JP2021095475A - Antifreezing coated film material, coating method using the same, and application of the same - Google Patents

Abstract

To provide an antifreezing coated film material that enables formation of a coated film having an excellent antifreezing effect, a coating method using the same, and application of the same.SOLUTION: An antifreezing coated film material contains inorganic particles and an amphoteric ion resin composed of a copolymerization polymer of at least one anionic monomer and at least one cationic monomer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a freeze-suppressing coating material, a coating method using the same, and its use. More specifically, the present invention relates to a freeze-suppressing coating material capable of forming a coating film having an excellent anti-freezing effect, a coating method using the same, and its use.

For structures exposed to the natural environment, devices that are repeatedly heated and cooled, and the members that compose them, dew condensation and freezing may occur on their surfaces due to changes in the surrounding environmental conditions, causing various harmful effects. is there.
For example, when a fin-type heat exchanger that exchanges heat via multiple fins is used in a cold environment, frost (frozen condensed water) adheres to the surface of the fins and the fins are blocked. There is. In the fin type heat exchanger in which the fins are blocked by frost in this way, the heat exchange efficiency is lowered, so that defrosting work is required.
Therefore, as a countermeasure, a paint for suppressing frost formation may be applied to the fins of the fin type heat exchanger, and various paints and their materials have been proposed.

For example, Japanese Patent Application Laid-Open No. 2016-521568 (Patent Document 1) describes plant cells, plant organs, or plant tissues in a porous silica matrix, although the technical field is different from that of the present invention and the subject of freeze suppression is also different. In the method of encapsulating and cryopreserving in a porous silica matrix, a cryoprotectant (antifreeze agent) selected from dimethyl sulfoxide, saccharides, amino acids, amphoteric ionic compounds (betaine), glycols, polyols and mixtures thereof is formed into a porous silica matrix. The technique of carrying is disclosed.

Special Table 2016-521568

However, in the prior art including Patent Document 1, further improvement of the antifreezing effect is required.
Therefore, it is an object of the present invention to provide a freeze-suppressing coating material capable of forming a coating film having an excellent freeze-suppressing effect, a coating method using the same, and its use.

As a result of diligent studies to solve the above problems, the present inventors have applied a mixture of inorganic particles and a specific amphoteric ion resin to the base material to generate condensed water on the surface of the base material. We have found that the freezing temperature can be lowered to suppress freezing, and have completed the present invention.

Thus, according to the present invention, a freeze-suppressing coating film comprising inorganic particles and a zwitterionic resin composed of a copolymerized polymer of at least one anionic monomer and at least one cationic monomer. The material is provided.

Further, according to the present invention, there is provided a coating method including a coating step of coating the above-mentioned freeze-suppressing coating material on a substrate.

Further, according to the present invention, there is provided a fin material coated with the above-mentioned antifreezing coating material.

The present invention can provide a freeze-suppressing coating material capable of forming a coating film having an excellent freeze-suppressing effect, a coating method using the same, and its use.

The freeze-suppressing coating material of the present invention more exerts the above-mentioned effect when at least one of the following conditions (1) to (8) is satisfied.
(1) A resin other than the zwitterionic resin is further contained as a base resin.
(2) The base resin is a nonionic resin selected from polyvinyl alcohol and polyvinylpyrrolidone.
(3) The inorganic particles are silica particles or aluminum oxide particles.
(4) The inorganic particles are spherical inorganic particles having an average particle size of 5 nm or more and 100 nm or less, or needle-shaped inorganic particles having an average major axis of 100 nm or more and 4,000 nm or less and an average minor axis of 0.5 nm or more and 20 nm or less.
(5) The zwitterionic resin has a mass average molecular weight of 10,000 or more and 1,500,000 or less.
(6) The zwitterionic resin has a nonionic group.
(7) The nonionic group is an amide group.
(8) The zwitterionic resin contains cations and anions at a ratio of 1/9 to 9/1.

The coating method of the present invention more exerts the above-mentioned effect when at least the following condition (9) is satisfied.
(9) Prior to the coating step, a pretreatment step of subjecting the substrate to a degreasing treatment or a chemical conversion treatment is further included.

It is a schematic diagram which shows one form of the freeze-suppressing coating film material of this invention.

(1) Antifreeze coating material The antifreeze coating material of the present invention contains inorganic particles and a zwitterionic resin composed of a copolymer polymer of at least one anionic monomer and at least one cationic monomer. It is characterized by doing.
The present invention is not limited to the following description, and can be carried out with appropriate modifications within the scope of the object of the present invention.
Unless otherwise specified, each of the materials described below may be used alone or in combination of two or more.

