetrahydrooctyl)-dimethylsiloxy)methylsilane (Patent Publication 1 and Non-Patent Publication 4), and cyclic molecules (tetramethylcyclotetrasiloxane (Non-Patent Publication 5)), resulting successfully in the creation of a solid surface of very small hysteresis. Such a solid surface having high liquid droplet removal performance is achieved by the “molecular umbrella effect” coming out of the bulkiness of the grafted functional groups.
From these reports, it has been appreciated that bringing the mobility (or fluidity) of functional groups grafted onto a solid surface close to “liquid-like” would be important for the purpose of improving the dynamic dewettability of the solid surface; there is a demand for solid surface treatment capable of achieving such a “liquid-like” state. However, most studies have placed emphasis on a search for molecules capable of dynamic dewettability improvements; there is no or little study case of making use of existing surface treating agents or functional molecules having functional groups with a view to dynamic dewettability improvements.
Problems with the surface modification methods as described above are that 1) there is some limitation on the type of substrates to be treated thanks to a difference in reactivity between an organosilane compound and the substrate surface, 2) the raw materials to be used are limited to a bulky organosilane compound or polymer having a branched/cyclic structure, and 3) a molecular film, because of being a few nm in thickness, may peel off or be damaged for some chemical or physical reasons, and maintenance of surface functions over an extended period of time may be difficult. In the field to which the invention pertains, there is still a mounting demand for development of a surface modification method capable of achieving stable liquid droplet removal performance, corrosion resistance, water repellency/oil repellency in combination with the surfaces of practical substrates in a stable manner over an extended period of time.
Situations being like this and with the prior art in mind, the inventors have devoted themselves to studies with a view to developing an unheard-of, new surface treatment technique for practical substrates that makes it possible to form metal surfaces or glass surfaces having no or little hysteresis, resulting in a discovery of a novel finding that a precursor solution obtained by co-hydrolysis and polycondensation of an organosilane and a metal alkoxide in a solution containing an organic solvent, water and a catalyst is coated onto the surface of a substrate and allowed to stand at room temperature under atmospheric pressure for a given time, whereby 1) simultaneously with volatilization of the solvent, there is a transparent film of improved adhesion formed, and 2) the surface of the transparent film obtained in 1) is by far smaller in hysteresis than the surface of a substrate covered by a monolayered film composed of the same organosilane molecules. Further, the inventors have made study after study to bring the invention up to completion.
An object of the invention is to provide a novel surface modification technique wherein as compared with coating of a monolayered film of an organosilane onto a substrate (there was usually a hysteresis of 10° or more occurred), a transparent organic/inorganic hybrid film is formed by coating only, and the resulting solid surface has a very small hysteresis relative to a liquid having a surface tension of 18 to 73 dynes/cm. Another object of the invention is to provide a surface modification technique capable of forming a surface having a very small hysteresis: a surface having a value of a contact angle hysteresis (θA−θR) smaller than that of a surface treated by the organosilane alone as measured in terms of a dynamic contact angle (an advancing contact angle (θA) and a receding contact angle (θR)).
Yet another object of the invention is to provide a new technique and a new product relating to a very useful, novel surface modification technology for industrial applications where it is typically desired to reduce or minimize the interactions between liquid droplets and a solid surface, thereby to improve the ability of automotive glass and construction material glass to remove raindrops and to defog and keep them clean for the field of vision and prevention of sticking of dirt, stain or the like, control water flows through μ-TAS, biochips or the like, control micro-water drops through nozzles, etc. for water-soluble ink jets, prevent corrosion of metals and wood-based materials, improve the releasability of materials out of nanoimprinting molds, impart anti-fingerprint properties to touch panel displays, and so on.
The invention having for its objects to solve the prior art problems comprises the following technical means.
The invention will now be explained in further details.
