Porous particle dispersion, method for producing a porous particle dispersion, water repellent, porous structure, and method for producing a porous structure

Abstract

To provide: a porous-particle dispersion capable of giving a porous structure having heightened mechanical properties; a method for producing the porous-particle dispersion; a water repellent; a porous structure; and a method for producing the porous structure.SOLUTION: A porous-particle dispersion 14 is for use in making a porous structure having a structure comprising a plurality of porous particles 13 bonded to each other. The porous-particle dispersion 14 comprises a plurality of porous particles 13 and a dispersion medium 12 in which the plurality of porous particles 13 are dispersed. The plurality of porous particles 13 each have a skeleton comprising both a polysiloxane chain and an organic polymerizable functional group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a porous particle dispersion, a method for producing a porous particle dispersion, a water-repellent agent, a porous structure, and a method for producing a porous structure. [Background technology]

[0002] As described in Non-Patent Document 1, a technique for forming a film using a porous particle dispersion is known. These porous particles can be prepared by a sol-gel method using methyltrimethoxysilane. The film obtained from the porous particle dispersion has an aerogel structure and exhibits, for example, water repellency. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] ACS Applied Materials & Interfaces,2011,3,p.539-545 [Overview of the project] [Problems that the invention aims to solve]

[0004] In porous structures such as porous membranes obtained from porous particle dispersions, there is still room for improvement, for example, in terms of enhancing mechanical properties such as abrasion resistance. [Means for solving the problem]

[0005] A porous particle dispersion that solves the above problems is a porous particle dispersion used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded together, and comprises the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, wherein the plurality of porous particles have a skeleton including a polysiloxane chain and an organic polymerizable functional group.

[0006] In the porous particle dispersion described above, D95, which is the 95% particle diameter of the plurality of porous particles, may be 1.5 μm or less. In the porous particle dispersion described above, D95, which is the 95% particle diameter of the plurality of porous particles, may be 1.0 μm or less.

[0007] One embodiment of a method for producing a porous particle dispersion is a method for producing a porous particle dispersion used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded together, wherein the porous particle dispersion contains the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, wherein the plurality of porous particles have a skeleton including a polysiloxane chain and an organic polymerizable functional group, and the production method comprises a porous gel preparation step of preparing a porous gel using a sol-gel method and a grinding step of grinding the porous gel in the dispersion medium, wherein the raw materials used in the sol-gel method may include an alkoxide having the organic polymerizable functional group.

[0008] The water repellent is used to obtain a porous structure having a structure in which a plurality of porous particles are bonded together and which is water-repellent, and comprises the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, wherein the plurality of porous particles have a skeleton including a polysiloxane chain and an organic polymerizable functional group.

[0009] The porous structure is obtained from a porous particle dispersion containing a plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, and the porous structure has a structure in which the plurality of porous particles are bonded together, wherein the plurality of porous particles in the porous particle dispersion have a skeleton containing polysiloxane chains and organic polymerizable functional groups.

[0010] The above-mentioned porous structure may be a porous coating provided on a substrate. A method for manufacturing a porous structure is a method for manufacturing a porous structure having a structure in which a plurality of porous particles are bonded together, comprising: a preparation step of preparing a porous particle dispersion liquid containing the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles; and a bonding step of bonding the plurality of porous particles in the porous particle dispersion liquid in the presence of a radical polymerization initiator, wherein the plurality of porous particles in the porous particle dispersion liquid have a skeleton including a polysiloxane chain and an organic polymerizable functional group.

[0011] In the above-described method for manufacturing a porous structure, the porous structure is a porous coating provided on a substrate, and the method may include a coating step of applying the porous particle dispersion onto the substrate. [Effects of the Invention]

[0012] This invention has the effect of improving the mechanical properties of porous structures. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1(a) is a schematic cross-sectional view illustrating a method for producing a porous particle dispersion, and Figure 1(b) is a schematic view showing an enlarged view of region A1 in Figure 1(a). [Figure 2] Figure 2(a) is a schematic cross-sectional view showing a porous structure, and Figure 2(b) is a schematic cross-sectional view showing an enlarged view of region A2 in Figure 2(a). [Figure 3] Figure 3(a) is a schematic cross-sectional view illustrating a method for manufacturing a porous structure, and Figure 3(b) is a schematic cross-sectional view showing an enlarged view of region A3 in Figure 3(a). [Modes for carrying out the invention]

[0014] The following describes a porous particle dispersion, a method for producing a porous particle dispersion, a water-repellent agent, a porous structure, and one embodiment of the method for producing a porous structure. <Porous particle dispersion> The porous particle dispersion of the present embodiment is used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded. The porous particle dispersion contains a plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles.

