JP2020196851A - Coating composition and coating agent - Google Patents

Abstract

To provide a coating composition and a coating agent each of which has excellent storage stability, can be used easily and conveniently, and can hydrophilize solid surface with high performance.SOLUTION: A coating composition described in a claim 1 contains a polyvinyl alcohol, a polyfunctional group-containing compound having two or more functional groups capable of reacting with a hydroxyl group, a water, and a volatile solvent. The coating composition has such a blending ratio of each component that the blending ratio of the volatile solvent and the water is volatile solvent: water=100: 25 to 400 (weight ratio), and the blending ratio of the volatile solvent and the water, the polyvinyl alcohol, and the polyfunctional group-containing compound is the volatile solvent and water: polyvinyl alcohol: polyfunctional group-containing compound=100: 0.1 to 5.0: 0.005 to 0.5 (weight ratio).SELECTED DRAWING: None

Description

The present invention relates to a coating composition and a coating agent capable of easily and easily hydrophilizing the surface of an article.

The technique of making a solid surface hydrophilic is used for the purpose of controlling the adhesiveness and adhesion of a solid, controlling the printability, imparting biocompatibility, suppressing non-specific adsorption of biorelated molecules such as proteins, and the like. ..
Polyvinyl alcohol (PVA) is widely known as a compound used for such hydrophilization. PVA is widely used in various fields because it has excellent processability and mechanical and chemical stability, is also excellent in biocompatibility, and is inexpensive. However, since PVA is easily dissolved in water or an organic solvent, there is a problem that even if a hydrophilic film is formed on the solid surface, it is immediately dissolved. Therefore, in order to form a hydrophilized film using PVA, it is necessary to insolubilize the film, and various proposals have been made for this purpose.
For example, Patent Document 1 describes a novel polymer gel that can be easily produced from an inexpensive material under normal pressure without using a special device, and can be preferably used as an adsorbent for heavy metal ions, phosphate ions, and the like. As a result, the hydroxyl group of the polymer substance having a plurality of hydroxyl groups is crosslinked by the reaction with the boronic acid group of the compound having two or more boronic acid groups in the molecule, and the hydroxyl group is cross-linked. At least one hydroxyl group of a plurality of polymer substances has a heavy metal ion trapping site in the molecule and a compound having one boronate group and / or a phosphate ion trapping site in the molecule. Moreover, a polymer gel characterized in that the boronic acid group of a compound having one boronic acid group is bonded has been proposed.
Further, Patent Documents 2 and 3 propose cross-linking agents for PVA, respectively.

Japanese Unexamined Patent Publication No. 2012-46596 Japanese Unexamined Patent Publication No. 2012-184198 WO2014 / 199870

However, the composition using the cross-linking agent according to the above proposal still has a problem in terms of insolubilization and a problem in terms of storage stability. That is, if the composition is stored in a mixed state, the cross-linking reaction proceeds in a normal temperature environment, and there is a problem that the composition cannot be used as a film-forming composition.
In addition, when the storage stability is improved, there is a problem that the specification becomes complicated due to the increase in the process at the time of use, such as the addition of a special reagent, the addition of a heat treatment process, and the addition of a process for removing by-products. There was also.
Therefore, an object of the present invention is to provide a coating composition and a coating agent which are excellent in storage stability, can be used easily and easily, and can hydrophilize a solid surface with high performance.

As a result of diligent studies to solve the above problems, the present inventors have found that the storage stability is improved by adding diboronic acid as a cross-linking agent to PVA and water acting as a reaction competitor. The present invention has been completed by discovering and further studying.
That is, the present invention provides the following inventions.
1. 1. Polyvinyl alcohol, a polyfunctional group-containing compound having two or more functional groups capable of reacting with a hydroxyl group, water, and
A coating composition containing a volatile solvent.
2. 2. The mixing ratio of each ingredient is
The mixing ratio of the volatile solvent and the water is volatile solvent: water = 100: 25 to 450 (weight ratio).
The mixing ratio of the volatile solvent, the water, polyvinyl alcohol, and the polyfunctional group-containing compound is
The coating composition according to 1, wherein the volatile solvent and water: polyvinyl alcohol: a polyfunctional group-containing compound = 100: 0.1 to 5.0: 0.005 to 0.5 (weight ratio). ..
A coating agent using the coating composition described in 3.1.

The coating composition and coating agent of the present invention have excellent storage stability, can be used easily and easily, and can hydrophilize a solid surface with high performance.

FIG. 1 is a photograph (drawing substitute photograph) for confirming hydrophilicity with the coating agent obtained in Example 1, FIG. 1 (a) shows before coating, and FIG. 1 (b) shows after coating. FIG. 2 is a photograph (drawing substitute photograph) showing a state when the solution is allowed to stand for one day in a test for confirming the fluidity of the solution due to the addition of water in Example 7. FIG. 3 is a photograph (drawing substitute photograph) showing the state when the solution was allowed to stand for 7 days in the test for confirming the fluidity of the solution due to the addition of water in Example 7. FIG. 4 is a photograph (drawing substitute photograph) showing the state when the solution was allowed to stand for 31 days in the test for confirming the fluidity of the solution due to the addition of water in Example 7.

Hereinafter, the present invention will be described in more detail.
The coating composition of the present invention is characterized by containing polyvinyl alcohol (PVA), a polyfunctional group-containing compound having two or more functional groups capable of reacting with a hydroxyl group, water, and a volatile solvent.
It will be described in more detail below.