The present invention provides an organic/inorganic transparent hybrid film, characterized in that it is a film obtained by co-hydrolysis and polycondensation of an organosilane and a metal alkoxide mixed together at a given molar ratio in a solution containing an organic solvent, water and a catalyst, said film ensuring that a difference (hysteresis) between the advancing contact angle and the receding contact angle relative to a liquid having a surface tension of 18 to 73 dynes/cm has a smaller value than that of a surface treated by the organosilane alone. The present invention also provides a method for producing a transparent organic/inorganic hybrid film, characterized by subjecting an organosilane and a metal alkoxide to co-hydrolysis and polycondensation in a solution containing an organic solvent, water and a catalyst to form a precursor solution with a controlled inter-organosilane distance, coating the precursor solution onto a solid surface, and allowing the solid surface to stand at room temperature under atmospheric pressure for a given time for volatilization of the solvent and cross-linkage of the resulting film. Further, the present invention provides a solid surface coated with the aforesaid organic/inorganic transparent hybrid film, characterized by having improved water repellency/oil repellency, ability of liquid droplets to roll off, liquid droplet removal capability, anti-fingerprint properties, defogging properties and corrosion resistance.
The invention embodied as described above makes sure formation of an organic/inorganic transparent hybrid film improved in terms of adhesion and mobility of functional groups derived from the organosilane on the film surface, so that the difference (hysteresis) between the advancing and receding contact angles relative to various liquid droplets (having a surface tension of 18 to 37 dynes/cm) and a mixed liquid comprising a mixture of two or more of these liquids can have a value smaller than that of a surface treated by the organosilane alone.
In preferable embodiments of the invention, the organosilane and metal alkoxide are mixed together at any molar ratio of 1:0.1 or more, and more preferably 1:0.1 to 100; the resultant organic/inorganic transparent hybrid film has adhesion good enough to adhere readily to a substrate selected from within the group consisting of a metal, a metal oxide film, an alloy, a semiconductor, a polymer, a ceramics, a glass, a resin, a wood, a fiber and a paper; and the aforesaid film has adhesion good enough to adhere to a hybrid surface composed of at least one surface selected from within the group consisting of a planar surface, a curved surface, a concave/convex surface and a porous surface.
In preferable embodiments of the invention, there is a change in the inter-organosilane distance depending on the molar ratio between the organosilane and the metal alkoxide; the difference (hysteresis) between the advancing and receding contact angles of the surface of the aforesaid organic/inorganic transparent hybrid film relative to various liquid droplets (having a surface tension of 18 to 73 dynes/cm), a mixture of at least two of these liquids or a hybrid surface of these liquids hybridized with a solid(s) has a value smaller than that of a surface treated by the organosilane alone or fingerprints are less likely to adhere to it; the organic/inorganic transparent hybrid film has de-misting capability; and when there is damage to the surface to such an extent that the difference (hysteresis) between the advancing and receding contact angles increases or is incalculatable, the damaged surface is removed off to expose a new surface with a difference (hysteresis) between the advancing and receding contact angles having a value smaller than that of a surface treated by the organosilane alone.
In the invention, it is preferable that the organo-silane that provides a raw material of the organic/inorganic transparent hybrid film is represented by the following formula (A): R1—Si—R23-nR3n where n is equal to 1, 2 or 3, R1 stands for an alkyl chain having 1 to 30 carbon atoms or a perfluoro group having 1 to 20 carbon atoms, R2 stands for an alkyl group having 1 to 6 carbon atoms, and R3 stands for an alkoxy group having 1 to 15 carbon atoms, a chloro group, an isocyanato group or an acetoxy group and that includes an inert functional group bound via an Si—C bond and a functional group forming at least one Si—OH group after hydrolysis, or the following formula (B): R1R2—Si—R3nR43-n where n is equal to 1, 2 or 3, R1 stands for a hydroxyl group, a vinyl group, an alkyl chloride group, an amino group, an imino group, a nitro group, a mercapto group, an epoxy group, a carbonyl group, a methacryloxy group, an azido group, a diazo group or a benzopheny group and a derivative thereof, R2 stands for an alkylene group having 1 to 15 carbon atoms (—CnH2n—), R3 stands for an alkyl group having 1 to 6 carbon atoms, and R4 stands for an alkoxy group having 1 to 15 carbon atoms, a chloro group, an isocyanato group or an acetoxy group, and that includes an active functional group bound via an Si—C bond and a functional group forming at least one Si—OH group after hydrolysis.
In the invention, it is preferable that the metal alkoxide that provides a raw material of the organic/inorganic transparent hybrid film is represented by the following formula (C): M(R1)n where n is equal to 1, 2, 3 or 4, M stands for a metal element Al, Ca, Fe, Ge, Hf, In, Si, Ta, Ti, Sn, or Zr, and R stands for an alkoxy group having 1 to 15 carbon atoms.