[0015] The plurality of porous particles have a skeleton containing a polysiloxane chain and an organic polymerizable functional group. The polysiloxane chain is composed of two or more siloxane bonds (-Si-O-). A hydrogen atom, a hydroxyl group, a methyl group, etc. may be bonded to the silicon atom of the polysiloxane chain. The organic polymerizable functional group is a functional group having an unsaturated double bond. Examples of the organic polymerizable functional group include an acryloyl group (CH2=CHCO-), a methacryloyl group (CH2=C(CH3)CO-), an allyl group (CH2=CHCH2-), a vinyl group (CH2=CH-), etc. The porous particles may have one type of organic polymerizable functional group or two or more types of organic polymerizable functional groups.

[0016] The D95, which is the 95% particle diameter of the plurality of porous particles, is preferably 1.5 μm or less. The D95, which is the 95% particle diameter of the plurality of porous particles, is the particle diameter at which the cumulative frequency in the particle size distribution is 95%. The D95 of the plurality of porous particles is more preferably 1.0 μm or less. The 95% particle diameter of the plurality of porous particles is calculated from the volume-based particle size distribution. The particle size distribution of the porous particles can be measured using the laser diffraction method.

[0017] The plurality of porous particles have pores. The plurality of porous particles are obtained by pulverizing a porous gel. The specific surface area of the porous gel is preferably, for example, 200 m / g or more, more preferably 250 m 2 / g or more, and still more preferably 300 m 2 / g or more. The specific surface area mentioned here is the specific surface area determined using the Brunauer-Emmett-Teller method (BET method). The larger the value of the specific surface area of the porous gel, the easier it is to exhibit the performance based on the porous structure.

[0018] ​ The dispersion medium for porous particle dispersions can be selected and used, for example, depending on the dispersion stability of the porous particles. Examples of dispersion mediums include lower alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, dimethyl ketone, and methyl ethyl ketone; and ethers such as diethyl ether and dipropyl ether. Only one type of dispersion medium may be used, or two or more types may be used in combination.

[0019] The content of multiple porous particles in the porous particle dispersion is preferably 5% by volume or more, more preferably 7% by volume or more, and even more preferably 10% by volume or more. The content of multiple porous particles in the porous particle dispersion is preferably 90% by volume or less, more preferably 85% by volume or less, and even more preferably 80% by volume or less.

[0020] <Method for producing porous particle dispersion> Next, we will explain the method for producing a porous particle dispersion. The method for producing a porous particle dispersion comprises a porous gel preparation step and a grinding step.

[0021] (Porous gel preparation process) The porous gel preparation process involves preparing a porous gel using the sol-gel method. The porous gel has a skeleton containing polysiloxane chains and organic polymerizable functional groups.

[0022] The sol-gel method comprises a hydrolysis step, a dispersion step, and a gelation step. In the sol-gel method, for example, a raw material containing an alkoxide having an organic polymerizable functional group can be used. In the hydrolysis step, the alkoxide is hydrolyzed by adding an acid to the raw material containing the alkoxide having an organic polymerizable functional group.

[0023] Alkoxides having organically polymerizable functional groups can be represented, for example, by the following general formula (1). R 1 n Si(OR 2 )4-n ···(1) R in the general formula (1) 1 is a non-hydrolyzable group having an organic polymerizable functional group. R 1 may be linear, branched, or cyclic. R 1 represents an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms and having an acryloyloxy group or a methacryloyloxy group.