<Polyvinyl alcohol (PVA)>
The PVA used in the present invention can be used without particular limitation as long as it is usually used for hydrophilization of the solid surface, but in the present invention, PVA having a saponification degree of 40% to 100% is preferably used. Be done. If the saponification degree is less than 40%, sufficient hydrophilicity effect, protective property, and organic solvent resistance may not be obtained, so it is preferably within the above range.

<Multifunctional group-containing compound having two or more functional groups capable of reacting with a diol moiety and a boronic acid ester (hereinafter, simply referred to as "polyfunctional group-containing compound")>
The polyfunctional group-containing compound is not particularly limited as long as it is a compound having a plurality of functional groups capable of reacting with the hydroxyl group of PVA, and various compounds can be used, but a bifunctional compound having an aromatic skeleton is preferable. is there. Specific examples thereof include benzene-1,4-diboronic acid and benzene-1,3-diboronic acid (for example, a compound having 6 or less carbon atoms and having two boronic acid groups in the molecule). .. Further, benzene-1,3,5-triboronic acid and the like, which are trifunctional group compounds, can be mentioned as the polyfunctional group-containing compound.

<Water>
In the coating compositions of the present invention, water is added, but the presence of water is very important. Normally, when the above polyfunctional group-containing compound, for example, diboronic acid and PVA are mixed, water is generated as a by-product by the reaction between boronic acid and a hydroxyl group, but by allowing water to exist as a component in the composition from the beginning. , The reaction between the polyfunctional group-containing compound and the hydroxyl group of PVA is suppressed, and the storage stability of the coating composition of the present invention in the mixed system is improved.

<Volatile solvent>
As the volatile solvent, a solvent having a vapor pressure of 1 kPa or more at room temperature can be preferably used, and specific examples thereof include ethanol, methanol, and propanol.

<Quantity ratio>
As for the blending ratio of each component, the blending ratio of the volatile solvent and the water is preferably volatile solvent: water = 100: 20 to 450 (weight ratio). Further, the mixing ratio of the polyvinyl alcohol and the polyfunctional group-containing compound to the total amount of the volatile solvent and water is the water-containing volatile solvent: polyvinyl alcohol: polyfunctional group-containing compound = 100: 0.1 to 5. It is preferably 0.0: 0.005 to 0.5 (weight ratio), and more preferably 100: 0.5 to 4.0: 0.03 to 0.3 (weight ratio). The blending ratio of the volatile solvent in the entire composition is preferably 80% by weight or less, more preferably 60% by weight or less.
The mixing ratio of each ingredient is
The mixing ratio of the volatile solvent and the water is volatile solvent: water = 100: 25 to 450 (weight ratio).
The mixing ratio of the volatile solvent, the water, polyvinyl alcohol, and the polyfunctional group-containing compound is
The coating according to claim 1, wherein the volatile solvent and water: polyvinyl alcohol: a polyfunctional group-containing compound = 100: 0.5 to 4.0: 0.03 to 0.3 (weight ratio). Composition.
Storage stability is improved by setting the blending ratio of water within the above range, and handling of the composition and the coating agent of the present invention described later is easy by setting the blending ratio of the volatile solvent within the above range. Therefore, a simple and simple hydrophilization treatment of the solid surface becomes possible, and therefore, it is preferably within the above range.

<Other ingredients>
In the coating composition of the present invention, in addition to the above-mentioned components, an additive used for this kind of solid surface coating agent and a compound having one boronic acid group and a related group in the molecule are defined in the present invention. It can be used within a range that does not impair the desired effect.

<Usage / effect>
The coating composition of the present invention can be used by appropriately mixing to obtain a mixture, that is, the coating agent of the present invention.
The coating composition of the present invention can be stored for a long period of time even if all of them are mixed, and since boronic acids having a simple structure are used, raw materials are easily available, and it is necessary to protect functional groups with protecting groups. Since it does not exist, it can be used easily, it is easy to manufacture, and since no by-products are produced other than water, it can be used without considering the influence of by-products.
(Coating agent)
The coating agent of the present invention is formed by a mixture obtained by mixing the above-mentioned coating composition of the present invention. Therefore, the essential constituents are the same as the above-mentioned coating composition, and the blending ratio of each component is also the same.
The coating agent of the present invention can be obtained by mixing each component of the above-mentioned coating composition, but preferably PVA, water and a volatile solvent are mixed, and the obtained mixed solution and a large amount are used. It is preferably obtained by mixing with a solution of a functional group-containing compound. In addition, these mixing can be carried out at normal temperature and pressure.
The coating agent of the present invention can be used according to a conventional method, and has the same effect as that of the above-mentioned coating composition, but is preferably used as follows.
Since it has excellent storage stability, it can be stored as a paint for a long period of time, and it is not necessary to prepare a mixed solution each time it is applied, and a large area can be coated. Therefore, it can be applied by various methods such as spray method, casting method, dip method, stamp method, inkjet method, etc., and can be used for various materials (resin, glass, ceramic, metal, natural polymer (cellulose, etc.)). It can be applied to various shapes (plate, paper (fiber surface), non-woven fabric (nanofiber surface), tube (inside capillary), filter paper, glass filter paper, porous body).
The coating agent of the present invention having such an effect can be used as follows, and can be applied to each of the following applications.
Coating agent to prevent the adhesion of proteins and cells to biochemical equipment and medical equipment, coating agent for paper micro analysis chip, antifouling paint on ship bottom, cloudproof coating agent, antistatic coating agent, Coating agent for organic solvent resistant, paint for forming interface layer for chemically modifying functional molecules on solid surface (hereinafter referred to as application example), heterogeneous catalyst carrier, separator carrier, solid chemical sensor carrier (heavy metal ion detection) Etc.), Water pollutant adsorbent / Carrier for adsorbent for resource recovery