In the invention, a precursor solution obtained by co-hydrolysis and polycondensation of an organosilane and a metal alkoxide in a solution containing an organic solvent, water and a catalyst is added dropwise to the surface of a solid selected from within the group consisting of a metal, a metal oxide film, an alloy, a semiconductor, a polymer, a ceramics, a glass, a resin, a wood, a paper and a fiber, and then allowed to stand at room temperature under atmospheric pressure for a given time for volatilization of the solvent. In the invention, it is preferable that there is an organic solvent used, which solvent is miscible with a small amount of water used for the hydrolysis, can dissolve a substance after the hydrolysis and polycondensation of the organosilane and metal alkoxide, and has a vapor pressure higher than that of water, and that the molar fraction of water used for the hydrolysis is greater than that of the alkoxy group in the precursor solution composition.
In the invention, the catalyst used for the hydrolysis includes a catalyst having an action on acceleration of hydrolysis of R3 in the aforesaid formula (A), R4 in the aforesaid formula (B) and R1 in the aforesaid formula (C). In the invention, it is preferable that the volatilization of the solvent is accelerated by any one process selected from within the group consisting of a spin coating process, a dip coating process, a roller coating process, a bar coating process, an ink jet coating process, a gravure coating process, and a spraying process, and that a film thickness is controlled between 10 nm and 10,000 nm depending on the concentration of the organosilane and metal alkoxide in the precursor solution.
While the organosilane that may be used herein, for instance, is preferably an alkyl (3 to 18 carbon atoms) alkoxysilane or the like, it is to be appreciated that any other organosilanes may similarly be used with the proviso that they are equal or similar in effect thereto. By way of example, these organosilanes include such compounds as mentioned below.
By way of example but not by way of limitation, the organosilanes include an alkyl (having 1 to 30 carbon atoms) trimethoxysilane, an alkyl (having 1 to 30 carbon atoms) triethoxysilane, an alkyl (having 1 to 30 carbon atoms) methyldimethoxysilane, an alkyl (having 1 to 30 carbon atoms) methyldiethoxysilane, an alkyl (having 1 to 30 carbon atoms) dimethyldimethoxysilane, an alkyl (having 1 to 30 carbon atoms) dimethylethoxysilane, an alkyl (having 1 to 30 carbon atoms) trichlorosilane, an alkyl (having 1 to 30 carbon atoms) methyldichlorosilane, an alkyl (having 1 to 30 carbon atoms) dimethylchlorosilane, an alkyl (having 1 to 30 carbon atoms) triacetoxysilane, an alkyl (having 1 to 30 carbon atoms) methyldiacetoxy-silane, an alkyl (having 1 to 30 carbon atoms) dimethylacetoxysilane, an alkyl (having 1 to 30 carbon atoms) triisocyanatosilane, an alkyl (having 1 to 30 carbon atoms) methyldicyanatosilane, an alkyl (having 1 to 30 carbon atoms) dimethylcyanatosilane, a perfluoro (having 3 to 18 carbon atoms) trimethoxysilane, a perfluoro (having 3 to 18 carbon atoms) triethoxysilane, a perfluoro (having 3 to 18 carbon atoms) methyldi-methoxsilane, a perfluoro (having 3 to 18 carbon atoms) dimethylethoxysilane, a perfluoro (having 3 to 18 carbon atoms) trichlorosilane, a perfluoro (having 3 to 18 carbon atoms) methyldichlorosilane, a perfluoro (having 3 to 18 carbon atoms) dimethylchlorosilane, a perfluoro (having 3 to 18 carbon atoms) triacetoxysilane, a perfluoro (having 3 to 18 carbon atoms) methyldi-acetoxysilane, a perfluoro (having 3 to 18 carbon atoms) dimethylacetoxysilane, a perfluoro (having 3 to 18 carbon atoms) triisocyanatosilane, a perfluoro (having 3 to 18 carbon atoms) methyldicyanatosilane, and a perfluoro (having 3 to 18 carbon atoms) dimethylcyanatosilane.
The metal alkoxide usable herein may include, but not limited to, ones known so far in the art. By way of example, metal alkoxides including two or more alkoxy groups with a metal element as center, except those mentioned in [0026], may be used, and the following compounds having the same or similar effects may be used as well.