[0024] The number of carbon atoms of the alkyl group having an acryloyloxy group or a methacryloyloxy group is preferably 1 to 10. Examples of the alkyl group having an acryloyloxy group or a methacryloyloxy group include a γ-acryloyloxypropyl group, a γ-methacryloyloxypropyl group, and the like.

[0025] The number of carbon atoms of the alkenyl group is preferably 2 to 10. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a hexenyl group, an octenyl group, and the like. R in the general formula (1) 2 represents an alkyl group having 1 to 6 carbon atoms. n in the general formula (1) represents 1 or 2. R 1 When there are a plurality of R1s, each R1 may be the same as or different from each other. Also, each OR 2 may be the same as or different from each other.

[0026] Examples of the alkoxide having an organic polymerizable functional group include vinyltrimethoxysilane, vinyltriethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and the like. One kind or two or more kinds of the alkoxide having an organic polymerizable functional group can be used.

[0027] It is preferable to use a strong acid such as nitric acid as the acid used in the hydrolysis step. For example, it is preferable to use an aqueous solution of a strong acid with a concentration of 5 mM or more and 10 mM or less. The amount of aqueous strong acid added is not particularly limited, but is, for example, in the range of 0.1 mL or more and 10 mL or less per 1 mL of raw material, and is typically about 1 mL per 1 mL of raw material.

[0028] Next, a dispersion step is performed to disperse the components in the sol obtained in the hydrolysis step. In the dispersion step, a surfactant consisting of an amphiphilic substance other than alcohol is mixed with the sol to disperse the components in the sol. This dispersion step can suppress the precipitation of the components in the sol into particulate matter.

[0029] Examples of surfactants used in the dispersion process include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. One or more types of surfactants can be used.

[0030] Among surfactants, nonionic surfactants are preferred. More preferably, the surfactant contains polyoxyethylene-polyoxypropylene block copolymer, which is a type of nonionic surfactant.

[0031] The surfactant content in the sol is, for example, within the range of 0.01 g to 100 g per 1 mL of raw material in the sol-gel method. The surfactant content in the sol is, for example, within the range of 1% to 70% by mass.

[0032] The gelation process involves adding a base to the sol after the hydrolysis process to gel it. In the gelation process, a porous gel is obtained as the condensation reaction of the components in the sol proceeds.

[0033] The base used in the gelation process is preferably a strong base, more preferably a quaternary ammonium hydroxide, and even more preferably tetramethylammonium hydroxide (TMAOH). For example, it is preferable to use an aqueous TMAOH solution with a concentration of 10 mM to 500 mM.

[0034] The porous gel obtained in the gelation process is preferably subjected to aging for about 24 hours, followed by solvent replacement with, for example, isopropanol. (Grinding process) As shown in Figures 1(a) and 1(b), in the grinding step, the porous gel 11 is ground in the dispersion medium 12. In the grinding step, the porous gel 11 is ground, and multiple porous particles 13 are obtained. In addition, in the grinding step, since the porous gel 11 is ground in the dispersion medium 12, a porous particle dispersion liquid 14 is obtained in which multiple porous particles 13 are dispersed in the dispersion medium 12.

[0035] A wet grinder 51 can be used in the grinding process. Examples of wet grinders 51 include homogenizers, jet mills, ball mills, etc. The homogenizer may be mechanical or ultrasonic. The grinding process may also be carried out by combining different types of wet grinders 51. In the grinding process, for example, the porous particles 13 obtained by grinding the porous gel 11 using a mechanical homogenizer can be further ground using an ultrasonic homogenizer to make the porous particles 13 even finer.

[0036] <Water repellent> Next, we will explain one of the uses of the porous particle dispersion 14 described above: as a water repellent. The water-repellent agent is used to obtain a porous structure that has a structure in which multiple porous particles 13 are bonded together and that is water-repellent.

[0037] The water-repellent agent contains a plurality of porous particles 13 and a dispersion medium 12 for dispersing the plurality of porous particles 13. The plurality of porous particles 13 have a skeleton containing polysiloxane chains and organic polymerizable functional groups. Details of the water-repellent agent and the method for producing the water-repellent agent are the same as those for the porous dispersion and the method for producing the porous dispersion described above.