The antifreeze coating material of the present invention exhibits the same antifreeze effect as known antifreeze proteins.
The reason can be inferred as follows.
In the molecule of the amphoteric ion resin, + ions and-ions associate to form a strong and constant structure (ion complex) in water, and the coating film of the antifreeze coating film material of the present invention is like an aluminum plate. When formed on a solid substrate (for example, dip), the ion complex forms a coating film while retaining its structure, and a part of the ion complex is retained on the film surface. The ion complex has irregularities on its surface, the concave portions trap ice nuclei and suppress nuclear growth, and the convex portions destroy minute ice nuclei to suppress nuclear formation. On the other hand, some + or-ions do not meet and function as ionics that attract water, so that the same antifreeze effect as polyamines is maintained.
Further, as will be described later, when the zwitterionic resin has a nonionic group such as an amide group, the association is relaxed, the size of the structure is optimized, and the antifreezing effect is promoted.
Further, the freeze-suppressing coating material of the present invention has high thermal stability and is suitable when it is necessary to bake the coating film formed on the substrate. On the other hand, the conventional antifreeze protein is a natural product and therefore has weak thermal stability, and is not suitable when the coating film needs to be baked.
Further, the freeze-suppressing coating material of the present invention can obtain a high freeze-suppressing effect by controlling the concentration of zwitterions, as will be described later.

FIG. 1 is a schematic view showing one form of the freeze-suppressing coating film material of the present invention.
In the figure, 1 is a zwitterionic resin, 2 is an inorganic resin particle, 3 is a base resin having an arbitrary composition, and 4 is a base material to be coated with a freeze-suppressing coating material.

(1-1) Inorganic particles Inorganic particles have the function of improving (strengthening) the durability of the coating film of the antifreezing coating film material, and freeze by making the surface of the coating film uneven to make it easier for water to get wet and to suppress dew condensation. It has a function of enhancing the inhibitory effect and may be either anionic or cationic.
Examples of the inorganic particles include metal particles, metal oxide particles and silica (SiO ₂ ) particles.
Examples of the metal of the metal particles include gold, platinum, silver, copper, iron, titanium, manganese, nickel, tin, aluminum and alloys containing these.
Further, as the metal oxide of the metal oxide particles, metal oxides exemplified as the metal of the metal particles, for example, aluminum oxide (Al ₂ O ₃ , alumina), titanium _{oxide (TIO 2} ), zinc oxide (ZnO). , Iron oxide (Fe ₂ O ₃ ), copper oxide (CuO) and the like.
Examples of the silica particles include colloidal silica.
Among these inorganic particles, silica particles and aluminum oxide particles are preferable, and their combined use is more preferable.

The shape of the inorganic particles is not particularly limited as long as the effect of the present invention is not impaired, but spherical and acicular particles are preferable, and as the inorganic particles, spherical inorganic particles and acicular inorganic particles are more preferable, and spherical silica particles and acicular oxidation. Aluminum particles are particularly preferred.

The spherical inorganic particles preferably have an average particle size of 5 nm or more and 100 nm or less.
By setting the average particle size of the spherical inorganic particles to 5 nm or more, the dispersibility of the spherical inorganic particles in the formed coating film can be improved. On the other hand, by setting the average particle size of the spherical inorganic particles to 100 nm or less, the film forming property of the coating film can be improved.
The average particle size of the more preferable spherical inorganic particles is 10 nm or more and 50 nm or less.

The needle-shaped inorganic particles preferably have an average major axis of 100 nm or more and 4,000 nm or less and an average minor axis of 0.5 nm or more and 20 nm or less.
By setting the average major axis of the acicular inorganic particles to 100 nm or more and the average minor axis to 0.5 nm or more, the dispersibility of the acicular inorganic particles in the coating film can be improved. On the other hand, by setting the average major axis of the needle-shaped inorganic particles to 4,000 nm or less and the average minor axis to 20 nm or less, the film forming property of the coating film can be improved.
More preferable needle-shaped inorganic particles have an average major axis and an average minor axis of 1,000 nm or more and 1,800 nm or less and 2 nm or more and 10 nm or less, respectively.

The "average particle size", "average major axis" and "average minor axis" of the inorganic particles can be measured by the following methods.
Under an electron microscope, arbitrarily select 20 particles from the inorganic particles to be measured, and the selected 20 particles have a "particle size (specifically, a circle-equivalent diameter)", a "major diameter", or a "minor diameter". "Is measured respectively. Calculate the arithmetic mean value of the obtained individual measured values "particle size", "major axis" or "minor axis", and use the obtained arithmetic mean value as the "average particle size" and "average" of the inorganic particles to be measured. It shall be "major axis" or "average minor axis".

The inorganic particles may be surface-treated with a surface treatment agent.
Examples of the surface treatment agent include a silane coupling agent, a titanium coupling agent, a silicone oil, and the like.
It is preferable that the surface of the inorganic particles is imparted with cationism by surface treatment.
Like the cationic resin, the inorganic particles to which the surface is provided with cationic properties can inhibit the regular arrangement of water molecules contained in the water adhering to the surface of the coating film to further improve the antifreeze effect. it can.