By way of example only, the metal alkoxides include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-t-butoxysilane, triethoxyaluminum, tri-n-propoxyaluminum, tri-i-propoxyaluminum, tri-n-butoxyaluminum, tri-t-butoxyaluminun, dimethoxycalcium, diethoxycalcium, di-i-propoxycalcium, di-n-butoxycalcium, triethoxy iron, tetramethoxygermanium, tetraethoxy-germanium, tetra-i-propoxygermanium, tetra-n-butoxygermanium, tetra-t-butoxygermanium, tetramethoxyhafnium, tetraethoxyhafnium, tetra-i-propoxyhafnium, tetra-n-butoxyhafnium, tetra-t-butoxyhafnium, trimethoxyindium, triethoxyindium, tri-i-propoxyindium, tri-n-butoxyindium, tri-t-butoxyindium, pentamethoxytantalum, pentaethoxy-tantalum, penta-i-propoxytantalumn, penta-t-butoxytantalum, penta-n-butoxytantalum, tetramethoxytitanium, tetraetoxytitanium, tetra-i-propoxytitanium, tetra-n-butoxytitanium, tetra-t-butoxytitanium, tetramethoxytin, tetraethoxytin, tetra-i-propoxytin, tetra-n-butoxytin, and tetra-t-butoxytin.
In order to form a transparent yet uniform film according to the invention, it is preferable that the organic solvent is miscible with a small amount of water, can dissolve a polycondensation product of the organosilane and metal alkoxide, and is rapidly volatilized off upon coating of the precursor solution onto the substrate. In other words, it is preferable that the precursor solution is prepared using an organic solvent having a vapor pressure higher than that of water such as methanol, ethanol, isopropanol, and tetrahydro-furan.
If the concentrations of the organosilane and metal alkoxide are adjusted, it is then possible to control the film thickness between 10 nm and 10,000 nm. This is because when a certain amount of the precursor solution is added dropwise to the surface of the substrate for formation of a film by volatilization of the solvent, the higher the concentrations of the organosilane and metal alkoxide that are solid components contained in the precursor solution, the more solid gets precipitated on the surface of the substrate.
In the invention it is desired to make use of a catalyst for the purpose of accelerated hydrolysis of reactive functional groups of the organosilane and metal alkoxide (formation of M-OH groups where M is a metal element). It is also desirable to control the pH of the precursor solution by that catalyst thereby stabilizing the polycondensation product of the organo-silane and metal alkoxide. For instance, when there is an alkoxysilyl group used, it is preferable to use an acid such as hydrochloric acid thereby adjusting pH to 1 to 3.
The amount of water to be added should preferably be greater than the number of functional groups for the purpose of hydrolyzing all of reactive functional groups contained in the precursor solution to form M-OH groups where M is a metal element. An amount of water less than defined above may result in the formation of a film, but it is not preferable because insufficient hydrolysis will cause an unhydrolyzed portion of the organosilane and metal alkoxide to be volatilized during treatment, leading to poor yields.
In the precursor solution during the hydrolysis and polycondensation, a portion of the organo-silane and metal alkoxide after the hydrolysis undergoes random polycondensation. This is because the post-hydrolysis metal alkoxide and the post-polycondensation organosilane are subjected to alternate polycondensation, spacing the organic groups derived from the organosilane away from each other.
It follows that the metal alkoxide behaves as a “spacer” to space the organic groups of the organosilane away from each other.
According to the invention, therefore, it is possible to vary the amount of the metal alkoxide to be added to the organosilane thereby controlling the inter-organosilane distance as desired. It is in turn possible to adjust the mobility on the film surface of the functional groups derived from the organosilane thereby brining the film surface close to the so-called “liquid-like” surface, so resulting in improvements in dynamic dewettability.
In the invention, there is no particular limitation on how to form films provided that there is an acceleration of volatilization of the solvent. For instance, preferable examples include, but not limited to, a spin coating process, a dip coating process, a roller coating process, a bar coating process, an ink jet coating process, a gravure coating process, and a spraying process.
As the substrate usable herein, use may be made, as desired, of appropriate materials such as metals, metal oxide films, alloys, semiconductors, polymers, ceramics, glass, resins, wood, paper and fibers. Specific examples of the substrate include, but not limited to, copper, brass, silicon, polycarbonate, glass, silicone resin,
Japanese cypress, and ribbons. These substrates may be shaped as desired; for instance, they may be in plate, concave/convex, powdery, tubular, porous, fibrous or other forms. There is no need for any pretreatment of the substrate; of course, the substrate may be washed by means of plasma, UV or the like.