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

[Example 1] Preparation of coating film and PVA (saponification degree 80%, MW = 9,000 to 10,000) solution (PVA concentration 1.8% by weight, ethanol) of a mixed solvent of water resistant water and ethanol Concentration 49.2% by weight, water concentration 49.0% by weight) 100 parts by weight and ethanol solution of benzene-1,4-diboronic acid as a polyfunctional group-containing compound (benzene-1,4-diboronic acid concentration 0. 30 parts by weight (8% by weight) was mixed to obtain a mixture as the coating composition of the present invention (final concentration: ethanol concentration 51.3% by weight, water concentration 47.1% by weight, PVA concentration 1.4). %% by weight, 0.2% by weight of benzene-1,4-diboronic acid concentration, and the final concentration is the content of each component in the finally obtained coating composition expressed in% by weight).
Using this mixture as the coating agent of the present invention, the inner bottom surface of the polystyrene petri dish was coated. The following tests were conducted to form a crosslinked film and confirm the water resistance of the coating film. The results are shown below.
Coating conditions: The above mixture (2.4 mL) was poured into a polystyrene petri dish (9 cm in diameter) lower plate, dried in air at room temperature, and the membrane formed inside the bottom surface of the lower plate was thoroughly rinsed with water.
<Confirmation of crosslinked film formation>
Confirmation conditions for crosslinked film formation : The infrared absorption spectrum of the obtained film was measured by the total reflection method (ATR method).
Measurement Results: In the infrared absorption spectrum of a thin film, hydroxyl groups PVA has, carbonyl carbon - with the absorption peak of the stretching vibration of the oxygen bond is observed near 3400 cm ^-1 and 1700 cm ^-1 respectively, boron having boronic acid - oxygen The absorption peak of the expansion and contraction vibration of the bond was observed around 1300 cm ^-1 . In addition, an absorption peak characteristic of the boronic acid ester bond was observed near 660 cm- ¹ . This data indicates that the boronic acid group forms a boronic acid ester bond with the hydroxyl group of polyvinyl alcohol in the membrane.
<Confirmation of water resistance>
Confirmation condition of water resistance : Pour water (20 mL) into a polystyrene petri dish (diameter 9 cm) coated on the inside of the bottom surface of the lower plate, remove water after 12 hours, 24 hours, 48 hours and 72 hours soaking, and remove the film. By measuring the dry weight of the product, it was confirmed whether or not it was dissolved in water.
Measurement results : The dry weight of the membrane before and after immersion was 25.8 mg (before immersion), 26.0 mg (after 12 hours immersion), 26.2 mg (after 24 hours immersion), and 25.5 mg (after immersion), respectively. (After 48 hours of immersion) and 25.6 mg (after 72 hours of immersion), and no change was observed in the dry weight of the film even after 72 hours of immersion. Therefore, the obtained film was insoluble in water and had high water resistance. It was shown to have sex.

[Test Example 1] Hydrophilicity of coating film Various solid substrates were coated with the coating agent of the present invention obtained in Example 1. Polyethylene (PS), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polytetrafluoroethylene (PTEF), polyethylene terephthal as coating objects. Using a substrate of tarato (PET), aluminum (Al), copper (Cu), stainless steel SUS404 (SUS), silicon (Si), and glass (Glass) (all 50 mm long x 10 mm wide, 1 mm thick), the following Coating was performed under the conditions. The following tests were conducted to confirm the hydrophilicity. The results are shown below.
Coating conditions: A solid substrate composed of the above-mentioned objects was immersed in the above-mentioned coating agent of the present invention, then pulled up and dried in air at room temperature. The infrared absorption spectrum of the resulting samples was measured by ATR method, hydroxyl groups and carbonyl carbon of PVA - with the absorption peak of the stretching vibration of the oxygen bond is observed near 3400 cm ^-1 and 1700 cm ^-1 respectively, boronic acid A peak derived from the absorption of the expansion and contraction vibration of the boron-oxygen bond was observed around 1300 cm- ¹ . In addition, an absorption peak characteristic of the boronic acid ester bond was observed near 660 cm- ¹ . From the above, it can be seen that it is coated with polyvinyl alcohol crosslinked with benzene-1,4-diboronic acid.
Further, even after the obtained substrate was immersed in water, a peak derived from polyvinyl alcohol crosslinked with benzene-1,4-diboronic acid was confirmed in the infrared absorption spectrum of the obtained substrate. It can be seen that water resistance is imparted.
Conditions for hydrophilicity test: The contact angle of water dropped on the substrate was measured using a contact angle measuring device.
Results of hydrophilicity test: Photographs of water droplets dropped on the polystyrene substrate before coating (left) and after coating (right) are shown in FIG.
Table 1 shows the contact angles of water before and after coating on the solid substrate of each object.

From the above results, it can be seen that the contact angle of each coated solid substrate is 49 ± 9 degrees on average, which is a value indicating hydrophilicity. From this, it can be seen that the obtained film is hydrophilic and the coating agent of the present invention has a hydrophilic effect.