The mixing ratio of the inorganic particles in terms of solid content is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and particularly preferably 65% by mass or more and 85% by mass or less.
By setting the blending ratio of the inorganic particles in terms of solid content to 50% by mass or more, the freeze-suppressing effect of the formed coating film can be further improved. On the other hand, by setting the blending ratio of the inorganic particles in terms of solid content to 95% by mass or less, the film forming property of the coating film can be improved.

(1-2) Zwitterionic Resin The zwitterionic resin is composed of a copolymerized polymer of at least one anionic monomer and at least one cationic monomer.
The zwitterionic resin is a resin containing a positive charge (+ charge) and a negative charge (-charge) in the same resin, and is a zwitterionic compound (betaine) as described in the prior art (Patent Document 1). It does not contain natural polymers such as polylysine.
Here, betaine has a positive charge and a negative charge at non-adjacent positions in the same molecule, and a dissociable hydrogen atom is not bonded to the atom having the positive charge (quaternary ammonium, sulfonium, etc.). It is a general term for compounds (intramolecular salts) that do not have an electric charge as a whole molecule (which has a cationic structure such as phosphonium), and because the molecule as a whole has no electric charge, it is similar to nonionic polyvinyl alcohol. Further, it is presumed that intramolecular association does not occur in water like the amphoteric ion resin which is an essential component of the present invention.
In addition, in this specification, acrylic and methacryl may be generically referred to as "(meth) acrylic".

(1-2-1) Anionic Monomer Examples of the anionic monomer include a monomer containing a carboxyl group, a phosphoric acid group, a sulfonic acid group, and the like.
Specific examples of anionic monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, 2-methacryloyloxyethyl succinic acid and their sodium salts, potassium salts, ammonium salts, and 2-. Examples thereof include acroyloxyethyl acid phosphate, 2-methacloyloxyethyl acid phosphate, vinyl sulfonic acid and the like. Among these, monomers having a carboxyl group (carboxylic acids) are preferable, and acrylic acid is preferable.

(1-2-2) Cationic Monomer As the cationic monomer, a monomer having an amino group, an acid neutralized product of the amino group, and a quaternary monomer obtained by quaternary preparation of the monomer with a quaternary agent. Examples include ammonium salts.
Examples of cationic monomers include dimethylaminoethyl methacrylate, dimethylaminoethyl methacrylate quaternary salt, dimethylaminoethyl acrylatebenzyl chloride quaternary salt, dimethylaminopropylacrylamide, dimethylaminopropylacrylamide quaternary salt of methyl chloride, and the like.
Monoallylamine, N-methylallylamine, N, N-dimethylallylamine, N-cyclohexylammonium, N, N- (methyl) cyclohexylallylamine, N, N-dicyclohexylammonium, diallylamine, N-methyldiallylamine, N-benzyldiallylamine and theirs. Hydrochloride, sulfate, nitrate, diallylmethylbenzylammonium chloride, diallylmethylbenzylammonium bromide, diallylmethylbenzylammonium iodide, diallylmethylbenzylammonium methylsulfate, diallyldibenzylammonium chloride, diallyldibenzylammonium bromide, iodine Examples thereof include diallyldibenzylammonium compound and diallyldibenzylammonium methylsulfate, and among these, a quaternary ammonium salt such as dimethylaminoethyl methacrylate methyl quaternary salt is preferable.

(1-2-3) Preferred Form The amphoteric ion resin preferably has a nonionic group from the viewpoint of not only optimizing the size of the above-mentioned structure but also improving the wettability.
In order to introduce a nonionic group into the zwitterionic resin, the nonionic monomer (neutral monomer) may be copolymerized together with the anionic monomer and the cationic monomer.
Examples of the nonionic monomer include those containing a hydration functional group such as a hydrophobic alkyl group, a hydroxyl group, an amide group, and an ethylene oxide group.

Examples of the hydrophobic monomer include (meth) acrylate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, and phenyl acrylate. And so on.
Examples of the monomer containing a hydration functional group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, and methallyl alcohol acrylamide. Methacrylicamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide, N-methylolacrylamide, diacetoneacrylamide, acryloylmorpholine, hydroxyethylacrylamide polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate , Methoxypolyethylene glycol acrylate, methoxypolyethylene glycol methacrylate and the like.
Among these, a monomer containing a hydration functional group is preferable, and acrylamide having high hydrophilicity is more preferable, from the viewpoint of promoting adsorption and wetting of condensed water.
That is, the nonionic group of the zwitterionic resin is preferably an amide group.

Examples of the zwitterionic resin include a resin represented by the following formula (I) and a resin having an amide group represented by the formula (II), and the amphoteric ion resin of the formula (I) in terms of antifreeze effect. Is preferable.
The monomers of formula (I) are diallyldimethylammonium chloride (DADMAC) and sodium acrylate from the left.
The monomers of formula (II) are acrylamide, acrylic acid and diallyldimethylammonium chloride (DADMAC) from the left.

