JP2023173662A - Porous-particle dispersion, method for producing porous-particle dispersion, water repellent, porous structure, and method for producing porous structure - Google Patents

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

The present invention relates to a porous particle dispersion, a method for producing a porous particle dispersion, a water repellent, a porous structure, and a method for producing a porous structure.

As described in Non-Patent Document 1, a technique for forming a membrane using a porous particle dispersion is known. This porous particle can be prepared by a sol-gel method using methyltrimethoxysilane. The membrane obtained from the porous particle dispersion has an airgel structure and exhibits, for example, water repellency.

ACS Applied Materials & Interfaces,2011,3,p.539-545

In porous structures such as porous membranes obtained from porous particle dispersions, there is still room for improvement in terms of improving mechanical properties such as friction resistance, for example.

A porous particle dispersion liquid that solves the above problems is a porous particle dispersion liquid used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded, the plurality of porous particles, a dispersion medium for dispersing the plurality of porous particles, the plurality of porous particles having a skeleton containing a polysiloxane chain and an organic polymerizable functional group.

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

One embodiment of the 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, the method comprising: The dispersion liquid contains the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, and the plurality of porous particles have a skeleton containing a polysiloxane chain and an organic polymerizable functional group. The manufacturing method includes a porous gel preparation step of preparing a porous gel using a sol-gel method, and a pulverization step of pulverizing the porous gel in the dispersion medium, and the manufacturing method is used in the sol-gel method. The raw material may include the alkoxide having the organic polymerizable functional group.

A water repellent is a water repellent used to obtain a porous structure having a structure in which a plurality of porous particles are combined and has water repellency, and is a water repellent used to obtain a porous structure having a structure in which a plurality of porous particles are combined and a porous structure that has water repellency. a dispersion medium for dispersing the porous particles, and the plurality of porous particles have a skeleton containing a polysiloxane chain and an organic polymerizable functional group.

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 has a structure in which the plurality of porous particles are combined. In the porous structure, the plurality of porous particles in the porous particle dispersion have a skeleton containing a polysiloxane chain and an organic polymerizable functional group.

The porous structure may be a porous coating provided on a base material.
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, the method comprising: a 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 in the presence of a radical polymerization initiator. The plurality of porous particles in the solid particle dispersion have a skeleton containing a polysiloxane chain and an organic polymerizable functional group.

In the method for producing a porous structure, the porous structure is a porous coating provided on a base material, and the porous structure may include a coating step of applying the porous particle dispersion onto the base material. good.

The present invention has the effect of making it possible to improve the mechanical properties of a porous structure.

FIG. 1(a) is a schematic cross-sectional view illustrating a method for producing a porous particle dispersion, and FIG. 1(b) is a schematic diagram showing an enlarged area A1 in FIG. 1(a). FIG. 2(a) is a schematic cross-sectional view showing a porous structure, and FIG. 2(b) is a schematic cross-sectional view showing an enlarged area A2 in FIG. 2(a). FIG. 3(a) is a schematic cross-sectional view illustrating a method for manufacturing a porous structure, and FIG. 3(b) is a schematic cross-sectional view showing an enlarged area A3 in FIG. 3(a).

Hereinafter, one embodiment of a porous particle dispersion, a method for producing a porous particle dispersion, a water repellent, a porous structure, and a method for producing a porous structure will be described.
<Porous particle dispersion>
The porous particle dispersion liquid of this embodiment is used for obtaining a porous structure having a structure in which a plurality of porous particles are bonded together. The porous particle dispersion liquid contains a plurality of porous particles and a dispersion medium in which the plurality of porous particles are dispersed.

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 (CH ₂ =CHCO-), a methacryloyl group (CH ₂ =C(CH ₃ )CO-), an allyl group (CH ₂ =CHCH ₂ -), and a vinyl group (CH ₂ =CH-) and the like. The porous particles may have one type of organic polymerizable functional group, or may have two or more types of organic polymerizable functional groups.