[Test Example 2] Storage stability of coating agent In order to confirm the storage stability of the coating agent obtained in Example 1, a storage stability test was conducted under the following conditions.
Conditions for storage stability test : The kinematic viscosity of the prepared mixture immediately after preparation and one month after preparation was measured using an Ostwald viscometer.
Results : No precipitation was observed in the mixture even 1 month after preparation. Further, the kinematic viscosity of the solution immediately after preparation is 4 cSt, and the kinematic viscosity after 1 month is also 4 cSt, and no change is observed in the viscosity of the mixture even after 1 month, indicating that the mixture has high storage stability. ..

[Test Example 3] Cloud-proof property of coating film Using the coating agent obtained in Example 1, a coating treatment was applied to the inside of an upper plate (lid) of a polystyrene petri dish (diameter 4 cm), and the following cloud-proof property test was performed. Was done.
Coating conditions : A coating agent (0.45 mL) was applied to the inside of an upper plate (lid) of a polystyrene petri dish (diameter 4 cm) and dried in air at room temperature. The obtained upper dish (lid) was rinsed with water to obtain an insoluble colorless transparent film in which polyvinyl alcohol was crosslinked with benzene-1,4-diboronic acid inside the upper dish (lid).
Conditions for cloud-proof test : When water at 40 ° C is poured into the lower plate of the polystyrene petri dish and the upper plate of the untreated polystyrene petri dish (lid) and the upper plate of the coated polystyrene petri dish are covered, respectively. The cloudiness inside the upper plate (lid) was judged by measuring the light transmittance.
Observation results : In the untreated Petri dish upper plate (lid), the inside was cloudy and the light transmittance decreased, but in the coated Petri dish upper plate (lid), the light transmittance decreased. No cloudiness was observed inside it. From this, it can be seen that the coating agent of the present invention has cloud-proof properties.

[Test Example 4] Organic solvent resistance of coating film Using the coating agent obtained in Example 1, a coating agent (0.45 mL) was applied to the upper surface of an upper plate (lid) of a polystyrene petri dish (diameter 4 cm). Dry in air at room temperature. The obtained upper dish (lid) was rinsed with water to obtain an insoluble colorless transparent film in which polyvinyl alcohol was crosslinked with benzene-1,4-diboronic acid on the upper surface of the lid. Then, the following resistance test was conducted.
Conditions for resistance test to organic solvent : Chloroform, dichloromethane, acetone, ethyl acetate, and tetrahydrofuran were added to the upper surfaces of the untreated polystyrene petri dish upper plate (lid) and the coated polystyrene petri dish upper plate (lid). 15 mL was added dropwise, and the sample was observed and the light transmittance was measured after the solvent was evaporated.
Observation results : In the untreated polystyrene petri dish, whitening of the upper surface of the upper plate (lid) due to dissolution of polystyrene was observed during the drying process of acetone, which is an organic solvent, and a significant decrease in light transmittance was observed. On the other hand, in the coated polystyrene petri dish upper plate (lid), no whitening was observed and no decrease in light transmittance was observed even after the acetone was dried, so that the transparency of polystyrene was maintained. Was shown to be. Even when the above-mentioned other organic solvent was used, whitening was not observed in the coated polystyrene petri dish upper plate (lid), so that the coating film produced by using the coating agent of the present invention was obtained. It can be seen that it has high resistance to organic solvents.

[Test Example 5] Protein adsorption inhibitory property of coating film Using the coating agent obtained in Example 1, the same polystyrene (PS) substrate used in Test Example 1 was coated under the following conditions. It was. Then, as confirmation of antifouling property, the following test using bovine serum albumin (BSA), which is a protein, was performed. The results are shown below.
Coating conditions : The PS substrate was immersed in the above coating agent, taken out, and dried in air at room temperature to obtain an insoluble colorless transparent film in which polyvinyl alcohol was crosslinked with benzene-1,4-diboronic acid.
Conditions for protein adsorption test : The untreated polystyrene substrate and the coated substrate were immersed in bovine serum albumin (BSA) phosphate buffer (pH: 7.4, BSA: 1 mg / mL) at room temperature, respectively. .. After 24 hours, the sample was removed, rinsed with water and dried at room temperature. The obtained substrate was analyzed by X-ray photoelectron spectroscopy, and the presence or absence of BSA adsorbed on the substrate was investigated by detecting photoelectrons derived from nitrogen atoms.
Results of protein adsorption test : In the untreated polystyrene substrate, a signal derived from photoelectrons from the 1s orbital of the nitrogen atom was observed near 398 eV. On the other hand, in the polystyrene substrate subjected to the coating treatment, no peak was confirmed in the vicinity of 398 eV. This indicates that the signal derived from nitrogen atoms confirmed on the untreated polystyrene substrate is derived from BSA adsorbed on the substrate surface, and that BSA is not adsorbed on the coated polystyrene substrate. Shown. From this, it can be seen that the coating film produced from the coating agent of the present invention has antifouling properties.
[Test Example 6] Cell Adsorption Inhibition Characteristics of Coating Film Using the coating agent obtained in Example 1, a polystyrene (PS) 24-well well was coated under the following conditions. Then, as confirmation of antifouling property, the following adsorption test using HeLa cells was performed. The results are shown below.
Coating conditions : A coating agent (10 microliters) was dispensed into each hole of the 24-well well. After air-drying, the well was rinsed with phosphate buffer (PBS) to obtain an insoluble colorless transparent film in which polyvinyl alcohol was crosslinked with benzene-1,4-diboronic acid on the bottom surface of the well.
Conditions for cell adsorption test : HeLa cells were seeded in untreated wells and coated wells, cell medium (D-10) was added, and the cells were cultured for 24 hours. The inside of the well was observed under a microscope, and the cells in the well were judged to be alive or dead by trypan blue staining.
Results of cell adsorption test : In the untreated polystyrene substrate after culturing for 24 hours, it was confirmed by microscopic observation that the cells adhered and adhered to the bottom surface of the well, and no floating cells were observed. On the other hand, in the coated well, no adhesion of cells to the bottom surface of the well was observed, and the cells were floating. Also, seeded HeLa cells in wells coated treatment (cell viability: 87%, number of ^{cells: 1.07 × 10 6 cells / mL} ), the suspension cells observed after 24 hours, by trypan blue staining was subjected to determining the viability of the cells, the cell viability (87 ± 5)%, the cell number became ^{(1.80 ± 0.05) × 10 6} cells / mL. The viability of the cells cultured in the coated wells did not change from the viability before seeding, and the number of cells after culture was higher than the number of seeded cells. From these results, it can be seen that the coating film formed by using the coating agent of the present invention has extremely low cell adsorption characteristics and high biocompatibility.