In the invention, a layer structure with an interlayer distance of 1 to 10 nm may occur although depending on the type of organosilane, because silanol formed after the hydrolysis of the organosilane has hydrophilicity, whereas the organic groups have hydrophobicity with the result that upon film formation, the polycondensation product of the organosilane and metal alkoxide behaves amphipathically and self-assembles using the hydrophobic interaction of the organic groups as a driving force. The organosilane preferable for formation of such a layer structure, for instance, includes an alkylalkoxysilane having 4 to 18 carbon atoms. Although again depending on the type of organosilane. On the other hand, there may be an amorphous hybrid film formed with no formation of any layer structure, said hybrid film being free from any nanometer order regularity. However, it has been found that whether or not there is regularity has no influence on dynamic dewettability at all.
As described above, the organosilane usable herein, for instance, includes organosilanes having active functional groups in addition to the alkylalkoxysilane. Preferable examples of the organosilane usable herein are vinyltriethoxysilane, and 2-hydroxy-4-(3-triethoxysilyl-propoxy)-diphenylketone. Other organosilanes having active functional groups such as hydroxyl groups, aldehyde groups, alkyl chloride groups, amino groups, imino groups, nitro groups, mercapto groups, epoxy groups, carbonyl groups, methacryloxy groups, azido groups, diazo groups or benzopheny groups may also be used.
Further, the organosilane may be replaced by an organic carboxylic acid or an organic phosphonic acid or compounds represented by the following formula (D) R1-R2 where R1 stands for an alkyl chain having 1 to 30 carbon atoms or a perfluoroakyl group having 1 to 20 carbon atoms (CF3(CF2)n— where n is equal to 0 to 19, and R2 stands for carboxyl (—COOH), phosphonic acid (—P(O)(OH)2), or phosphoric acid (—O—P(O)(OH)2)).
The present invention produces such advantages as mentioned below.
While the present invention will now be explained with reference to specific examples, it is to be noted that the following examples are given for the purpose of illustration alone, but not by way of limitation.
Various organosilanes and metal alkoxides (mainly tetramethoxysilane) were mixed together at given ratios (Table 1), and the mixtures were blended with ethanol and hydrochloric acid before the blends were stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to Milli-Q water and n-hexadecane in Example 1 are tabulated in Table 1. As shown in Table 1, it has been confirmed that surfaces having a small hysteresis are formed over a wide range of molar ratios (metal alkoxide/organosilane=0.1 to 100).
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto the surfaces of various substrates shown in Table 2, and then allowed to stand at room temperature for one day.
The values of advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to Milli-Q water and n-hexadecane in Example 2 are tabulated in Table 2. As shown in Table 2, it has been confirmed that surfaces having a small hysteresis are formed irrespective of substrate. In particular, the effects on copper, brass, silicon, polycarbonate, glass, and silicone resin having a flat surface were found to be notable.
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was dip coated onto a glass tube, and then allowed to stand at room temperature for one day.
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to liquids having different surface tensions in Example 4 are tabulated in Table 3. As shown in Table 3, it has been confirmed that surfaces having a small hysteresis are formed irrespective of liquid's surface tension.
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to a mixed liquid comprising a mixture of two or more liquids in Example 5 are tabulated in Table 4. As shown in Table 4, it has been confirmed that surfaces having a small hysteresis are formed even on the mixed liquid comprising a mixture of two or more liquids.
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
N-(2-aminoethyl)3-aminopropyltrimethoxysilane, tetramethoxysilane (tetramethoxysilan/N-(2-aminoethyl)3-aminopropyltrimethoxysilane-4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
Decyltriethoxysilane, ethyltriethoxysilane and tetramethoxysilane or decyltrimethoxysilane, aminopropyltrimethoxysilane and tetramethoxysilane were mixed together at given ratios (Table 5), and the mixture was blended with ethanol and hydrochloric acid, followed by to stirring at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to Milli-Q water and n-hexadecane in Example 8 are tabulated in Table 5. As shown in Table 5, it has been confirmed that even when two organosilanes are mixed together, there is a surface having a small hysteresis formed.
Decyltriethoxysilane and two metal alkoxides were mixed together at given ratios (Table 6), and blended with ethanol and hydrochloric acid. Then, the blend was stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and allowed to stand at room temperature for one day.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to Milli-Q water and n-hexadecane in Example 9 are tabulated in Table 6. As shown in Table 6, it has been confirmed that even when two metal alkoxides are mixed together, there is a surface having a small hysteresis formed.