[0038] Water-repellent agents are used, for example, to impart water-repellency to substrates. The material of the substrate to which the water-repellent agent is applied is not particularly limited and includes, for example, resins, rubber, glass, ceramics, metals, paper, wood, concrete, etc.

[0039] <Porous structure and method for manufacturing a porous structure> As shown in Figures 2(a) and 2(b), the porous structure 21 has a structure in which a plurality of porous particles 13 are bonded together. The porous structure 21 is, for example, a porous coating provided on a substrate 61. The porous structure 21 is obtained from the porous particle dispersion 14.

[0040] The porous structure 21 contains bonds based on organic polymerizable functional groups of a plurality of porous particles 13. The outer surface of the porous structure 21 exhibits, for example, water repellency based on its porous structure. The water repellency of the outer surface of the porous structure 21 can be expressed by the water contact angle. The water contact angle on the outer surface of the porous structure 21 is preferably 110° or more, more preferably 115° or more, and even more preferably 120° or more.

[0041] The porous structure 21 may contain components other than those derived from the porous particles 13. Examples of components other than those derived from the porous particles 13 include a binder made of a non-porous material. However, from the viewpoint of minimizing interference with the performance of the porous particles 13, the content of the binder made of a non-porous material is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of porous particles. The shape of the porous structure 21 is maintained even without the inclusion of a binder due to the bonding based on the organic polymerizable functional groups described above.

[0042] The method for manufacturing the porous structure 21 comprises a preparation step of preparing the porous particle dispersion 14 and a bonding step of bonding a plurality of porous particles 13 in the porous particle dispersion 14 in the presence of a radical polymerization initiator. In the bonding step, a polymerization reaction occurs of the organic polymerizable functional groups of the plurality of porous particles 13. In this polymerization reaction, for example, the organic polymerizable functional group of the first porous particle 13 and the organic polymerizable functional group of the second porous particle 13 adjacent to the first porous particle 13 are polymerized, thereby bonding the first porous particle 13 and the second porous particle 13. The method for manufacturing the porous structure 21 will be described as an example in which the porous structure 21 is a porous coating provided on a substrate 61.

[0043] As shown in Figures 3(a) and 3(b), the process includes a coating step of applying a porous particle dispersion 14 onto a substrate 61. Examples of methods for applying the porous particle dispersion 14 onto the substrate 61 include dip coating, spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0044] The porous particle dispersion 14 contains a radical polymerization initiator. The porous particle dispersion 14 may contain the radical polymerization initiator beforehand. Alternatively, the radical polymerization initiator may be mixed into the porous particle dispersion 14 when using it.

[0045] The radical polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator. Examples of photopolymerization initiators include aromatic ketones, aromatic onium salt compounds, organic peroxides, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, and compounds having carbon-halogen bonds. Specific examples of photopolymerization initiators include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Examples of thermal polymerization initiators include medium-temperature curing organic peroxides and their esters that can be cured at around 50-120°C, and organic azo compounds.

[0046] One or more radical polymerization initiators can be used. Preferably, the radical polymerization initiator is used in an amount of, for example, 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of porous particle dispersion.

[0047] The porous particle dispersion 14 in this embodiment contains a photopolymerization initiator. Therefore, in the bonding step, multiple porous particles 13 can be bonded together by irradiating the porous particle dispersion 14 (coated film) on the substrate 61 with ultraviolet light (UV). More specifically, when ultraviolet light is irradiated onto the porous particle dispersion 14, a polymerization reaction occurs in the organic polymerizable functional groups of the multiple porous particles 13. As a result, for example, adjacent porous particles 13 are bonded together.

[0048] After the bonding process, a drying process is performed to volatilize the dispersion medium 12. The obtained porous structure 21 is preferably subjected to a heat treatment, for example, by heating it at a temperature within the range of 70°C to 150°C. The heat treatment time is preferably within the range of 30 minutes to 6 hours. In this case, for example, it is possible to improve the water repellency of the porous structure 21.