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

The plurality of porous particles have pores. A plurality of porous particles are obtained by crushing a porous gel. The specific surface area of the porous gel is, for example, preferably 200 m ² /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 referred to here is a 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 more easily the performance based on the porous structure is exhibited.

The dispersion medium for the porous particle dispersion can be selected and used depending on, for example, the dispersion stability of the porous particles. Examples of the dispersion medium 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.

The content of the plurality of porous particles in the porous particle dispersion is preferably 5% by volume or more, more preferably 7% by volume or more, and still more preferably 10% by volume or more. The content of the plurality of porous particles in the porous particle dispersion is preferably 90% by volume or less, more preferably 85% by volume or less, and still more preferably 80% by volume or less.

<Method for producing porous particle dispersion>
Next, a method for producing a porous particle dispersion will be explained.
The method for producing a porous particle dispersion includes a porous gel preparation step and a pulverization step.

(Porous gel preparation process)
In the porous gel preparation step, a porous gel is prepared using a sol-gel method. The porous gel has a skeleton containing polysiloxane chains and organic polymerizable functional groups.

The sol-gel method includes a hydrolysis process, a dispersion process, and a gelation process. 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, an acid is added to a raw material containing an alkoxide having an organic polymerizable functional group to hydrolyze the alkoxide.

The alkoxide having an organic polymerizable functional group is represented by the following general formula (1), for example.
R ¹ _n Si(OR ² ) _4-n ...(1)
R ¹ in general formula (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, having an acryloyloxy group or a methacryloyloxy group.

The alkyl group having an acryloyloxy group or a methacryloyloxy group preferably has 1 to 10 carbon atoms. Examples of the alkyl group having an acryloyloxy group or a methacryloyloxy group include a γ-acryloyloxypropyl group and a γ-methacryloyloxypropyl group.

The alkenyl group preferably has 2 to 10 carbon atoms. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a hexenyl group, and an octenyl group.
R ² in general formula (1) represents an alkyl group having 1 to 6 carbon atoms. n in general formula (1) represents 1 or 2. When there is a plurality of ^R1 's, each R1 may be the same or different from each other. Further, each OR ² may be the same or different from each other.

Examples of the alkoxide having an organic polymerizable functional group include vinyltrimethoxysilane, vinyltriethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and the like. One type or two or more types of alkoxides having an organic polymerizable functional group can be used.

As the acid used in the hydrolysis step, it is preferable to use a strong acid such as nitric acid. As the strong acid, it is preferable to use, for example, a strong acid aqueous solution within the range of 5 mM or more and 10 mM or less. The amount of the strong acid aqueous solution to be added is not particularly limited, but is within a range of, for example, 0.1 mL or more and 10 mL or less per 1 mL of the raw material, and is, for example, about 1 mL per 1 mL of the raw material.

Next, a dispersion step is performed to disperse the components in the sol obtained in the hydrolysis step. The dispersion step is a step in which components in the sol are dispersed by mixing a surfactant made of an amphiphilic substance other than alcohol with the sol. This dispersion step can prevent components in the sol from precipitating in the form of particles.

Surfactants used in the dispersion step include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. One kind or two or more kinds of surfactants can be used.

Among the surfactants, nonionic surfactants are preferred. More preferably, the surfactant includes a polyoxyethylene/polyoxypropylene block copolymer, which is a type of nonionic surfactant.

The content of the surfactant in the sol is, for example, in the range of 0.01 g or more and 100 g or less per 1 mL of the raw material for the sol-gel method. The content of the surfactant in the sol is, for example, in the range of 1% by mass or more and 70% by mass or less.

The gelling step is a step of gelling the sol by adding a base to the sol after the hydrolysis step. In the gelling step, a porous gel is obtained as a condensation reaction of components in the sol progresses.