Decyltriethoxysilane and tetramethoxysilane were mixed together at given ratios (Table 7), and blended with ethanol and hydrochloric acid. Then, the blend was stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The film thicknesses of various samples in Example 10 are tabulated in Table 7. As shown in Table 7, it has been confirmed that the film thickness can be controlled as desired by the molar ratios between the organosilane and the metal alkoxide.
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. After the obtained precursor solution was allowed to stand at room temperature for a given time (1 day to 180 days), it was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to Milli-Q water and n-hexadecane in Example 11 are tabulated in Table 8. As shown in Table 8, it has been confirmed that even when the precursor solution was stored for 180 days or longer, there is a surface having a small hysteresis formed.
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane=4, 5 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
The XRD patterns of various samples in Example 12 are presented in
Decyltriethoxysilane, tetramethoxysilane (tetramethoxysilane/decyltriethoxysilane-4 (molar ratio)), ethanol and hydrochloric acid were mixed together, and the mixture was then stirred at room temperature for a given time. The obtained solution was spin coated onto a glass substrate, and then allowed to stand at room temperature for one day.
After the treatment, the surface of the substrate was exposed to vacuum ultraviolet light (VUV) of 172 nm in wavelength at 1,000 Pa for 10 seconds. A portion of the surface damaged by VUV irradiation was removed by a scotch tape. The advancing (θA) and receding (θR) contact angles and hysteresis of the sample relative to Milli-Q water and n-hexadecane before and after the VUV irradiation and after surface removal were found to have such values as set out in Table 9.
As shown in Table 9, it has been confirmed that even when damage to the surface gave rise to a large hysteresis, removal of the damaged site causes a new surface to reappear with the result that the dynamic dewettability of the surface is restored (regeneration of a surface having a small hysteresis).
Zirconium tetrapropoxide (about 70% 1-propanol solution hereinafter referred to as ZTP for short) and carboxylic acids (CH3(CH2)nCOOH, where n=6, 8, 10, 12, 14, 16, 20, 22, were mixed together, and the mixture was stirred at 70° C. in a nitrogen atmosphere for a given time, just after which the solution (referred hereinafter to as ZrCAx where x=8, 10, 12, 14, 16, 18, 22, 24) was transferred in a Teflon™ vessel, which was in turn allowed to stand in a 150° C. oven for 12 hours in a closed state.
That vessel was allowed to stand at 80° C. for an additional 12 hours with the lid held open for full removal of the remaining IPA. Glacial acetic acid was added to this solution, which was stirred at 60° C. for 5 minutes. Finally, IPA was added to the solution at a proportion of 1:14 (ZrCAx:IPA) to obtain the end solution. The thus obtained solution was spin coated onto a substrate washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, dried at 60° C. for 10 minutes, and heat treated at 100° C. for 1 hour.
The values of the advancing (θA) and receding (θR) contact angles and hysteresis of various samples relative to n-hexadecane, n-dodecane and n-decane in Example 14 are tabulated in Table 10, and the XRD pattern of the sample where x=18 in Example 14 is presented in Table 6.
As shown in Table 10 and
After various glass substrates were cleaned by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, organosilane vapors shown in Table 11 were chemically adsorbed from a vapor phase onto the glass substrates. The treatment temperature was 80° C. and the treatment time was 72 hours. The values of dynamic contact angles of various samples relative to Milli-Q water and n-hexadecane in Comparative Example 1 are tabulated in Table 11, and the post-treatment advancing (θA) and receding (θR) contact angles and hysteresis of the surfaces of the substrates were found to have such values as set out in Table 11.
As shown in Table 11, it has been confirmed that when the surfaces of the substrates are treated by the organosilane alone, all the surfaces formed have a large hysteresis.
After various substrates were exposed to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for a given time, decyltriethoxysilane vapors were chemically adsorbed from a vapor phase onto the substrates. The treatment temperature was 80° C. and the treatment time was 72 hours. The values of dynamic contact angles of various samples relative to Milli-Q water and n-hexadecane in Comparative Example 2 are tabulated in Table 12, and the post-treatment advancing (θA) and receding (θR) contact angles and hysteresis of the surfaces of the substrates were found to have such values as set out in Table 12.