[0049] <Mechanism and Effects> Next, the operation and effects of this embodiment will be described. (1) The porous particle dispersion 14 is used to obtain a porous structure 21 having a structure in which multiple porous particles 13 are bonded together. The porous particle dispersion 14 contains multiple porous particles 13 and a dispersion medium 12 for dispersing the multiple porous particles 13. The multiple porous particles 13 have a skeleton that includes polysiloxane chains and organic polymerizable functional groups. With this configuration, for example, the organic polymerizable functional group of the first porous particle 13 and the organic polymerizable functional group of the second porous particle 13 adjacent to the first porous particle 13 are polymerized, thereby bonding the first porous particle 13 and the second porous particle 13. This makes it easy to increase the bonding force between the porous particles 13. Therefore, it is possible to improve the mechanical properties of the porous structure 21. For example, the abrasion resistance of the porous structure 21 can be improved.

[0050] Here, for example, when obtaining the porous structure 21, it is possible to improve the mechanical properties of the porous structure 21 by using a binder to bind the porous particles 13 together. However, the binder in the porous structure 21 may hinder the performance based on the porous structure of the porous particles 13, so the use of the binder may be restricted. In the porous particle dispersion 14 described above, the mechanical performance of the porous structure 21 can be improved by the binding force between the porous particles 13, so for example, it is possible to reduce the amount of binder used. As a result, the original performance based on the porous structure of the porous particles 13 can be more easily exhibited in the porous structure 21.

[0051] (2) In the porous particle dispersion 14, the D95, which is the 95% particle diameter of the plurality of porous particles 13, is preferably 1.5 μm or less, and more preferably 1.0 μm or less. In this case, the bonding force of the plurality of porous particles 13 can be further increased. Therefore, it is possible to further improve the mechanical properties of the porous structure 21.

[0052] (3) The method for producing the porous particle dispersion 14 comprises a porous gel preparation step of preparing a porous gel 11 using the sol-gel method, and a grinding step of grinding the porous gel 11 in the dispersion medium 12. The raw material used in the sol-gel method preferably contains an alkoxide having an organic polymerizable functional group. In this case, porous particles 13 having a backbone containing a polysiloxane chain and an organic polymerizable functional group can be easily obtained.

[0053] (4) The porous structure 21 obtained from the porous particle dispersion 14 can have its mechanical properties enhanced based on a skeleton containing organic polymerizable functional groups in the plurality of porous particles 13. Such a porous structure 21 can be easily obtained by a manufacturing method that includes a bonding step of bonding the plurality of porous particles 13 in the porous particle dispersion 14 in the presence of a radical polymerization initiator.

[0054] (5) The porous structure 21 is a porous coating provided on the substrate 61, so that functionality based on the porous particles 13 can be easily imparted to the substrate 61. <Example of changes> The above embodiment may be modified and configured as follows. The above embodiment and the following modifications can be combined and implemented to the extent that they do not contradict each other technically.

[0055] The raw materials used in the sol-gel method of the above porous gel preparation step include an alkoxide having an organically polymerizable functional group, but these may be changed to raw materials that do not include this alkoxide having an organically polymerizable functional group. That is, for example, an alkoxide without an organically polymerizable functional group or water glass may be used as the raw materials in the sol-gel method. In this case, for example, the porous gel obtained by the sol-gel method from an alkoxide without an organically polymerizable functional group or water glass may be modified with an alkoxide having an organically polymerizable functional group. Alternatively, for example, the porous gel obtained by the sol-gel method from an alkoxide without an organically polymerizable functional group or water glass may be pulverized and then modified with an alkoxide having an organically polymerizable functional group. Even with such methods, multiple porous particles 13 having organically polymerizable functional groups can be obtained.

[0056] However, from the viewpoint of simplifying or streamlining the manufacturing process of the porous particle dispersion 14, it is preferable to use a raw material containing an alkoxide having an organically polymerizable functional group in the sol-gel method.

[0057] The porous structure 21 is not limited to the shape of a film, such as the porous film described above, and may have a shape other than a film. In this case, the bonding step in the manufacturing method of the porous structure 21 can be changed to, for example, a bonding step in which a plurality of porous particles 13 in the porous particle dispersion 14 are bonded in a mold in the presence of a radical polymerization initiator. This makes it possible to manufacture a porous structure 21 that is compatible with the shape of the mold.