[Test Example 7] Chemical modification of the surface of the coating film Using the coating agent obtained in Example 1, the following polyethylene substrate (white: vertical 50 mm × horizontal 10 mm, thickness 1 mm) used in Test Example 1 was used. Coating treatment was applied under the conditions.
Coating conditions : The substrate was immersed in the above mixture, taken out, and dried in air at room temperature to obtain a colorless and transparent film insoluble in water in which polyvinyl alcohol was crosslinked with benzene-1,4-diboronic acid.
Conditions for chemical modification experiment : Immerse the coated substrate in an ethanol solution (0.1 mM) containing a borondipyrromethene dye having a phenylboronic acid group represented by the following formula (I) as an anchor site as a chemical modification agent at room temperature. did. After immersion, the substrate was removed from the solution and rinsed with ethanol. As a control experiment, a similar experiment was carried out using a borondivirometen dye (represented in formula (II)) having no boronic acid group.
Results of chemical modification experiment : The substrate immersed in the ethanol solution of borondipyrromethene dye having a boronic acid group as an anchor site exhibited an orange color derived from the dye. On the other hand, no coloration was observed on the substrate immersed in the borondipyrromethene dye ethanol solution having no boronic acid group, and the substrate remained white. This indicates that the PVA constituting the coating film and the boronic acid group of the borondipyrromethene dye used as the chemical modifier are bonded via a boronic acid ester bond, and the boronic acid group is bonded. It can be seen that the substrate coated with the coating agent of the present invention can be easily chemically modified under mild conditions by using the compound as a chemical modifier.
In addition, a compound in which a boronic acid group is introduced into a fluorescent coumarin dye shown in Reference Synthesis Example 1 and Formula (III) below, or a compound in which a boronic acid group is introduced into an azo dye having a specific color responsiveness to heavy metal ions. Similarly, when (shown in the formula (v)) is used in place of the borondipyrromethene dye, the chemical modification can be easily performed, and the chemically modified substrate is derived from the fluorescent dye derived from coumarin and the dye derived from the azo dye, respectively. It showed a specific color response to metal ions.

[Reference composition example]
Synthesis of Fluorescent Coumarin Dye with Boronic Acid Group

Under a nitrogen atmosphere, add 3-aminophenylboronic acid (0.16 g, 1.17 mmol) and 7- (diethylamino) coumarin-3-carboxylic acid (0.30 g, 1.15 mmol) to dehydrated dichloromethane (20 mL) and bathe the solution in an ice bath. Cooled with. To this solution is added 1- [bis (dimethylamino) methylene] -1H-benzotriazolium 3-oxide hexafluorophosphate (HBTU, 0.46 g, 1.20 mmol) and diisopropylethylamine (DIPEA, 0.19 g, 1.5 mmol). , Stirred at room temperature. After 12 hours, dichloromethane (200 mL) was added to the reaction solution, the mixture was washed with saturated aqueous ammonium chloride solution (150 mL), and the organic layer was dehydrated with sodium sulfate. The resulting yellow solution was concentrated on a rotary evaporator and the resulting precipitate was collected by filtration to give the desired product as a yellow solid. (Yield 0.23 g, Yield 57%)
Spectral data: ¹ H NMR (500 MHz, DMSO-d ₆ ): δ (ppm) = 1.16 (t, 6H, J = 7.0 Hz), 3.51 (q, 4H, J = 7.0 Hz), 6.69 (d, 1H) , J = 2.2 Hz), 6.86 (dd, 1H, J = 2.4 and 9.1 Hz), 7.34 (dd, 1H, J = 7.7 and 7.7 Hz), 7.53 (d, 1H, J = 7.4 Hz), 7.75 (d , 1H, J = 9.1 Hz), 7.83 (s, 1H), 7.99 (d, 1H, J = 9.3 Hz), 7.83 (s, 1H), 8.10 (s, 2H), 8.78 (s, 1H), 10.76 (s, 1H); ¹³ C NMR (125 MHz, DMSO-d ₆ ): δ (ppm) = 12.2, 44.3, 95.8, 107.8, 109.0, 110.3, 119.6, 123.7, 128.9, 131.8, 138.2, 148.1, 152.7, 157.3, 160.6, 162.1; HRMS (ESI): m / z [M + H] ⁺ calcd. For C ₂₀ H ₂₂ BN ₂ O ₅ , 381.1620; found, 381.1621.