(1-2-4) Content ratio of cation and anion The amphoteric ion resin preferably contains a cation and anion at a ratio of 1/9 to 9/1.
If the content ratio of the cation and the anion is less than 1/9, the antifreezing effect of the antifreezing coating film material may be reduced. On the other hand, even if the content ratio of the cation and the anion exceeds 9/1, the freeze-suppressing effect of the freeze-suppressing coating film material can be obtained, but the interaction with the inorganic particles is lowered, so that the water resistance may be lowered. ..
The more preferable content ratio of the cation and the anion is 3/7 to 7/3.
As described in the examples, the +/- ratio in the zwitterionic resin corresponds to the above content ratio.

(1-2-5) Method for Producing Amphoteric Ion Resin The amphoteric ion resin can be produced by a known method, for example, aqueous solution polymerization, emulsion polymerization using water and an organic solvent, suspension polymerization, etc., and the conditions thereof. May be set as appropriate.
For example, in the case of aqueous solution polymerization, a monomer aqueous solution prepared to have a monomer concentration of 10 to 80% by mass is added to the reaction system, the inside of the system is replaced with an inert gas, and then a known polymerization catalyst is added to the number at 20 to 100 ° C. An amphoteric ionic resin is obtained by time polymerization.
Polymerization catalysts include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides such as benzoyl peroxide, 2,2'-azobis- (amidinopropane) hydrochloride and azobiscyanovalerate. Azo-based compounds, and _{redox catalysts in combination with peroxides such as hydrogen peroxide (H 2} O ₂ ) and potassium persulfate and reducing agents such as sodium bicarbonate and ferrous sulfate.

(1-2-6) Mass Average Molecular Weight The zwitterionic resin preferably has a mass average molecular weight of 10,000 or more and 1,500,000 or less.
If the mass average molecular weight of the zwitterionic resin is less than 10,000, the water resistance of the formed coating film may decrease. On the other hand, if the mass average molecular weight of the zwitterionic resin exceeds 1,500,000, the freeze-suppressing coating material may thicken and the coating film may not be formed (film formation).
The mass average molecular weight of the more preferable zwitterionic resin is 10,000 or more and 500,000 or less.

(1-2-7) Blending ratio The blending ratio of the zwitterionic resin in terms of solid content is preferably 0.3% by mass or more and 10.0% by mass or less, and 0.8% by mass or more and 6.0% by mass or less. Is more preferable. By setting the blending ratio of the zwitterionic resin in terms of solid content to 0.3% by mass or more and 10.0% by mass or less, the film forming property of the coating film can be improved.

(1-3) Base Resin The freeze-suppressing coating material preferably further contains a resin other than the zwitterionic resin as the base resin.
By containing the base resin, the film forming property of the freeze-suppressing coating material can be improved.
As the base resin, a hydrophilic nonionic resin, for example, a resin having a non-dissociable hydrophilic group (for example, a hydroxy group) and having neither an anionic group nor a cationic group is preferable.
Examples of the hydrophilic nonionic resin include polyvinyl alcohol, polyvinyl acetal, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyvinyl ether, polyacrylamide, polyvinylpyrrolidone and hydrophilic acrylic resin, and the base resin is selected from polyvinyl alcohol and polyvinylpyrrolidone. It is preferably a nonionic resin to be produced.

The mixing ratio of the base resin in terms of solid content is preferably 3.0% by mass or more and 30.0% by mass or less, and more preferably 5.0% by mass or more and 20.0% by mass or less.
By setting the blending ratio of the base resin in terms of solid content to 3.0% by mass or more, the film forming property of the coating film can be improved. On the other hand, by setting the content of the base resin to 30.0% by mass or less, the freeze suppressing effect of the formed coating film can be further improved.

(1-4) Solvent The antifreezing coating material of the present invention preferably further contains a solvent.
Examples of the solvent include water and alcohol (for example, methanol, ethanol and isopropanol), and among these, water is preferable in terms of stability of inorganic particles and solvent safety.
When a solvent is blended, the solid content concentration of the freeze-suppressing coating material of the present invention is, for example, 1.0% by mass or more and 20.0% by mass or less.

(1-5) Other Components The antifreeze coating material of the present invention may further contain known additives as long as the effects of the present invention are not impaired.
Examples of the additive include organic fillers, surfactants, antibacterial agents, coloring pigments, rust preventive pigments and rust preventive agents.
The mixing ratio of the additive in terms of solid content is, for example, 0.1% by mass or more and 5.0% by mass or less.

(1-6) Method for Producing Antifreeze Coating Material The antifreeze coating material of the present invention contains, for example, inorganic particles and an amphoteric ion resin, and a base resin, solvent and additive used as necessary. It can be obtained by mixing and dispersing, and when a solvent is used, by dissolving or dispersing other constituents in the solvent.

(2) Coating Method The coating method of the present invention is characterized by including a coating step of coating the antifreeze coating material of the present invention on a substrate.

