Humidity control coating material, humidity control sheet, and method for preventing dew condensation

Abstract

To provide: a humidity control coating material that is the coating material having sufficient humidity control properties, whereas a coating film formed from the coating material has flexibility; and a method for preventing dew condensation.SOLUTION: A humidity control coating material includes a synthetic resin and an inorganic porous material, and has a pigment volume concentration in a range of 45-55%. Thereby, a coating film formed from the coating material has flexibility. Dew condensation of an internal wall surface or a ceiling surface can be prevented by disposing a coating film layer formed from the humidity control coating material on the internal wall surface or the ceiling surface.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a moisture-conditioning coating material for use on the interior walls and ceilings of buildings, warehouses, etc., and a method for preventing condensation. [Background technology]

[0002] Traditionally, interior walls and ceilings have been covered with wallpaper or painted with paint to improve their appearance and prevent them from getting dirty, resulting in beautiful, clean surfaces. Furthermore, in order to improve comfort, many proposals have been made to add value to these interior materials.

[0003] One of the added values ​​is interior materials with humidity control properties that can adjust the humidity inside a room. By installing this interior material on the walls and ceiling of a room, these surfaces can be given humidity control properties, which helps to regulate the humidity inside the room and prevent condensation, creating a comfortable indoor space. For example, Patent Document 1 describes a coating composition that prevents condensation by rapidly absorbing a large amount of moisture or condensed water when the coating surface falls below the dew point temperature, and rapidly releasing the absorbed water when the coating surface rises above the dew point temperature.

[0004] Furthermore, Patent Document 2 describes a moisture-conditioning wall material that is lightweight and easy to install, and that is able to fully exhibit moisture absorption capacity while satisfying long-term moisture-conditioning performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 57-151661 [Patent Document 2] Japanese Patent Application Publication No. 2019-196625 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the coating composition of Patent Document 1 contains a large amount of diatomaceous earth to improve humidity control performance, which means that the coating is not very flexible and cracks may occur in the coating film if the painted substrate moves.Furthermore, the humidity-control wall material of Patent Document 2 is not flexible, making it difficult to apply along the substrate. The present invention provides a humidity-conditioning coating material that has sufficient humidity-conditioning performance and yet provides a coating film formed from the coating material that is flexible, and a method for preventing condensation. [Means for solving the problem]

[0007] The moisture-regulating coating material contains synthetic resin and inorganic porous material and has a pigment volume concentration (hereinafter also referred to as PVC) in the range of 45 to 55%, which makes the coating film formed from the coating material flexible. By including an anti-drying agent in the humidity-conditioning coating material, the coating film formed from the coating material will have better humidity-conditioning performance.

[0008] The moisture-conditioning coating material is formed in a sheet form, so that it can be easily applied to wall and ceiling surfaces. By providing a coating film layer formed from the humidity-conditioning coating material on an inner wall surface or a ceiling surface, condensation on the inner wall surface or the ceiling surface can be prevented. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below: The present invention is a humidity-conditioning coating material that contains a synthetic resin and an inorganic porous substance and has a pigment volume concentration (PVC) in the range of 45 to 55%. First, the synthetic resin contained in the humidity-regulating coating material of the present invention binds together the various materials that make up the coating material, such as inorganic porous substances, to form a coating film.It is a binder that bonds the base and the coating film together, affects the hardness of the coating film, and is one of the elements that allows the coating film to respond to movements such as the absorption and release of moisture.

[0010] Examples of synthetic resins that can be used include acrylic resin, silicone resin, acrylic silicone resin, fluororesin, polyurethane resin, styrene resin, epoxy resin, melamine resin, alkyd resin, vinyl chloride resin, vinyl acetate resin, and polyester resin. The synthetic resin may be used alone or in a mixture of two or more kinds, and the monomers constituting the synthetic resin may be ordinary ones, either alone or copolymerized.

[0011] These synthetic resins are often dispersed in water to form synthetic resin emulsions, which are aqueous coating materials using water as a solvent, and are preferred for their ease of handling and workability. Among synthetic resin emulsions, acrylic synthetic resin emulsions, acrylic styrene synthetic resin emulsions, acrylic silicone synthetic resin emulsions, and urethane synthetic resin emulsions, which have good water resistance, are preferably used, and those that have excellent miscibility with the inorganic porous materials described below are preferred.