The base used in the gelling step is preferably a strong base, more preferably quaternary ammonium hydroxide, and still more preferably tetramethylammonium hydroxide (TMAOH). As the base, it is preferable to use, for example, a TMAOH aqueous solution within the range of 10 mM or more and 500 mM or less.

After the porous gel obtained in the gelling step is aged for about 24 hours, it is preferable to replace the solvent with, for example, isopropanol.
(Crushing process)
As shown in FIGS. 1(a) and 1(b), in the pulverizing step, the porous gel 11 is pulverized in a dispersion medium 12. In the pulverization step, the porous gel 11 is pulverized to obtain a plurality of porous particles 13. Furthermore, in the pulverization step, the porous gel 11 is pulverized in the dispersion medium 12, so that a porous particle dispersion 14 in which a plurality of porous particles 13 are dispersed in the dispersion medium 12 is obtained.

A wet crusher 51 can be used in the crushing process. Examples of the wet crusher 51 include a homogenizer, a jet mill, and a ball mill. The homogenizer may be mechanical or ultrasonic. Further, the crushing process may be performed by combining different types of wet crushers 51. In the pulverization step, for example, a plurality of porous particles 13 obtained by pulverizing the porous gel 11 using a mechanical homogenizer are further pulverized using an ultrasonic homogenizer. can be made into finer particles.

<Water repellent>
Next, a water repellent, which is one of the uses of the porous particle dispersion 14, will be explained.
The water repellent is used to obtain a porous structure having a structure in which a plurality of porous particles 13 are bonded together and has water repellency.

The water repellent contains 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 have a skeleton containing a polysiloxane chain and an organic polymerizable functional group. The details of the water repellent and the method for producing the water repellent are the same as those for the porous dispersion and the method for producing the porous dispersion described above.

A water repellent agent, for example, used to impart water repellency to a substrate. The material of the base material to which the water repellent is applied is not particularly limited, and examples thereof include resin, rubber, glass, ceramics, metal, paper, wood, concrete, and the like.

<Porous structure and method for manufacturing porous structure>
As shown in FIGS. 2(a) and 2(b), the porous structure 21 has a structure in which a plurality of porous particles 13 are combined. The porous structure 21 is, for example, a porous coating provided on the base material 61. The porous structure 21 is obtained from the porous particle dispersion 14 described above.

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

The porous structure 21 may contain components other than those derived from the porous particles 13 described above. In the porous structure 21, components other than those derived from the porous particles 13 include, for example, a binder made of a non-porous material. However, from the viewpoint of suppressing the performance of the porous particles 13 from being inhibited, the content of the binder made of a non-porous material should be, for example, 10 parts by mass or less with respect to 100 parts by mass of the porous particles. is preferable, and more preferably 5 parts by mass or less. The shape of the porous structure 21 is maintained even without containing a binder due to the bonds based on the organic polymerizable functional groups described above.

The method for manufacturing the porous structure 21 includes a preparation step of preparing the porous particle dispersion 14, and bonding a plurality of porous particles 13 in the porous particle dispersion 14 in the presence of a radical polymerization initiator. Equipped with a bonding process. In the bonding step, a polymerization reaction of the organic polymerizable functional groups of the plurality of porous particles 13 is performed. 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. As a result, the first porous particles 13 and the second porous particles 13 are combined. The method for manufacturing the porous structure 21 will be described using an example in which the porous structure 21 is a porous film provided on the base material 61.

As shown in FIGS. 3(a) and 3(b), a coating step of coating the porous particle dispersion 14 on the base material 61 is provided. Examples of methods for applying the porous particle dispersion 14 onto the base material 61 include dip coating, spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, and die coating. , gravure coating method.

The porous particle dispersion 14 contains a radical polymerization initiator. The porous particle dispersion 14 can contain a radical polymerization initiator in advance. Note that a radical polymerization initiator may be mixed in when the porous particle dispersion 14 is used.