(2-1) Base material The material of the base material is not particularly limited, and examples thereof include metals, ceramics, and resins. As the material of the base material, metal is preferable in terms of durability and ease of processing.
Specific base materials include fins of fin-type heat exchangers, mirrors installed outdoors, aircraft wings and propellers, inner surfaces of freezer rooms and freezers, rain doors and roofs of buildings, and the like.
The coating method is not particularly limited, and examples thereof include a spin coating method, a bar coating method, a spray coating method, a dip coating method, and a roller coating method. Among these, the dip coating method is used in that complicated operations are not required. preferable.

(2-2) Film thickness of coating film The thickness of the coating film formed in the coating step is not particularly limited, but is, for example, 0.2 μm or more and 3.0 μm or less. By setting the thickness of the coating film to 0.2 μm or more, the frost formation suppressing effect can be further improved. By setting the thickness of the coating film to 3.0 μm or less, the function of the base material (for example, when the base material is fins, the heat exchange function) can be maintained.

(2-3) Pretreatment The coating method of the present invention preferably further includes a pretreatment step of subjecting the substrate to a degreasing treatment or a chemical conversion treatment before the coating step.
By including the pretreatment step in the coating method, the adhesion between the base material and the coating film can be improved.
Examples of the degreasing treatment include blasting treatment, steam treatment, solvent cleaning method, alkaline degreasing treatment and acid cleaning treatment.
Further, examples of the chemical conversion treatment include chromate treatment and phosphate treatment. In the coating method of the present invention, it is preferable that the base material is subjected to both degreasing treatment and chemical conversion treatment. In this case, it is preferable to perform a chemical conversion treatment after the degreasing treatment.

The coating method of the present invention preferably further includes a heating step of heating the substrate after the coating step.
The heating step promotes the removal of volatile components in the coating material, and the coating film can be formed more easily and reliably. The heating conditions can be, for example, a heating temperature of 100 ° C. or higher and 200 ° C. or lower, and a heating time of 30 minutes or longer and 2 hours or shorter.

(3) Fin Material The fin material of the present invention is coated with the antifreeze coating material of the present invention.
The fin material of the present invention can be obtained, for example, by forming a coating film on the fin material by the above-mentioned coating method for the freeze-suppressing coating film material of the present invention.
The antifreezing coating material of the present invention is not limited to the above fin materials, but is applied to structures exposed to the natural environment that require suppression of dew condensation and freezing, devices that are repeatedly heated and cooled, and members constituting them. can do.
The target material is not particularly limited as long as it can form a coating film, and examples thereof include (2) a coating method and (2-1) a base material.

Hereinafter, the present invention will be specifically described with reference to Production Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.
First, the materials used in Production Examples, Examples and Comparative Examples will be described.
The type / abbreviation / used example is shown in parentheses of the first item.

(Inorganic particles / ST-AK / Examples 1 to 11 and Comparative Examples 1 to 6)
Silica sol: "Snowtex (registered trademark) ST-AK" manufactured by Nissan Chemical Co., Ltd., sol containing silica particles and water with cationic surface, solid content concentration 23% by mass (silica 19% + aluminum) 4%), average particle size of silica particles 12 nm
(Inorganic particles / F1000 / Examples 1 to 11 and Comparative Examples 1 to 6)
Alumina sol: "Aluminum sol-F1000" manufactured by Kawaken Fine Chemicals Co., Ltd .: Sol containing acicular aluminum oxide particles and water, solid content concentration 5.0% by mass, average major axis of acicular aluminum oxide particles 1,400 nm, acicular Average minor axis of aluminum oxide particles 4 nm

(Zwitterionic resin / 39MF / Examples 1 and 4)
An acrylamide / acrylic acid / diallyldimethylammonium chloride copolymer (“Cosmote V-39MF” manufactured by Senka Co., Ltd., solid content concentration: 10% by mass, resin mass average molecular weight: about 1,400,000) was used as it was.

(Zwitterionic resin / ZCA100L / Example 2)
100 parts by mass of diallylamine hydrochloride / acrylamide / acrylic acid copolymer (“Unisense ZCA100L” manufactured by Senka Co., Ltd., solid content concentration 23% by mass, mass average molecular weight of resin about 100,000) was added to 130 parts by mass of water. , An aqueous solution of an amphoteric resin having a solid content concentration of 10% by mass was obtained.

(Zwitterionic resin / ZCA1000L / Example 3)
100 parts by mass of diallyldimethylammonium chloride / acrylic acid copolymer (“Unisense ZCA1000L” manufactured by Senka Co., Ltd., solid content concentration 40% by mass, mass average molecular weight of resin 300,000) was added to 300 parts by mass of water to solidify. An aqueous solution of an amphoteric resin having a partial concentration of 10% by mass was obtained.

(Zwitterionic resin / L-410W / Comparative Example 4)
100 parts by mass of polymethacryloylethyldimethylbetaine (“Plus size L-410W” manufactured by Reciprocal Chemical Industry Co., Ltd., solid content concentration 31% by mass, mass average molecular weight of resin about 100,000) was added to 210 parts by mass of water. An aqueous solution of an amphoteric resin having a solid content concentration of 10% by mass was obtained. This was used in place of the zwitterionic resin in Comparative Example 4.