[0012] The glass transition point (hereinafter also referred to as Tg) of this synthetic resin is preferably in the range of −20 to 40° C. If the Tg of the synthetic resin is lower than −20° C., the formed coating film is prone to attracting contaminants such as fingerprints. In addition, when the coating absorbs moisture, pollutants such as dust in the air tend to come close to the coating, and these pollutants also tend to accumulate near the surface of the coating, making them more likely to adhere.

[0013] If the Tg of the synthetic resin is higher than 40°C, the formed coating film will become hard and may not be able to respond well to the movement of the coating film due to the absorption and release of moisture or the movement of the base material, which may cause the coating film to crack. More preferably, the Tg of the synthetic resin is in the range of -15 to 30°C, and this range results in a well-balanced coating film that is resistant to staining and is soft and less prone to cracking, adapting to the movement of the substrate, etc.

[0014] The inorganic porous substance contained in the humidity-conditioning coating material of the present invention has a significant effect on the humidity-conditioning performance of the humidity-conditioning coating film due to its water absorption / release performance and water storage performance. These inorganic porous substances include diatomaceous earth, zeolite, silica gel, alumina, lime, allophane, kaolin, halloysite, pumice, clay, shirasu, celite, talc, gypsum, vermiculite, and bentonite.

[0015] Other examples include pozzolan, cement, sepiolite, alumina silicate, silica aluminate, calcium silicate, magnesia silicate, silica magnesianate, and activated carbon. These inorganic porous substances are selected appropriately based on their moisture-regulating performance, coating suitability such as stability and workability, and coating film properties such as water resistance. There are no particular restrictions on the type, but diatomaceous earth is preferably used due to its moisture absorption and release properties.

[0016] Diatomaceous earth is made from fossilized unicellular algae called diatoms, and can be prepared by drying and crushing these deposits into fine particles. Its main component is silicon dioxide, making it chemically stable, and its surface is covered with countless minute pores measuring 0.1 to 0.2 μm, arranged in a regular pattern in the shape of circles or needles. Due to its ultra-porous structure with countless tiny holes, it is relatively lightweight, has an extremely large specific surface area, and has excellent water absorption properties.As a result, it has the ability to absorb moisture through its porous structure when the humidity in a room is high, and release moisture when the humidity is low, providing humidity control.

[0017] In addition to this humidity-regulating property, the coating film also has deodorizing properties and heat insulation properties due to the air trapped in the countless minute pores. The inorganic porous material has an average particle size in the range of 1.0 to 30.0 μm. If the inorganic porous material has an average particle size smaller than 1.0 μm, its surface area increases, its miscibility with the humidity-conditioning coating material decreases, the viscosity of the resulting coating material increases, workability decreases, and the resulting coating film becomes brittle and hard.

[0018] If the average particle size of the inorganic porous material is larger than 30.0 μm, the surface area will be small, resulting in poor moisture-regulating properties such as water absorption. In addition, the particles of the inorganic porous material will be exposed in the coating film formed, making it difficult to achieve the desired finish and making it easier for airborne dust to accumulate. Preferably, the average particle size is in the range of 3.0 to 25.0 μm, which provides good workability for the humidity-conditioning coating material, a good coating film finish, and stain resistance. The average particle size is the median size calculated from the volume-based particle size distribution measured by laser diffraction.

[0019] The content of the inorganic porous substance is preferably in the range of 5.0 to 50.0% by weight of the coating material, which allows for a sufficient humidity-regulating effect. If the content of inorganic porous material is less than 5.0% by weight, the coating film will absorb less water and the humidity control properties will be poor. If the content is more than 50.0% by weight, the absorption capacity will cause the coating material to absorb the blended water, making the humidity control coating material less workable and difficult to apply.

[0020] Furthermore, the moisture-conditioning coating film that is formed absorbs a large amount of water, which increases the amount of water absorbed by the coating film, increasing the weight and load on the coating film, which can cause the coating film to peel off or crack. Preferably, the content is in the range of 10.0 to 25.0% by weight. Within this range, it is easy to obtain a coating material that is easy to work with and has excellent moisture-regulating properties, and can adequately respond to the movement of the coating film due to the absorption and release of moisture.

[0021] The pigment volume concentration of the humidity-conditioning coating material of the present invention is in the range of 45 to 55%. If the pigment volume concentration of the humidity-conditioning coating material is less than 45%, the content of inorganic porous material will be low, resulting in poor humidity-conditioning performance of the coating film formed from the humidity-conditioning coating material. If the pigment volume concentration is more than 55%, the coating film formed from the humidity-conditioning coating material will become hard and may crack due to movement of the base. More preferably, the pigment volume concentration is in the range of 48 to 53%, and by being in this range, the coating film formed from this humidity-conditioning coating material will have humidity-conditioning properties and flexibility.