As shown in Table 12, when the surfaces of the substrates are treated by the organosilane alone, surfaces having a small roughness like glass or silicone surfaces have a small hysteresis, but that hysteresis is still larger as compared with the organic/inorganic hybrid films. The surfaces of other substrates have a large hysteresis, indicating that there are surfaces having poor dynamic dewettability formed.
After the inner wall of a glass tube was degreased by acetone, decyltriethoxysilane vapor was chemically adsorbed from a vapor phase onto the glass tube. The treatment temperature was 80° C. and the treatment time was 72 hours. Added dropwise into the glass tube was n-hexadecane (0.5 mL) stained by Sudan III.
As shown in
After various glass substrates were washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, decyltriethoxysilane vapors were chemically adsorbed from a vapor phase onto the glass substrates. The treatment temperature was 80° C. and the treatment time was 72 hours. The values of dynamic contact angles of various samples relative to various liquids having different surface tensions in Comparative Example 4 are tabulated in Table 13, and the post-treatment advancing (θA) and receding (θR) contact angles and hysteresis of the surfaces of the substrates were found to have such values as set out in Table 13.
As shown in Table 13, when the surface of interest was treated by the organosilane alone, the values of hysteresis relative to the liquids having different surface tensions were larger as compared with the organic/inorganic hybrid film. Especially, it has been found that use of liquid droplets having a surface tension smaller than that of n-decane gives rise to a full wetting spreading of them over the surface.
After various glass substrates were washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, decyltriethoxysilane vapors were chemically adsorbed from a vapor phase onto the glass substrates. The treatment temperature was 80° C. and the treatment time was 72 hours.
The values of dynamic contact angles of various samples relative to mixed liquids comprising a mixture of two or more liquids in Comparative Example 5 are tabulated in Table 14, and the post-treatment advancing (θA) and receding (θR) contact angles and hysteresis of the surfaces of the substrates relative to mixed liquids comprising a mixture of two or more liquids were found to have such values as set out in Table 14.
As shown in Table 14, when the surface of interest was treated by the organosilane alone, the hysteresis relative to liquids having different surface tensions had a larger value as compared with the organic/inorganic hybrid film.
After various glass substrates were washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, decyltriethoxysilane vapors were chemically adsorbed from a vapor phase onto the glass substrates. The treatment temperature was 80° C. and the treatment time was 72 hours. After the post-treatment glass substrates were let stand, fingers were pressed against their surfaces to observe their anti-fingerprint property were left.
As shown in
After various glass substrates were washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, N-(2-aminoethyl)3-aminopropyltrimethoxysilane vapors were chemically adsorbed from a vapor phase onto the glass substrates. The post-treatment glass substrates were exposed to a vapor having a relative humidity of 100% to observe changes in transparency of the substrates.
As shown in
After various glass substrates were washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, mixed vapors of decyltriethoxysilane and ethyltriethoxysilane were chemically adsorbed from a vapor phase onto the glass substrates. The treatment temperature was 80° C. and the treatment time was 72 hours. The values of dynamic contact angles of various samples in Comparative Example 8 are tabulated in Table 15. The advancing (θA) and receding (θR) contact angles and hysteresis of the surfaces of the post-treatment samples relative to Milli-Q water and n-hexadecane were found to have such values as set out in table 15.
As shown in Table 15, when the surface of interest was treated by the organosilane alone, the surface treated had a larger hysteresis as compared with the organic/inorganic hybrid film.
After various glass substrates were washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, decyltriethoxysilane vapors were chemically adsorbed from a vapor phase onto the glass substrates. The treatment temperature was 80° C. and the treatment time was 72 hours.
The surface of the post-treatment substrate was exposed to VUV of 172 nm in wavelength at 1,000 Pa for 10 seconds, after which a scotch tape was used to remove off a portion of the surface damaged by VUV irradiation. The advancing (θA) and receding (θR) contact angles and hysteresis of the substrate relative to Milli-Q water and n-hexadecane before and after VUV irradiation and before surface removal were found to have such values as set out in Table 16.
As shown in Table 16, it has been clear that once the surface treated by the organosilane alone is damaged incurring degradation of dynamic dewettability, that property cannot be restored back.