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, ketooxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, carbon Examples include compounds having a halogen bond. Specific examples of the photopolymerization initiator include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethyl Examples include benzoyldiphenylphosifine oxide. Examples of the thermal polymerization initiator include medium-temperature curing type organic peroxides that can be cured at about 50 to 120°C, esters thereof, and organic azo compounds.

One kind or two or more kinds of radical polymerization initiators can be used. The radical polymerization initiator is preferably used in an amount of, for example, 0.01 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the porous particle dispersion.

The porous particle dispersion liquid 14 of this embodiment contains a photopolymerization initiator. Therefore, in the bonding step, the plurality of porous particles 13 can be bonded by irradiating the porous particle dispersion liquid 14 (coating film) on the base material 61 with ultraviolet rays (UV). Specifically, by irradiating the porous particle dispersion liquid 14 with ultraviolet rays, a polymerization reaction of the organic polymerizable functional groups of the plurality of porous particles 13 is performed. As a result, for example, adjacent porous particles 13 are bonded together.

After performing the bonding step, a drying step is performed to volatilize the dispersion medium 12. The obtained porous structure 21 is preferably subjected to heat treatment at a temperature within a range of 70° C. or higher and 150° C. or lower, for example. The heat treatment time is preferably within a range of, for example, 30 minutes or more and 6 hours or less. In this case, for example, it becomes possible to improve the water repellency of the porous structure 21.

<Action and effect>
Next, the functions and effects of this embodiment will be explained.
(1) The porous particle dispersion 14 is used to obtain a porous structure 21 having a structure in which a plurality of porous particles 13 are combined. The porous particle dispersion liquid 14 contains 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 have a skeleton containing a polysiloxane chain and an organic polymerizable functional group. According to 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. By doing so, the first porous particles 13 and the second porous particles 13 are combined. Thereby, the bonding force between the porous particles 13 can be easily increased. Therefore, it becomes possible to improve the mechanical properties of the porous structure 21. For example, the friction resistance of the porous structure 21 can be improved.

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 that binds the porous particles 13 together. However, since the binder in the porous structure 21 may inhibit the performance based on the porous structure of the porous particles 13, the use of the binder may be limited. In the porous particle dispersion liquid 14 described above, the mechanical performance of the porous structure 21 can be improved due to the bonding force between the porous particles 13, so that, for example, it is possible to reduce the amount of binder used. . This makes it easier for the porous structure 21 to exhibit its original performance based on the porous structure of the porous particles 13.

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

(3) The method for producing the porous particle dispersion 14 includes a porous gel preparation step of preparing the porous gel 11 using a sol-gel method, and a pulverization step of pulverizing the porous gel 11 in a dispersion medium 12. ing. 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 skeleton containing a polysiloxane chain and an organic polymerizable functional group can be easily obtained.

(4) The porous structure 21 obtained from the porous particle dispersion 14 has improved mechanical properties based on the skeleton containing organic polymerizable functional groups in the plurality of porous particles 13. becomes possible. Such a porous structure 21 can be easily obtained by a manufacturing method including 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.

(5) Since the porous structure 21 is a porous film provided on the base material 61, functionality based on the porous particles 13 can be easily imparted onto the base material 61.
<Example of change>
The above embodiment may be modified and configured as follows. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

- The raw materials used in the sol-gel method in the porous gel preparation step include an alkoxide having an organic polymerizable functional group, but may be changed to a raw material that does not contain the alkoxide having an organic polymerizable functional group. That is, as a raw material used in the sol-gel method, for example, an alkoxide having no organic polymerizable functional group or water glass can also be used. In this case, for example, an alkoxide having no organic polymerizable functional group or a porous gel obtained from water glass by a sol-gel method may be modified with an alkoxide having an organic polymerizable functional group. Further, for example, after pulverizing an alkoxide having no organic polymerizable functional group or a porous gel obtained from water glass by a sol-gel method, it may be modified with an alkoxide having an organic polymerizable functional group. Even with such a method, a plurality of porous particles 13 having organic polymerizable functional groups can be obtained.