[0058] The applications of the porous structure 21 are not limited to those requiring water-repellent properties. Examples of applications for the porous structure 21 include those requiring protective properties for protective films, those requiring thermal insulation properties for thermal insulation materials, and those requiring specific optical properties. [Examples]

[0059] Next, examples and comparative examples will be described. (Example 1) <Porous gel preparation process> A porous gel was prepared using the sol-gel method. The sol-gel method involves the following steps: hydrolysis, dispersion, and gelation.

[0060] In the hydrolysis step, first, 1.0 mL of vinyltrimethoxysilane (VTMS) was placed in a screw-cap vial. Next, while stirring the VTMS with a stirrer, 1.0 mL of 5 mM nitric acid aqueous solution (HNO3aq) was added, and the mixture was stirred for 12 minutes to prepare a homogeneous sol.

[0061] Next, in the dispersion step, 0.8 g of surfactant was added to the sol and stirred for a further 3 minutes. The surfactant was a nonionic surfactant (Sigma-Aldrich, trade name: Pluronic L-64, molecular weight of polyoxypropylene chain: 1750, ethylene oxide content: 40% by mass). This nonionic surfactant is a polyoxyethylene-polyoxypropylene block copolymer. Subsequently, the sol was cooled by immersing the screw-cap vial in an ice bath and stirring for 10 minutes.

[0062] Next, in the gelation step, 0.6 mL of 100 mM tetramethylammonium hydroxide aqueous solution (TMAOHaq) was added to the sol and stirred for 3 minutes. Subsequently, the stirrer tip was removed from the screw-cap vial and the vial was sealed tightly. The sol was allowed to gel by standing in the screw-cap vial at room temperature for 1 hour. The gel was aged by standing in the screw-cap vial in a 60°C oven for 96 hours. The screw-cap vial was removed from the oven and the gel was immersed in water in a wide-mouthed bottle. The wide-mouthed bottle was sealed tightly and left to stand in a 60°C oven for 24 hours. The water in the wide-mouthed bottle was replaced with a mixed solvent (volume of water:volume of isopropanol (IPA) = 1:1), sealed tightly, and left to stand in a 60°C oven for 8 hours. Next, the mixed solvent in the wide-mouthed bottle was replaced with IPA, sealed tightly, and left to stand in a 60°C oven for 8 hours in a solvent exchange procedure. By performing this solvent exchange procedure a total of three times, a porous gel with IPA (isopropyl alcohol) as the solvent was obtained.

[0063] <Grinding process> In the grinding process, the porous gel was added to 30 mL of IPA, and then the porous gel was first ground using a mechanical homogenizer at 15,000 rpm for 10 minutes to obtain a gel pulverized product. Next, the gel pulverized product was further ground using an ultrasonic homogenizer for 45 minutes to obtain a porous particle dispersion. The porous particle content in the porous particle dispersion was 16.7% by volume.

[0064] <Fabrication of porous structures> 0.3 g of a photopolymerization initiator was added to the porous particle dispersion described above, and the photopolymerization initiator was dissolved by stirring. 2,2-dimethoxy-2-phenylacetophenone was used as the photopolymerization initiator. Next, the porous particle dispersion was left to stand for 24 hours, and then coated onto a substrate using a dip coater. The substrate was a glass slide. The pull-up width of the dip coater was 50 mm, and the pull-up speed was 60 mm / second.

[0065] Next, a porous structure was obtained by performing a bonding process in which the porous particles are bonded together by irradiating the porous particle dispersion on the substrate with ultraviolet light. The wavelength of ultraviolet light used in the bonding process was 365 nm, and the irradiation time was 180 seconds. This polymerized the vinyl groups, which are organic polymerizable functional groups, of the porous particles. After the bonding process, the dispersion medium was volatilized by a drying process in which the substrate with the porous structure was heated. The drying process was carried out using an oven at 60°C for 60 minutes. Furthermore, a heating process was carried out in which the substrate with the porous structure was heated. The heating process was carried out using an oven at 80°C for 1 hour.