[0022] The humidity-conditioning coating material of the present invention preferably contains an anti-drying agent. By adding an anti-drying agent to the humidity-conditioning coating material, the humidity-conditioning performance of the coating film formed from the humidity-conditioning coating material is improved. The reason for this is not clear, but it is thought that anti-drying agents have the effect of attracting moisture, and that by including an anti-drying agent in a humidity-regulating coating material, moisture in the air is more easily absorbed by the coating film formed by the humidity-regulating coating material, thereby improving humidity-regulating performance.

[0023] Examples of such drying inhibitors include polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, and glycerin, or their alkyl ethers; pyrrolidones such as polyvinylpyrrolidone and N-methyl-2-pyrrolidone; amides, dimethyl sulfoxide, imidazolidinone, thiourea, modified urea, and phenolic compounds. These drying inhibitors are appropriately selected depending on the coating material suitability such as stability and workability, and the coating film properties such as water resistance, and there are no particular restrictions on the type, but modified urea is preferably used.

[0024] The content of this anti-drying agent in the coating material is preferably in the range of 5 to 10% by weight. By having the content of the anti-drying agent in this range, the humidity-conditioning performance of the coating film formed from the humidity-conditioning coating material is improved. If the content is less than 5% by weight, little improvement in humidity control performance is seen, and if the content is more than 10% by weight, too much moisture is absorbed, exceeding the water absorption capacity of the humidity control coating film, and water may float on the coating film.

[0025] The humidity-conditioning coating material of the present invention can further contain pigment components and additives, such as inorganic pigments such as titanium oxide, zinc oxide, and iron oxide, and organic pigments, as well as extender pigments such as calcium carbonate, calcium silicate, kaolin, talc, clay, aluminum hydroxide, bentonite, white carbon, and precipitated barium. These pigment components can be used alone or in combination of two or more types, and this is preferably done. By mixing the pigment components into the coating material, the humidity-conditioning performance can be adjusted.

[0026] As additives, various additives commonly used in coating materials, such as surfactants used as defoamers, dispersants, wetting agents, etc., high-boiling point solvents used as film-forming aids, antifreeze agents, thickeners and leveling agents for viscosity adjustment, preservatives, anti-algae agents, anti-mold agents, antibacterial agents, pH adjusters, crosslinking agents, silane coupling agents, etc., can be added as needed. The humidity-conditioning coating material of the present invention can be obtained by mixing and dispersing the components. The method of mixing and dispersing is not particularly limited, and can be carried out using a mixer such as a general mixer.

[0027] The viscosity of the humidity-conditioning coating material obtained as described above is preferably in the range of 20,000 to 27,000 mPa·s. A viscosity in this range makes it easy to apply the coating material and form it into sheets, as described below. The viscosity was measured using a BH type viscometer at 23°C and 20 rpm.

[0028] The humidity-conditioning coating material of the present invention can be applied to form a coating film by a commonly used coating method such as spray coating, roller coating, brush coating, or trowel coating. The coating film may also be processed into a sheet form, which allows for easy application without the need for advanced coating techniques such as spray coating or roller coating, and the coating film has a uniform thickness, resulting in stable humidity control performance.

[0029] A method for producing a humidity-conditioning sheet formed from the humidity-conditioning coating material is to laminate the humidity-conditioning coating material on release paper or a peelable resin sheet, etc., dry and harden the humidity-conditioning coating material on the release paper, etc., and then peel off the release paper, etc., to produce a sheet of coating film formed from the humidity-conditioning coating material. It is also possible to form a sheet by layering a humidity-regulating coating material on a substrate layer, drying and curing it on the substrate layer, and forming a coating layer on the substrate layer. The presence of the substrate layer increases the strength of the sheet and improves workability, so a sheet with a coating layer formed on a substrate layer is more preferred.

[0030] Methods for laminating the humidity-conditioning coating material on the release paper or base layer include the above-mentioned coating method and a method for applying the humidity-conditioning coating material on the release paper or base layer using a knife coater or the like. Furthermore, it is also possible to pour the humidity-conditioning coating material into a mold and, if necessary, attach a release paper or a base layer to the surface of the humidity-conditioning coating material on the side opposite the mold.

[0031] The substrate layer can be made of woven or nonwoven fabric. There are no particular restrictions on the material of the substrate layer, but considering non-combustibility, inorganic fibers with high heat resistance are preferred. Furthermore, glass fibers are preferred from the viewpoints of flexibility and availability, and glass fiber content of 30% by weight or more is more preferred. By containing 30% or more by weight of glass fiber, the humidity-conditioning coating material can penetrate more easily and the adhesion between the humidity-conditioning coating material and the base layer can be improved.