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

- 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 the film. In this case, the bonding step in the method for manufacturing the porous structure 21 may be, for example, a bonding step in which a plurality of porous particles 13 in the porous particle dispersion 14 are bonded in the presence of a radical polymerization initiator in a mold. Can be changed. Thereby, the porous structure 21 can be manufactured according to the shape of the mold.

- The application of the porous structure 21 is not limited to applications requiring water repellency. Applications of the porous structure 21 include, for example, applications where the protective performance of a protective film is required, applications where insulation performance such as a heat insulating material is required, applications where specific optical properties are required, and the like.

Next, examples and comparative examples will be explained.
(Example 1)
<Porous gel preparation process>
Porous gels were prepared using the sol-gel method. In the sol-gel method, the following hydrolysis step, dispersion step, and gelation step are performed.

In the hydrolysis step, first, 1.0 mL of vinyltrimethoxysilane (VTMS) was placed in a screw tube bottle. Next, while stirring the VTMS with a stirrer, 1.0 mL of a 5 mM aqueous nitric acid solution (HNO ₃ aq) was added, and the mixture was stirred for 12 minutes to prepare a uniform sol.

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

Next, in the gelation step, 0.6 mL of a 100 mM tetramethylammonium hydroxide aqueous solution (TMAOHaq) was added to the sol, followed by stirring for 3 minutes. Subsequently, after removing the stirrer chip inside the screw tube bottle, the screw tube bottle was tightly stoppered. The sol was gelatinized by allowing this screw tube bottle to stand at room temperature for 1 hour. The gel was aged by leaving the screw bottle in an oven at 60° C. for 96 hours. The screw tube bottle was removed from the oven and the gel was immersed in the water in the wide mouth bottle. The wide-mouthed bottle was tightly stoppered and left in an oven at 60°C for 24 hours. The water in the wide-mouth bottle was replaced with a mixed solvent (volume of water: volume of isopropanol (IPA) = 1:1), and after the bottle was tightly stoppered, the bottle was left standing in an oven at 60°C for 8 hours. Next, a solvent exchange operation was performed in which the mixed solvent in the wide-mouthed bottle was replaced with IPA, and after the bottle was tightly capped, the bottle was left standing in an oven at 60°C for 8 hours. By performing this solvent exchange operation three times in total, a porous gel in which the solvent was exchanged with IPA was obtained.

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

<Preparation of porous structure>
0.3 g of a photopolymerization initiator was added to the porous particle dispersion, and the photopolymerization initiator was dissolved by stirring. 2,2-dimethoxy-2-phenylacetophenone was used as a photopolymerization initiator. Next, after leaving this porous particle dispersion for 24 hours, the porous particle dispersion was applied onto the substrate using a dip coater. The base material is a glass slide. The pulling width of the dip coater is 50 mm, and the pulling speed is 60 mm/sec.

Next, a porous structure was obtained by performing a bonding step of bonding the porous particles by irradiating the porous particle dispersion on the base material with ultraviolet rays.
The wavelength of ultraviolet rays in the bonding step is 365 nm, and the irradiation time of ultraviolet rays is 180 seconds. As a result, the vinyl group, which is an organic polymerizable functional group possessed by the porous particles, was polymerized. After the bonding step, the dispersion medium was volatilized by performing a drying step of heating the base material with the porous structure. The drying process was performed using an oven at 60° C. for 60 minutes. Furthermore, a heating step was performed to heat the base material with the porous structure. The heating step was performed using an oven at 80° C. for 1 hour.

<Measurement of specific surface area>
A sample was prepared by drying the porous gel using a supercritical drying method, and the specific surface area of the sample was measured using a nitrogen gas adsorption analysis method. 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 a porous gel dried by a supercritical drying method. The supercritical drying method was performed using supercritical carbon dioxide under the conditions of 80° C., 14 MPa, and 10 hours. Thereby, changes in the state of the pores of the porous gel in the dry state from the state of the pores in the porous gel in the wet state can be suppressed as much as possible.