[0066] <Measurement of specific surface area> Samples were prepared by drying the above-mentioned porous gel using supercritical fluid drying, and the specific surface area of ​​the samples was measured using nitrogen gas adsorption analysis. Here, since it is difficult to measure the specific surface area of ​​porous particles or porous gel in a wet state, the specific surface area was measured using porous gel dried by supercritical fluid drying. The supercritical fluid drying method was performed using supercritical carbon dioxide under conditions of 80°C, 14 MPa, and 10 hours. This minimizes the change in the pore state of the dry porous gel from the pore state of the wet porous gel.

[0067] For the measurement of specific surface area, the sample was first degassed under vacuum at 80°C for approximately 24 hours, and then measured using a specific surface area measuring device (Microtrac-Bel Co., Ltd., product name: BELSORP-mini). This specific surface area was determined from the adsorbent branches using the BET method. The results of the specific surface area calculation are shown in Table 1.

[0068] <Measurement of particle size distribution> The particle size distribution of the above porous particle dispersion (dispersion medium: IPA) was measured using a laser diffraction particle size distribution analyzer (Shimadzu Corporation, product name: SALD-2200). The calculated 95% particle size (D95) for the porous particles is shown in Table 1.

[0069] <Measurement of contact angle and friction test> The contact angle of the surface of the porous structure sample described above was measured using an automatic contact angle meter (Kyowa Interface Science Co., Ltd., product name: DM-501Hi). The solution used for measuring the contact angle was pure water, with a droplet volume of 1 μL. The elliptic fitting method was used to calculate the contact angle.

[0070] Next, the surface of the porous structure sample was subjected to friction testing using a friction tester (i-tester TL-201Ts, manufactured by Trinity Lab Co., Ltd.). The friction test was performed on a 2cm square flat plate (contact area: 4cm²). 2 A paper wiper (manufactured by Nippon Paper Crecia Co., Ltd., product name: Kimtowels) attached to a ) was used as the contact element. The friction test was performed 30 times back and forth under the conditions of a load of 40g and a stroke of 50mm. The contact angle of the sample after the friction test was measured again as described above. The contact angles of the sample before and after the friction test are shown in Table 1.

[0071] (Example 2) In Example 2, a porous gel was prepared in the same manner as in Example 1. The specific surface area of ​​the porous gel is shown in Table 1. Next, in Example 2, a porous particle dispersion was prepared in the same manner as in Example 1, except that the porous gel underwent a grinding process using an ultrasonic homogenizer for 30 minutes. The calculated 95% particle size (D95) of the porous particles is shown in Table 1. Subsequently, in Example 2, after fabricating a porous structure in the same manner as in Example 1, the contact angle of the porous structure sample was measured and a friction test was performed. The contact angles of the sample before and after the friction test are shown in Table 1.

[0072] (Example 3) In Example 3, a porous gel was prepared in the same manner as in Example 1. The specific surface area of ​​the porous gel is shown in Table 1. Next, in Example 3, a porous particle dispersion was prepared in the same manner as in Example 1, except that the porous gel underwent a grinding process using an ultrasonic homogenizer for 15 minutes. The calculated 95% particle size (D95) of the porous particles is shown in Table 1. Subsequently, in Example 3, after fabricating a porous structure in the same manner as in Example 1, the contact angle of the porous structure sample was measured and a friction test was performed. The contact angles of the sample before and after the friction test are shown in Table 1.

[0073] (Comparative Example 1) In Comparative Example 1, a porous gel was prepared in the same manner as in Example 1, except that vinyltrimethoxysilane (VTMS) was replaced with methyltrimethoxysilane (MTMS). The specific surface area of ​​the porous gel is shown in Table 1. Next, in Comparative Example 1, a porous particle dispersion was prepared in the same manner as in Example 1. The calculation results of the 95% particle size (D95) in the porous particles are shown in Table 1. Subsequently, in Comparative Example 3, after preparing a porous structure in the same manner as in Example 1, the contact angle of the porous structure sample was measured and a friction test was performed. The contact angles of the sample before and after the friction test are shown in Table 1.