Synthesis of coumarin dye used as a reference compound according to the following reaction formula

Aniline (0.05 g, 0.55 mmol), 7- (diethylamino) coumarin-3-carboxylic acid (0.15 g, 0.57 mmol), 1- [bis (dimethylamino) methylene] -1H-benzotriazolium 3 in a nitrogen atmosphere -Oxidehexafluorophosphate (HBTU, 0.23 g, 0.61 mmol) and diisopropylethylamine (DIPEA, 0.05 g, 0.40 mmol) were added to dehydrated dimethylformamide (10 mL). The resulting yellow solution was stirred at room temperature. After 12 hours, the yellow reaction solution was poured into water (100 mL) and the precipitated solid was collected by filtration. The resulting solid was washed with 1% aqueous sodium carbonate solution and water to give a yellow solid. (Yield 0.14 g, Yield 76%)
¹ H NMR (500 MHz, DMSO-d ₆ ): δ (ppm) = 1.16 (t, 6H, J = 7.0 Hz), 3.51 (q, 4H, J = 7.0 Hz), 6.68 (d, 1H, J = 1.8 Hz), 6.85 (dd, 1H, J = 2.0 and 9.0 Hz), 7.11 (t, 1H, J = 7.3 Hz), 7.37 (dd, 1H, J = 7.8 and 7.8 Hz), 7.71 (d, 2H, J = 8.3 Hz), 7.74 (d, 1H, J = 9.0 Hz), 8.77 (s, 1H), 10.74 (s, 1H); ¹³ C NMR (125 MHz, DMSO-d ₆ ): δ (ppm) = 12.3, 54.9, 95.9, 107.9, 109.1, 110.4, 121.4, 125.4, 128.1, 129.7, 131.8, 135.1, 137.5, 148.1, 152.8, 157.4, 160.5, 162.4; ¹¹ B NMR (160 MHz, DMSO-d ₆ ): δ (ppm) = 28.1; HRMS (ESI): m / z [M + Na] ⁺ calcd. For C ₂₀ H ₂₀ N ₂ O ₃ Na, 359.1366; found, 359.1364.

Synthesis of a chemical modifier in which a boronic acid group is introduced into an azo dye showing colorimetric response to heavy metal ions according to the following reaction formula.

In a nitrogen atmosphere, pyridylazoresorcin (0.20 g, 0.94 mmol), 3-bromomethylphenylboronic acid (0.20 g, 0.93 mmol) and sodium hydrogen carbonate (0.39 g, 4.7 mmol) were added to dehydrated dimethylformamide (10 mL). Stirred at room temperature for 3 days. After confirming the progress of the reaction, dimethylformamide was distilled off under reduced pressure. The obtained solid was added to a mixed solvent of tetrahydrofuran and dichloromethane, and then washed with a sodium chloride aqueous solution by a liquid separation operation. The resulting organic phase was dried over sodium sulfate and the solvent was evaporated to give a solid. The obtained solid was purified by column chromatography (normal phase silica gel, dichloromethane / methanol = 49/1 (v / v)) to obtain a red solid. (Yield 0.04 g, Yield 12%)
Spectral data: ¹ H NMR (500 MHz, DMSO-d ₆ ): δ (ppm) = 5.21 (s, 2H), 6.71 (dd, 1H, J = 2.6 and 9.2 Hz), 7.39 (t, 1H, J = 7.5 Hz), 7.45 (ddd, 1H, J = 1.0, 4.9 and 7.4 Hz), 7.51 (d, 1H, J = 7.7 Hz), 7.66 (d, 1H, J = 9.2 Hz), 7.78 (d, 1H, J = 7.4 Hz), 7.84 (d, 1H, J = 8.2 Hz), 7.88 (s, 1H), 8.00 (td, 1H, J = 1.8 and 7.8 Hz), 8.10 (d, 2H, J = 5.6), 8.61 (dd, 1H, J = 1.0 amd 4.8 Hz), 13.65 (s, 1H); ¹³ C NMR (125 MHz, DMSO-d ₆ ): δ (ppm) = 70.6, 102.9, 111.5, 112.6, 124.4, 124.4 , 127.8, 130.0, 130.1, 133.4, 133.9, 134.1, 135.1, 139.2, 149.3, 160.0, 162.8, 165.3; HRMS (ESI): m / z [M + H] ⁺ calcd. For C ₁₈ H ₁₇ BN ₃ O ₄ , 350.1310; found, 350.1307.

[Test Example 8] Coating of glass filter paper Using the coating agent obtained in Example 1, a glass filter paper (21 mm diameter, trade name "glass filter paper" manufactured by Advantech Co., Ltd.) was coated under the following conditions.
Coating conditions : Glass filter paper (21 mm diameter) was immersed in a coating agent. After 30 seconds, the glass filter paper was removed from the coating agent, and the excess coating agent was sucked from the glass filter paper using a cellulosic filter paper.
Coating Results : Scanning electron microscopy measurements of the coated and untreated glass filter papers showed no difference in the morphology of the fiber structures that make up the glass filter paper. On the other hand, when the infrared absorption spectra of the coated glass filter paper and the untreated glass filter paper were measured by the total internal reflection method (ATR method), the hydroxyl group derived from PVA was measured in the infrared absorption spectrum of the coated glass filter paper. the carbonyl carbon - with the absorption peak of the stretching vibration of the oxygen bond is observed near 3400 cm ^-1 and 1700 cm ^-1 respectively, boron acid in the vicinity of 1300 cm ^-1 - peak derived from stretching vibration absorption of oxygen bond observed Was done. In addition, an absorption peak characteristic of the boronic acid ester bond was observed near 660 cm- ¹ . From the above, it was shown that the glass filter paper was coated with polyvinyl alcohol crosslinked with benzene-1,4-diboronic acid.
Chemical modification of coated glass filter paper : In order to obtain confirmation that the coated glass filter paper is coated with PVA, an azo dye having a boronate group shown in the following formula as an anchor site is used as a chemical modification agent. Then, the coated glass filter paper was chemically modified. In addition, as a control experiment, a similar experiment was performed using untreated glass filter paper.