To measure the specific surface area, first, the sample was degassed under vacuum at 80°C for about 24 hours, and then measured using a specific surface area measuring device (manufactured by Microtrac Bell Co., Ltd., trade name: BELSORP-mini). . This specific surface area is determined from the adsorption branches using the BET method. Table 1 shows the calculation results of the specific surface area.

<Measurement of particle size distribution>
The particle size distribution of the porous particle dispersion (dispersion medium: IPA) was measured using a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name: SALD-2200). Table 1 shows the calculation results of the 95% particle diameter (D95) of the porous particles.

<Measurement of contact angle and friction test>
The contact angle of the surface of the sample of the porous structure was measured using an automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name: DM-501Hi). The solution used to measure the contact angle was pure water, and the droplet volume was 1 μL. An ellipse fitting method was used to calculate the contact angle.

Next, a friction test was performed on the surface of the sample of the porous structure using a friction tester (manufactured by Trinity Lab Co., Ltd., i-tester TL-201Ts). In the friction test, a paper wiper (trade name: Kim Towel, manufactured by Nippon Paper Crecia Co., Ltd.) attached to a 2 cm square flat plate (contact area: 4 cm ² ) was used as a contact. The friction test was performed 30 times under the conditions of a load of 40 g and a stroke of 50 mm. Contact angles were further measured as described above on the samples after the friction test. Table 1 shows the contact angles of the samples before and after the friction test.

(Example 2)
In Example 2, a porous gel was prepared in the same manner as in Example 1. Table 1 shows the specific surface area of the porous gel. Next, in Example 2, a porous particle dispersion liquid was prepared in the same manner as in Example 1, except that the porous gel was subjected to a pulverization step using an ultrasonic homogenizer for 30 minutes. Table 1 shows the calculation results of the 95% particle diameter (D95) of the porous particles. Subsequently, in Example 2, a porous structure was produced in the same manner as in Example 1, and then a contact angle and a friction test were performed on a sample of the porous structure. Table 1 shows the contact angles of the samples before and after the friction test.

(Example 3)
In Example 3, a porous gel was prepared in the same manner as in Example 1. Table 1 shows the specific surface area of the porous gel. Next, in Example 3, a porous particle dispersion liquid was prepared in the same manner as in Example 1, except that the porous gel was subjected to a pulverization step using an ultrasonic homogenizer for 15 minutes. Table 1 shows the calculation results of the 95% particle diameter (D95) of the porous particles. Subsequently, in Example 3, a porous structure was produced in the same manner as in Example 1, and then a contact angle and a friction test were performed on a sample of the porous structure. Table 1 shows the contact angles of the samples before and after the friction test.

(Comparative example 1)
In Comparative Example 1, a porous gel was prepared in the same manner as in Example 1, except that vinyltrimethoxysilane (VTMS) in Example 1 was changed to methyltrimethoxysilane (MTMS). Table 1 shows the specific surface area of the porous gel. Next, in Comparative Example 1, a porous particle dispersion liquid was prepared in the same manner as in Example 1. Table 1 shows the calculation results of the 95% particle diameter (D95) of the porous particles. Subsequently, in Comparative Example 3, a porous structure was produced in the same manner as in Example 1, and then a contact angle and a friction test were performed on a sample of the porous structure. Table 1 shows the contact angles of the samples before and after the friction test.

(Comparative example 2)
In Comparative Example 2, the hydrolysis step, dispersion step, and gelation step were performed in order in the same manner as in Example 1, except that the amount of nonionic surfactant added in the dispersion step in Example 1 was changed to 0.4 g. Ta. In Comparative Example 2, a lump of a plurality of non-porous particles was obtained. The specific surface area of this mass was measured in the same manner as <Measurement of specific surface area> above. The results are shown in Table 1.