[0074] (Comparative Example 2) In Comparative Example 2, the hydrolysis, dispersion, and gelation steps were carried out in the same order as in Example 1, except that the amount of nonionic surfactant added in the dispersion step of Example 1 was changed to 0.4 g. In Comparative Example 2, a mass of aggregated nonporous particles was obtained. The specific surface area of ​​this mass was measured in the same manner as in <Measurement of Specific Surface Area> described above. The results are shown in Table 1.

[0075] In the grinding process, the mass was added to 30 mL of IPA, and then first, the mass was ground using a mechanical homogenizer at 15,000 rpm for 1 hour to obtain a pulverized material. Next, the pulverized material was further ground using an ultrasonic homogenizer for 1 hour to obtain a non-porous particle dispersion. The particle size distribution of the non-porous particles was measured in the same manner as in <Measurement of Particle Size Distribution> described above. The calculated 95% particle size (D95) of the non-porous particles is shown in Table 1.

[0076] Next, in Comparative Example 2, a non-porous structure was prepared in the same manner as described in <Preparation of Porous Structure> above, except that a non-porous particle dispersion was used. Then, the contact angle of the non-porous structure sample was measured and a friction test was performed in the same manner as described in <Measurement of Contact Angle and Friction Test> above. The contact angles of the sample before and after the friction test are shown in Table 1.

[0077] [Table 1] As shown in Table 1, the difference in contact angle α[°] in each example was smaller than the difference in contact angle α[°] in Comparative Example 1. From this result, it can be seen that the surface condition of the samples in each example changed less after the abrasion test from the surface condition before the abrasion test than the sample in Comparative Example 1. In other words, it can be seen that the samples in each example have superior abrasion resistance compared to the sample in Comparative Example 1. [Explanation of Symbols]

[0078] 11…Porous gel 12...Dispersion medium 13...Porous particles 14...Porous particle dispersion liquid 21...Porous structure 61...Base material

Claims

1. A porous particle dispersion liquid used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded together by bonding a plurality of porous particles in the presence of a radical polymerization initiator, The present invention comprises the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, The plurality of porous particles are a dispersion of porous particles having a backbone containing polysiloxane chains and organically polymerizable functional groups.

2. The porous particle dispersion according to claim 1, wherein D95, which is the 95% particle diameter of the plurality of porous particles, is 1.5 μm or less.

3. The porous particle dispersion according to claim 1, wherein D95, which is the 95% particle diameter of the plurality of porous particles, is 1.0 μm or less.

4. A method for producing a porous particle dispersion used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded together by bonding a plurality of porous particles in the presence of a radical polymerization initiator, The porous particle dispersion comprises the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles. The plurality of porous particles have a skeleton containing polysiloxane chains and organic polymerizable functional groups, The aforementioned manufacturing method is A porous gel preparation step in which a porous gel is prepared using the sol-gel method, The process includes a grinding step of grinding the porous gel in the dispersion medium, The raw material used in the sol-gel method is a method for producing a porous particle dispersion containing an alkoxide having an organic polymerizable functional group.

5. A water repellent used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded together and which is water-repellent, by bonding a plurality of porous particles in the presence of a radical polymerization initiator, The present invention comprises the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, The plurality of porous particles are a water repellent having a skeleton containing polysiloxane chains and organically polymerizable functional groups.

6. A porous structure having a structure in which the plurality of porous particles are bonded together is obtained by bonding the plurality of porous particles in a porous particle dispersion liquid containing a plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles in the presence of a radical polymerization initiator, The plurality of porous particles in the porous particle dispersion are porous structures having a skeleton containing polysiloxane chains and organically polymerizable functional groups.

7. The porous structure according to claim 6, wherein the porous structure is a porous coating provided on a substrate.

8. A method for manufacturing a porous structure having a structure in which multiple porous particles are bonded together, A preparation step of preparing a porous particle dispersion liquid containing the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, The method comprises a bonding step of bonding the plurality of porous particles in the porous particle dispersion in the presence of a radical polymerization initiator, A method for producing a porous structure, wherein the plurality of porous particles in the porous particle dispersion have a skeleton containing polysiloxane chains and organic polymerizable functional groups.

9. The porous structure is a porous coating provided on a substrate, The method for manufacturing a porous structure according to claim 8, further comprising a coating step of applying the porous particle dispersion onto the substrate.

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