Chemical structure of azo dye having a boronic acid group as an anchor site

Conditions for chemical modification : The coated glass filter paper and the untreated glass filter paper were immersed in an ethanol solution (0.1 mM) of an azo dye having a phenylboronic acid group as an anchor site at room temperature. The glass filter paper was removed from the solution and rinsed with methanol for chemical modification.
Results of Chemical Modification Experiment : The glass filter paper coated with the coating agent of the present invention exhibited a yellow color derived from the azo dye. On the other hand, no coloration was observed when untreated glass filter paper was used. From this, it can be seen that the surface of the glass filter paper can be easily chemically modified by using the coating agent obtained in Example 1 and the compound having a phenylboronic acid group as the chemical modification agent.

[Example 2] Preparation of a coating film using saponified 88% PVA and as a water resistant PVA, a PVA (saponification degree 88%, MW = 146,000 to 186,000) solution (PVA concentration 1.8 weight) The coating composition of the present invention was obtained in the same manner as in Example 1 except that the blending amount of each component was adjusted so as to obtain the following final concentration conditions using%.
Final concentration conditions (indicated by the content ratio of each component) : Ethanol concentration 51.4% by weight, water concentration 47.2% by weight, PVA concentration 1.32% by weight, benzene-1,4-diboronic acid concentration 0.05% by weight %.
Using the obtained coating agent of the present invention, coating was performed under the following coating conditions on the inside of the bottom surface of the polystyrene petri dish. Next, the following tests were conducted to confirm the water resistance of the coating film. The results are shown below.
Coating conditions : The above mixture (2.4 mL) was poured into a lower plate of a polystyrene petri dish (diameter 9 cm) and dried in air at room temperature. A colorless and transparent film was obtained by pouring water (20 mL) into a coated petri dish and allowing it to stand at room temperature for 30 minutes to wash the film. Total reflection method infrared absorption spectrum of the film obtained was measured by (ATR method), hydroxyl groups and carbonyl carbon derived from PVA - absorption peak stretching vibration of oxygen bond in the vicinity of 3400 cm ^-1 and 1700 cm ^-1, respectively while being observed, boron acid in the vicinity of 1300 cm ^-1 - are observed peaks derived from stretching vibration absorption of oxygen binding, characteristic absorption peaks in the boronic acid ester bond was observed near 660 cm ^-1. The results of the obtained infrared absorption spectrum show that polyvinyl alcohol is crosslinked with benzene-1,4-diboronic acid in the obtained membrane.
<Confirmation of water resistance>
Confirmation condition of water resistance : After pouring water (20 mL) into the polystyrene petri dish (diameter 9 cm) obtained above and coating the bottom surface inside the lower plate, after 12 hours, 24 hours, 48 hours and 72 hours of immersion. The presence or absence of dissolution was confirmed by measuring the dry weight of the membrane after removing water.
Measurement results : The dry weight of the membrane after immersion was 19.5 mg (after 12 hours immersion), 19.6 mg (after 24 hours immersion), 19.1 mg (after 48 hours immersion) and 19.3, respectively. It was mg (after immersion for 72 hours). Since no change was observed in the dry weight, it was found that a film having high water resistance can be obtained by the treatment with the coating agent of the present invention.

[Example 3] Preparation of a coating film using 99% saponified PVA and as a water resistant PVA, a PVA (saponification degree 99%, MW = 89,000-98,000) solution (PVA concentration 1.6 weight) %) Was used to obtain the coating composition of the invention obtained in the same manner as in Example 1 except that the blending amount of each component was adjusted so as to obtain the following final concentration conditions.
Final concentration conditions : ethanol concentration 20.6% by weight, water concentration 78.2% by weight, PVA concentration 1.25% by weight, benzene-1,4-diboronic acid concentration 0.04% by weight.
The test was carried out in the same manner as in Example 2 using the obtained coating agent of the present invention (2.4 mL). The results are shown below.
Measurement results : The dry weight of the membrane after immersion was 16.8 mg (after 12 hours immersion), 17.1 mg (after 24 hours immersion), 16.3 mg (after 48 hours immersion) and 16.4, respectively. It was mg (after immersion for 72 hours). Since no change was observed in the dry weight, it was found that a film having high water resistance could be obtained.

[Example 4] Preparation of coating film using 40% saponified PVA and as a water resistant PVA, a PVA (saponification degree 40%, MW = 72,000) solution (PVA concentration 3.9% by weight) was used. The coating composition of the present invention was obtained in the same manner as in Example 1 except that the blending amount of each component was adjusted so as to have the following final concentration conditions.
Final concentration conditions: ethanol concentration 73.7% by weight, water concentration 23.3% by weight, PVA concentration 2.9% by weight, benzene-1,4-diboronic acid concentration 0.1% by weight.
The test was carried out in the same manner as in Example 2 using the obtained coating agent of the present invention (2.4 mL). The results are shown below.
Measurement results : The dry weight of the membrane before and after immersion was 41.0 mg (before immersion), 41.0 mg (after 12 hours immersion), 41.0 mg (after 24 hours immersion), and 40.4 mg (after immersion). (After 48 hours of immersion) and 40.9 mg (after 72 hours of immersion), and no change was observed in the dry weight even after 72 hours, so the obtained membrane was insoluble in water and had high water resistance. It was shown to have.