In the pulverization step, the mass was added to 30 mL of IPA, and then the mass was first pulverized using a mechanical homogenizer at 15,000 rpm for 1 hour to obtain a pulverized product. Next, the pulverized product was further pulverized 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> above. Table 1 shows the calculation results of the 95% particle diameter (D95) of non-porous particles.

Subsequently, in Comparative Example 2, a non-porous structure was prepared in the same manner as in <Preparation of porous structure> above except that a non-porous particle dispersion was used, and then the above <Measurement of contact angle was performed. and friction test>, contact angle measurements and friction tests were performed on samples of non-porous structures. Table 1 shows the contact angles of the samples before and after the friction test.

As shown in Table 1, the contact angle difference α [°] in each Example was smaller than the contact angle difference α [°] in Comparative Example 1. From this result, it can be seen that the surface condition of the samples of each Example is less likely to change from the surface condition before the abrasion test than the sample of Comparative Example 1 after the abrasion test. That is, it can be seen that the samples of each Example have better wear resistance than the sample of Comparative Example 1.

DESCRIPTION OF SYMBOLS 11...Porous gel 12...Dispersion medium 13...Porous particles 14...Porous particle dispersion liquid 21...Porous structure 61...Substrate

Claims (9)

A porous particle dispersion liquid used for obtaining a porous structure having a structure in which a plurality of porous particles are combined,
containing the plurality of porous particles and a dispersion medium that disperses the plurality of porous particles,
A porous particle dispersion in which the plurality of porous particles have a skeleton containing a polysiloxane chain and an organic polymerizable functional group. The porous particle dispersion according to claim 1, wherein D95, which is a 95% particle diameter of the plurality of porous particles, is 1.5 μm or less. The porous particle dispersion according to claim 1, wherein D95, which is a 95% particle diameter of the plurality of porous particles, is 1.0 μm or less. A method for producing a porous particle dispersion liquid used for obtaining a porous structure having a structure in which a plurality of porous particles are combined, the method comprising:
The porous particle dispersion liquid contains the plurality of porous particles and a dispersion medium that disperses the plurality of porous particles,
The plurality of porous particles have a skeleton containing a polysiloxane chain and an organic polymerizable functional group,
The manufacturing method includes:
a porous gel preparation step of preparing a porous gel using a sol-gel method;
a pulverizing step of pulverizing the porous gel in the dispersion medium,
A method for producing a porous particle dispersion, in which the raw material used in the sol-gel method contains the alkoxide having the organic polymerizable functional group. A water repellent agent used for obtaining a porous structure having a structure in which a plurality of porous particles are combined and having water repellency,
containing the plurality of porous particles and a dispersion medium that disperses the plurality of porous particles,
The plurality of porous particles are water repellent agents having a skeleton including a polysiloxane chain and an organic polymerizable functional group. A porous structure obtained from a porous particle dispersion containing a plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles, and having a structure in which the plurality of porous particles are combined. hand,
The plurality of porous particles in the porous particle dispersion are porous structures having a skeleton including a polysiloxane chain and an organic polymerizable functional group. The porous structure according to claim 6, wherein the porous structure is a porous coating provided on a base material. A method for producing a porous structure having a structure in which a plurality of porous particles are combined,
a preparation step of preparing a porous particle dispersion containing the plurality of porous particles and a dispersion medium for dispersing the plurality of porous particles;
a bonding step of bonding the plurality of porous particles in the porous particle dispersion in the presence of a radical polymerization initiator;
The method for producing a porous structure, wherein the plurality of porous particles in the porous particle dispersion have a skeleton containing a polysiloxane chain and an organic polymerizable functional group. The porous structure is a porous coating provided on a base material,
The method for manufacturing a porous structure according to claim 8, comprising a coating step of coating the porous particle dispersion on the base material.

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