(Zwitterionic resin / L-450W / Comparative Example 5)
Methacryloylethyl dimethylbetaine, methacryloyl ethyl trimethylammonium chloride, 2-hydroxyethyl methacrylate copolymer ("Plus size L-450W" manufactured by Mutual Chemical Industry Co., Ltd., solid content concentration 40% by mass, resin mass average molecular weight about 100, 000) 100 parts by mass was added to 300 parts by mass of water to obtain an aqueous resin solution having a solid content of 10% by mass. This was used in place of the zwitterionic resin in Comparative Example 5.

(Zwitterionic resin / PL / Comparative Example 6)
100 parts by mass of a polylysine aqueous solution (“polylysine aqueous solution 25% solution” manufactured by JNC Co., Ltd., solid content concentration 25% by mass, resin mass average molecular weight of about 4,000, natural polymer) was added to 150 parts by mass of water. An aqueous solution of an amphoteric resin having a solid content concentration of 10% by mass was obtained. This was used in place of the zwitterionic resin in Comparative Example 6.

(Nonion resin / PVA-PLL / Comparative example 1)
100 parts by mass of powdered polyvinyl alcohol (“PVA (163-16355)” manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., solid content concentration of 98% by mass or more, average degree of polymerization of resin 3,500, partial saponification 86-90 mol%) , Was added to 900 parts by mass of water to obtain a nonionic resin aqueous solution having a solid content concentration of 10% by mass. This was used in place of the zwitterionic resin in Comparative Example 1.
When adding the powdered polyvinyl alcohol resin to water, the work of adding a small amount of the powdered polyvinyl alcohol resin to the water and then sufficiently stirring the solution until the powdered polyvinyl alcohol resin is completely dissolved is performed. Repeated.

(Nonion resin / AAm / Comparative example 2)
100 parts by mass of acrylamide homopolymer (“EFH-06” manufactured by Senka Co., Ltd., solid content concentration: 15% by mass, resin mass average molecular weight: about 500,000) was added to 50 parts by mass of water, and the solid content concentration was 10% by mass. % Nonion resin aqueous solution was obtained. This was used in place of the zwitterionic resin in Comparative Example 2.

(Anionic resin / DL40 / Comparative example 3)
100 parts by mass of sodium polyacrylate (“DL40” manufactured by Nippon Catalyst Co., Ltd., solid content concentration 40% by mass, mass average molecular weight of resin about 3,500) was added to 300 parts by mass of water, and the solid content concentration was 10% by mass. An aqueous solution of anionic resin was obtained. This was used in place of the zwitterionic resin in Comparative Example 3.

(Base resin (nonion resin) / PVA-FM / Examples 1 to 11 and Comparative Examples 1 to 6
100 parts by mass of powdered polyvinyl alcohol (“PVA (163-11485)” manufactured by Wako Pure Chemical Industries, Ltd., solid content concentration of 98% by mass or more, average degree of polymerization of resin 1,600, complete saponification of 98 mol%) is added to water. It was added to 900 parts by mass to obtain a base resin aqueous solution having a solid content concentration of 10% by mass.
When adding the powdered polyvinyl alcohol resin to water, the work of adding a small amount of the powdered polyvinyl alcohol resin to the water and then sufficiently stirring the solution until the powdered polyvinyl alcohol resin is completely dissolved is performed. Repeated.

The materials used in the preparation of the zwitterionic resins of Production Examples 1 to 7 will be described.
The type / compound name / abbreviation is shown in parentheses of the first item.
(Nonion Monomer / Acrylamide / A Am)
"Product code: A0139" manufactured by Tokyo Chemical Industry Co., Ltd.
(Anion monomer / acrylic acid / AA)
"Product code: A0141" manufactured by Tokyo Chemical Industry Co., Ltd.
(Cation Monomer / Dimethylaminoethyl methacrylate Methyl chloride quaternary salt (also known as trimethyl-2-methacloyloxyethylammonium chloride) / 4N)
"Product code: M0918" manufactured by Tokyo Chemical Industry Co., Ltd., 80% aqueous solution)
(Initiator / Ammonium Persulfate / APS)
"Product code: A2098" manufactured by Tokyo Chemical Industry Co., Ltd.

(Production Example 1: Preparation of amphoteric ion resin (amphoteric 1))
The monomer components, the polymerization initiator, and the deionized water as the reaction solvent shown in Table 1 were put into a separable flask having a capacity of 1000 mL, and kept at a temperature of 70 to 80 ° C. for 4 hours while stirring in a nitrogen atmosphere. The monomer component was polymerized. Then, deionized water was added to the reaction mixture to adjust the solid content concentration to 5% by mass to obtain an aqueous solution of an amphoteric ion resin (amphoteric 1).
The mass average molecular weight (MW) of the obtained polymer was measured by GPC (gel permeation chromatography).