[0032] The weight of the base material layer is 30 to 100 g / m 2 When the basis weight is in this range, the humidity-conditioning sheet can be easily produced and applied. Furthermore, this substrate layer may be sealed with a resin, paint, sealant, etc., in order to prevent leakage of the raw materials of the humidity-conditioning coating material when the humidity-conditioning coating material is laminated.

[0033] The thickness of the coating layer of the humidity-conditioning sheet is preferably 0.45 to 0.55 mm. When the thickness of the coating layer is in this range, the humidity-conditioning performance of the humidity-conditioning sheet is sufficient. If the thickness of the coating layer is thinner than 0.45 mm, the humidity-conditioning performance deteriorates, and if it is thicker than 0.55 mm, the coating layer is prone to cracking. The thickness of the substrate layer is preferably 0.2 to 0.4 mm. If the thickness of the substrate layer is thinner than 0.2 mm, the coating material may seep through to the back surface when applied, and sufficient strength cannot be obtained, which is not preferable. If the thickness of the substrate layer is thicker than 0.4 mm, flexibility is lost, which is not preferable.

[0034] The humidity-conditioning sheet of the present invention is preferably flexible; if it is not flexible, the humidity-conditioning sheet will be difficult to apply and may crack when applied to a curved surface. This flexibility is such that there are no cracks in the coating film when checked in accordance with the flexibility test of JIS A6909.

[0035] The humidity-conditioning sheet of the present invention can be provided with an adhesive on the back surface of the sheet, and although there are no particular limitations, various adhesives such as synthetic rubber, vinyl acetate, polymer cement, acrylic rubber, and modified silicone can be used for this adhesive treatment. These include solvent-based types that use an organic solvent as a solvent, aqueous-based types that use a synthetic resin emulsion that uses water, and solventless types that do not use any of these, but the aqueous and solventless types are preferably used.

[0036] More preferably, it is one whose main component is a synthetic resin emulsion, which is easy to handle, can provide sufficient adhesive strength, and also provides a sufficient adhesive strength for the adhesive layer. Furthermore, for adhesives that use synthetic resin emulsion as the main ingredient, the tackiness after the adhesive has dried and hardened can be easily adjusted by adjusting the softness of the resin in the synthetic resin emulsion or by adding a high-boiling point solvent such as a plasticizer, and the durability of the tackiness can also be adjusted by adjusting the boiling point of the high-boiling point solvent.

[0037] Alternatively, double-sided tape may be used for this adhesive processing. This double-sided tape is made up of the above-mentioned adhesive and nonwoven fabric, and the adhesive layer is protected by release paper. With this double-sided tape, one adhesive layer is attached to a sheet, and the other adhesive layer, protected by a release paper, is attached to a substrate after the release paper is peeled off.

[0038] This release paper is used to protect the adhesive layer until the sheet is attached to the substrate, and is not particularly limited, and a commercially available release paper can be used. These include paper or film processed with release agents such as silicone, wax, and fluororesin, as well as synthetic resin films such as polypropylene and polyethylene.

[0039] The condensation prevention method of the present invention involves providing a coating film layer formed from the humidity-conditioning coating material on an interior wall or ceiling surface, preferably an interior wall or ceiling surface in a building, a warehouse, a shipping container, or other location prone to condensation. Materials that make up interior wall or ceiling surfaces include wallboard materials such as ceramic siding boards, flexible boards, calcium silicate boards, gypsum boards, extruded boards, wood wool cement boards, precast concrete boards, and lightweight aerated concrete boards. Other examples include those made of metal materials such as aluminum, iron, and stainless steel, wood materials such as plywood and chipboard, and insulating foam materials made from foamed synthetic resins.

[0040] By applying the humidity-conditioning coating material or attaching a humidity-conditioning sheet to the interior wall surface or ceiling surface constructed from these materials, a coating film layer formed from the humidity-conditioning coating material can be provided. When applying a humidity-conditioning coating material to interior walls or ceilings, a primer such as a sealer may be applied before the humidity-conditioning coating material is applied to improve adhesion and prevent uneven absorption. There are no particular restrictions on the primer paint, and commercially available ones are generally used.