ZTP and IPA were blended with each other at a proportion of 1:14 (ZTP:IPA) to obtain a solution. The obtained solution was spin coated onto a glass substrate washed by exposure to vacuum ultraviolet light of 172 nm in wavelength at 1,000 Pa for 30 minutes, then dried at 60° C.□ for 10 minutes, and then heated at 100° C. for 1 hour. The solvents: n-hexadecane, n-dodecane and n-decane were all wettingly spread over the obtained surface.
The surfaces of the substrate samples prepared in Examples 1-14 and Comparative Examples 1-10 were relatively estimated. From the results of Examples 1-10 and 12-14 and Comparative Examples 1-10, it has been found that the addition of the metal alkoxide to the organosilane ensures that the hysteresis is smaller as compared with the surface treated by the organosilane alone, resulting in the achievement of a surface having improved water repellency/oil repellency, resistance to fingerprint adhesion and de-misting capability. From Example 11 it has been found that the more the concentration of tetramethoxysilane that provides a solid component after film formation, the greater the film thickness becomes. It follows that the film thickness is controllable depending on the concentration of the solid component. It has further been found that as shown in Example 12, there may be a layer structure formed under certain specific conditions.
Commonly, it has be considered that the addition of the metal alkoxide that is an inorganic component would incur poor dynamic dewettability due to an increase in the hydroxyl groups (—OH) exposed on a solid surface. However, the obtained results indicate the opposite: improvements in dynamic dewettability. This has revealed that the addition of the inorganic component makes the inter-organic site distance derived from the organosilane longer with the result that the mobility of the organic sites increases considerably, leading to improvements in the ability to remove liquid droplets.
As shown in Example 1 in particular, even the addition of the metal alkoxide to the organosilane in an amount of 100 folds (molar ratio) resulted in the formation of a surface having a small hysteresis. As shown further in Examples 10 and 14, even when different metal alkoxide types were mixed together or an organic carboxylic acid(s) was used in place of the organosilane for film preparation, there was again a film having a small hysteresis obtained. Thus, the results of Examples 1-10 and 14 indicate that this mechanism is not limited to a specific organosilane/metal alkoxide proportion; so it may be applied not only to every organosilane molecule but to organic carboxylic acids and organic phosphonic acids as well.
It has generally been known that surface treatment by the organosilane alone has difficulty in application to surfaces having a large roughness or substrate surfaces having a low reactivity. Indeed, it has also been found from the results of Comparative Example 2 that substrates having a small roughness like glass or silicon may be treated to a certain degree although there is a somewhat large hysteresis occurring. However, other substrates have a noticeably large hysteresis or liquid droplets are wettingly spread over them.
From a comparison of Example 2 with Comparative Example 2, it has been appreciated that the treatment described herein may render it possible to obtain surfaces having a small hysteresis irrespective of their substrate. As can also be seen from Examples 4 and 11 in particular, it has been appreciated that the treatment technology described herein is very versatile because the precursor solution can be stored over an extended period of time without recourse to any special treatment processes and conditions.
As described in greater details, the invention relates to an organic/inorganic transparent hybrid film and a method for producing the same. According to the invention, it is possible to provide an organic/inorganic transparent film obtained by coating a precursor solution obtained by co-hydrolysis and polycondensation of an organosilane and a metal alkoxide in a solution containing an organic solvent, water and a catalyst onto a surface of a substrate such as a metal, a metal oxide film, an alloy, a semiconductor, a polymer, a ceramics, a glass, a resin, a wood, a paper and a fiber, in which a transparent film of good adhesion is formed simultaneously with volatilization of the solvent, and by control of mobility of functional groups derived from the organosilane on the film surface, improved water repellency/oil repellency, ability of liquid droplets to roll off, liquid droplet removal capability, anti-fingerprint properties and defogging properties can be imparted to the surface of the substrate while the properties of the substrate are kept intact, and a method for producing the same.
The present invention provides a new technique and a new product relating to a very useful, novel surface modification technology for industrial applications where it is typically desired to reduce or minimize the interactions between liquid droplets and a solid surface, thereby to improve the ability of automotive glass and construction material glass to remove raindrops and to defog and keep them clean for the field of vision and prevention of sticking of dirt, stain or the like, control water flows through μ-TAS, biochips or the like, control micro-water drops through nozzles, etc. for water-soluble ink jets, prevent corrosion of metals and wood-based materials, improve the releasability of materials out of nanoimprinting molds, impart anti-fingerprint properties to touch panel displays, and so on.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/056537 | 3/8/2013 | WO | 00 |