(Production Examples 2-7: Preparation of amphoteric ion resin (amphoteric 2-7))
In Production Examples 2 and 3, as shown in Table 1, amphoteric 2 and 3 were prepared in the same manner as in Production Example 1 (amphoteric 1) except that the amounts of the initiator and deionized water were adjusted to change the molecular weight. Obtained and their mass average molecular weight (MW) was measured.
In Production Examples 4 to 7, as shown in Table 1, amphoteric 4 to 7 were obtained in the same manner as in Production Example 1 (amphoteric 1) except that the monomer ratio was changed, and their mass average molecular weights (MW) were determined. It was measured.

[Example 1: Preparation of antifreezing coating material]
According to the formulations shown below and Table 2, deionized water as an inorganic particle, resin and solvent was put into a beaker having a capacity of 2000 mL, and the mixture was stirred and mixed with a magnetic stirrer to obtain a freeze-suppressing coating material (paint).
Inorganic particles / silica sol (ST-AK)
320 parts by mass (solid content 73.6 parts by mass, compounding ratio 69.0% by mass in terms of solid content)
Inorganic particles / alumina sol (F1000)
200 parts by mass (10 parts by mass of solid content, 9.4% by mass of compounding ratio in terms of solid content)
Base resin / PVA aqueous solution 400 parts by mass (solid content 20 parts by mass, compounding ratio in terms of solid content 18.8% by mass)
Amphoteric ion resin / acrylamide / acrylic acid / diallyldimethylammonium chloride copolymer 60 parts by mass (solid content 3 parts by mass, compounding ratio in terms of solid content 2.8% by mass)
Solvent / water 760 parts by mass

[Examples 2-11: Preparation of antifreezing coating material]
A freeze-suppressing coating material (paint) was obtained in the same manner as in Example 1 except that the formulation was changed to that shown in Table 2.
[Comparative Examples 1 to 6: Preparation of Antifreeze Coating Material]
Frozen in the same manner as in Example 1 except that the zwitterionic resin of the present invention was changed to a nonionic resin, an anion resin or an amphoteric ion resin (betaine resin) outside the provisions of the present invention and changed to the formulation shown in Table 3. An inhibitory coating material (paint) was obtained.

[Evaluation]
The frost formation (freezing) suppressing effect and water resistance of the coating film formed by the antifreezing coating film materials (coating liquids) of Examples 1 to 11 and Comparative Examples 1 to 6 were evaluated by the following methods.

[Frost (freezing) test]
An aluminum plate (40 mm × 40 mm × thickness 1 mm) was prepared as a base material.
A powdery standard degreasing agent (“Surf Cleaner 53NF” manufactured by Nippon Paint Surf Chemicals Co., Ltd.) was dissolved in water to prepare a degreasing treatment liquid (medium alkali) having a concentration of 3% by mass.
The obtained degreasing treatment liquid was heated to a temperature of 60 ° C., the base material was immersed for 2 minutes (defatting treatment), and after the immersion, the base material was washed with pure water.
Since the antifreeze coating material of Example 4 could not be formed due to thickening at a concentration of 8% by mass, the concentration was set to 5% by mass, and the antifreeze coating material of Examples 5 to 11 had the same experimental conditions. Therefore, the concentration was set to 8% by mass.
Since the freeze-suppressing coating material of Example 5 could not be formed at a concentration of 8% and could be formed at a concentration of 5%, it is shown that the film can be formed when the mass average molecular weight MW is low.
Further, Examples 5 to 7 and 8 to 11 show the effect of MW and the effect of the ratio of functional groups based on Example 5 (comparison: REF).

A liquid standardized chemical conversion agent (“Alsurf 312” manufactured by Nippon Paint Surf Chemicals Co., Ltd.) was added to water to prepare a chemical conversion treatment liquid having a concentration of 3% by mass.
The obtained chemical conversion treatment liquid was heated to a temperature of 45 ° C., the base material was immersed for 2 minutes (chemical conversion treatment), and after the immersion, the base material was washed with pure water.

The base material after the pretreatment was immersed in a coating liquid adjusted to a temperature of 23 ° C. for 30 seconds (coating step). After the immersion, the base material was shaken lightly to remove excess coating liquid adhering to the edge of the base material.
The base material after the coating step was placed in an oven set at a temperature of 150 ° C. and heated for 1 hour (heating step). A coating film was formed on the substrate by the above steps, and this was used as a sample plate (test substrate) for evaluation. The thickness of the coating film was 1 μm.

As a device for cooling the sample plate, a cooling plate equipped with an air-cooled Perche unit equipped with a Perche element and an exhaust heat fan was prepared.
The sample plate was placed on the cooling plate under the conditions of low temperature and high humidity (temperature 12 ° C., humidity 85% RH).
The cooling plate was set to a temperature of -1 ° C. and allowed to stand for 1 hour (frost formation test). After that, the surface of the sample plate was observed, and it was visually confirmed whether or not the condensed water was frozen and frost was formed. After that, the temperature of the cooling plate was changed to -2 ° C, -3 ° C and -4 ° C, and the same frost formation test was performed.
As Comparative Example 7 (blank test), a base material (aluminum plate) that does not form a coating film was used as it was as a sample plate, and a frost formation test was performed in the same manner.