[Example 5] Preparation of coating agent using benzene-1,3-diboronic acid as a "polyfunctional group-containing compound" PVA (ethanol concentration 49% by weight, water concentration 49% by weight) of a mixed solvent of water and ethanol 80% saponification) solution (PVA concentration 2% by weight) 100 parts by weight and ethanol solution (benzene-1,3-diboronic acid concentration 0) of benzene-1,3-diboronic acid (commercially available) as a polyfunctional group-containing compound .8% by weight) 30 parts by weight was mixed to obtain the coating composition of the present invention (final concentration conditions: ethanol concentration 51.3% by weight, water concentration 47.1% by weight, PVA concentration 1.4% by weight). %, benzene-1,3-diboronic acid concentration 0.2% by weight).
By using the obtained coating agent of the present invention by the same preparation method as in Example 1, a colorless transparent film in which polyvinyl alcohol was crosslinked with benzene-1,3-diboronic acid was obtained. The membrane produced showed high stability to water.

[Example 6] Preparation of a coating agent using benzene-1,3,5-triboronic acid as a "polyfunctional group-containing compound" A mixed solvent of water and ethanol (ethanol concentration 49% by weight, water concentration 49% by weight) Ethanol of 100 parts by weight of PVA (saponification 80% MW = 90,000 to 100,000) solution (PVA concentration 2% by weight) and benzene-1,3,5-triboronic acid as a polyfunctional group-containing compound The coating composition of the present invention was obtained by mixing with 100 parts by weight of a solution (benzene-1,3,5-triboronic acid concentration 0.7% by weight).
Final concentration conditions : ethanol concentration 51.4% by weight, water concentration 47.1% by weight, PVA concentration 1.35% by weight, benzene-1,3,5-triboronic acid concentration 0.16% by weight
Using the obtained coating agent of the present invention, a colorless transparent film in which polyvinyl alcohol was crosslinked with benzene-1,3,5-triboronic acid was obtained by the same preparation method as in Example 1. The membrane produced showed high stability to water.

[Example 7] Test on improvement of storage stability of coating agent by addition of water PVA (saponification degree 80%, MW = 9,000 to 10,000) and benzene-1, which are mixed solvents of water and ethanol. In a solution consisting of 4-diboronic acid, the storage stability of the solution as a coating agent was investigated by examining the fluidity of the solution obtained when the composition ratio of water and ethanol was changed. PVA concentration 1.1% by volume and benzene-1,4-diboronic acid concentration 1.7% by volume of mixed solvent with water to ethanol volume ratios of 5:95, 10:90, 20:80 and 40:60. The solution (1 mL) was prepared in a glass sample bottle (outer diameter 15 mm, height 35 mm, volume 2 mL), the sample bottle was covered with a poly stopper, and the mixture was allowed to stand at room temperature. The fluidity of the solution was confirmed by turning the sample upside down after 1, 7, and 31 days. In this test, when the sample was turned upside down, it was judged that the solution lost its fluidity when the solution did not fall.
It is shown in FIGS. 2, 3 and 4, respectively, after 1 day, 7 days, and 31 days. Further, in FIGS. 2 to 4, from the left, the PVA concentration of the mixed solvent having a volume ratio of water to ethanol of 5:95, 10:90, 20:80 and 40:60 is 1.1 by volume and benzene-1,4. -The state of a solution (1 mL) having a diboronic acid concentration of 1.7% by volume is shown.
As shown in FIG. 2, after one day, the solution of the mixed solvent having a volume ratio of water to ethanol of 5:95 loses fluidity, and the volume ratio of water to ethanol is 10:90, 20:80 and 40:60. The mixed solvent solution maintained its fluidity. As shown in FIG. 3, after 7 days, in addition to the solution of the mixed solvent having a volume ratio of water and ethanol of 5:95, the solution of the mixed solvent having a volume ratio of water to ethanol of 10:90 lost its fluidity. The mixed solvent solution with a volume ratio of water to ethanol of 20:80 and 40:60 maintained fluidity. As shown in FIG. 4, after 31 days, the solution of the mixed solvent having a volume ratio of water to ethanol of 20:80 and 40:60 maintained the fluidity. The above results show that by adding water to the solution containing PVA and a boronic acid-based cross-linking agent, the formation of boronic acid ester bonds in the solution is suppressed, and as a result, the storage stability of the coating agent is improved. Indicates to do.

Claims (3)

Polyvinyl alcohol, a polyfunctional group-containing compound having two or more functional groups capable of reacting with a hydroxyl group, water, and
A coating composition containing a volatile solvent. The mixing ratio of each ingredient is
The mixing ratio of the volatile solvent and the water is volatile solvent: water = 100: 25 to 400 (weight ratio).
The mixing ratio of the volatile solvent, the water, polyvinyl alcohol, and the polyfunctional group-containing compound is
The coating according to claim 1, wherein the volatile solvent and water: polyvinyl alcohol: a polyfunctional group-containing compound = 100: 0.1 to 5.0: 0.005 to 0.5 (weight ratio). Composition. A coating agent using the coating composition according to claim 1.