In the frost formation test, the effect of suppressing frost formation (freezing) was evaluated by applying the result of the highest temperature (maximum frost formation temperature) among the temperatures at which frost occurred to the following criteria.
A (excellent): No frost was formed at -1 ° C to -4 ° C B (Good): No frost was formed at -1 ° C or -3 ° C, but frost was formed at -4 ° C C (possible) : No frost at -1 ° C or -2 ° C, but frost at -3 ° C D (impossible): No frost at -1 ° C, but frost at -2 ° C Evaluation results Is shown in Table 4. “Y” in Table 4 indicates that frost formation at that temperature could be suppressed, and “N” indicates that freezing of condensed water could not be suppressed.

[Water resistance test]
A sample plate was prepared in the same manner as in the frost formation (freezing) test.
A coating film was formed on an aluminum plate that had been weighed in advance before the coating film was formed, the aluminum plate after the coating film was dried was weighed, and the coating film mass WB (g) was obtained from the weighing difference.
The sample plate was immersed in 100 mL of deionized water at room temperature for 24 hours.
After the treatment, the sample plate is dried under the condition of 105 ° C. × 1 hour (after removing the water content of the sample plate), weighed, the coating film mass WA (g) is obtained from the difference in the weighing results, and further immersed by the following formula. The residual ratio WR of the coating film due to the treatment was determined.
WR (%) = [(WB-WA) / WB] x 100
The water resistance was evaluated by applying the result of the residual ratio of the obtained coating film to the following criteria.
〇; Residual rate of coating film 95% or more Δ; Residual rate of coating film 90% or more and less than 95% ×; Residual rate of coating film less than 90% The cases of "○" and "△" were judged to have good water resistance. ..
The evaluation results are shown in Table 4.

The following can be seen from the results in Tables 2 and 3 and Table 4.
-The antifreeze coating film material of the present invention of Examples 1 to 11 has an excellent antifreeze effect and water resistance.-The conventional antifreeze coating film material of Comparative Examples 1 to 5 has water resistance. Even if it is, the antifreeze effect is inferior. ・ The antifreeze coating film material of the prior art of Comparative Example 6 does not have water resistance and is inferior in antifreeze effect. ・ The antifreeze coating film material of Examples 5 to 7. According to the comparison, when the molecular weight of the copolymerized polymer is low, the interaction between the base material and the inorganic particles is weakened, and the water resistance tends to be low. When the molecular weight is high, the film forming property is lowered due to thickening. -According to the comparison of the antifreeze coating materials of Examples 5 and 8 to 11, whether the molar ratio of the cation and the anion is too high or too low, the + ion and the-ion in the molecule However, the antifreeze effect tends to be low because the meeting is weakened.

The freeze-suppressing coating material and coating method according to the embodiment of the present invention can be used as a coating material and coating method for suppressing freezing (frost) on the surface of a base material such as fins of a fin-type heat exchanger.

1 Zwitterionic resin 2 Inorganic resin particles 3 Base resin 4 Base material

Claims (12)

A freeze-suppressing coating material comprising inorganic particles and a zwitterionic resin composed of a copolymerized polymer of at least one anionic monomer and at least one cationic monomer. The antifreeze coating film material according to claim 1, further containing a resin other than the zwitterionic resin as a base resin. The antifreezing coating material according to claim 2, wherein the base resin is a nonionic resin selected from polyvinyl alcohol and polyvinylpyrrolidone. The antifreeze coating material according to any one of claims 1 to 3, wherein the inorganic particles are silica particles or aluminum oxide particles. Claim 1 The inorganic particles are spherical inorganic particles having an average particle size of 5 nm or more and 100 nm or less, or acicular inorganic particles having an average major axis of 100 nm or more and 4,000 nm or less and an average minor axis of 0.5 nm or more and 20 nm or less. The antifreeze coating material according to any one of 4 to 4. The antifreezing coating material according to any one of claims 1 to 5, wherein the zwitterionic resin has a mass average molecular weight of 10,000 or more and 1,500,000 or less. The antifreeze coating material according to any one of claims 1 to 6, wherein the zwitterionic resin has a nonionic group. The antifreezing coating material according to claim 7, wherein the nonionic group is an amide group. The antifreezing coating material according to any one of claims 1 to 8, wherein the zwitterionic resin contains a cation and an anion at a ratio of 1/9 to 9/1. A coating method comprising a coating step of coating the antifreeze coating material according to any one of claims 1 to 9 on a substrate. The coating method according to claim 10, further comprising a pretreatment step of subjecting the base material to a degreasing treatment or a chemical conversion treatment before the coating step. A fin material coated with the antifreeze coating material according to any one of claims 1 to 9.

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