[0041] The moisture-conditioning coating material can be applied by a commonly used coating method such as spray coating, roller coating, brush coating, or trowel coating. The humidity-conditioning sheet can be attached by applying an adhesive to the area to be attached and then attaching the humidity-conditioning sheet on top of that, or by applying double-sided tape to the area to be attached and then attaching the humidity-conditioning sheet on top of that.

[0042] Another method is to prepare a humidity-conditioning sheet with an adhesive-treated backside and apply it to the application area, which is preferable because it provides good workability and a good finish. In this way, a coating layer formed from a humidity-conditioning coating material can be provided on the interior wall surface or ceiling surface, thereby making it less likely for condensation to occur.

[0043] More specific embodiments will be described below. The raw materials shown in Table 1 were mixed uniformly using a dissolver, and the viscosity measured with a BH-type viscometer was adjusted to approximately 24,000 mPa·s to produce a humidity-regulating coating material.

[0044] The synthetic resin emulsion used was an acrylic synthetic resin emulsion with a non-volatile content of 45% and a Tg of -10°C. The inorganic porous material used was diatomaceous earth with an average particle size of 7 μm, which is the median diameter calculated from the volume-based particle size distribution measured by laser diffraction. The drying prevention agent used was modified urea. The extender pigment used was calcium silicate. The coloring pigment used was titanium oxide. The additives used were a defoamer, dispersant, thickener, and film-forming aid.

[0045] [Table 1]

[0046] These humidity-conditioning coating materials were used to prepare coating films or sheets for use as test specimens. The coating films were prepared by spraying the humidity-conditioning coating material onto each test substrate using a lysine gun to a film thickness of 0.5 mm. The sheets were made by using a glass sheet containing 30% by weight of glass fiber as the base layer, applying a humidity-regulating coating material to the glass sheet using a knife coater, and drying at 150°C. When a glass sheet with a thickness of 0.1 mm was used, the coating material soaked into the back of the glass sheet, making it impossible to produce a clean sheet.

[0047] A sheet made using a glass sheet with a thickness of 0.5 mm and a humidity-regulating coating material with a thickness of 0.6 mm developed cracks in the coating material layer, resulting in a sheet with no flexibility. From the above, test specimens were prepared by preparing a glass sheet having a thickness of 0.3 mm and a humidity-conditioning coating layer having a thickness of 0.5 mm, and attaching the sheet to each test substrate using an adhesive.

[0048] The flexibility and humidity control properties of the specimens prepared in this manner were checked. Flexibility was checked in accordance with the flexibility test of JIS A6909. Humidity control properties were checked in accordance with the moisture absorption and desorption test of JIS A6909. Table 2 shows the specifications and test results of each specimen.

[0049] [Table 2]

[0050] The flexibility was evaluated according to the following criteria. ○: No cracks on the surface of the test specimen ×: Cracks are present on the surface of the test specimen The humidity control ability was evaluated according to the following evaluation criteria. ◎: Absorption and release mass is 80g / m 2 End ○: Absorption and release mass is 50g / m 2 More than 80g / m 2 less than ×: Absorption and release mass is 50g / m 2 Less than or not measurable

[0051] Specimen 3 had a high PVC content in the coating material, which caused the coating to harden and crack during the flexibility test. Specimen 4 had a high PVC content in the coating material, which caused the coating to harden and crack during the flexibility test. Also, moisture absorption and desorption was worse than specimen 3, possibly because it was made into a sheet. For specimen 10, the amount of moisture absorption and desorption could not be measured because water floated on the surface of the specimen, possibly due to the large amount of drying prevention agent added to the coating material.

[0052] Next, a humidity-conditioning sheet with the same specifications as Test Specimen 7, with an adhesive backing, was attached to the inner wall of the shipping container. Because this sheet is flexible, it was able to be attached neatly to the shape of the substrate. When the interior walls of a shipping container without a humidity-regulating sheet and a shipping container with a humidity-regulating sheet were inspected in winter, condensation was found on the interior walls of the shipping container without the sheet, but no condensation was found on the interior walls of the shipping container with the sheet attached.

Claims

1. A moisture-regulating coating material containing synthetic resin and inorganic porous material, with a pigment volume concentration (PVC) in the range of 45 to 55%.

2. The humidity-conditioning coating material according to claim 1, which contains an anti-drying agent.

3. A humidity-conditioning sheet in which the humidity-conditioning coating material according to claim 1 or 2 is formed into a sheet shape.

4. a substrate layer containing glass fibers; A coating layer formed from the humidity-conditioning coating material according to claim 1 or 2. A humidity-conditioning sheet comprising at least two layers of the above.

5. A method for preventing condensation, comprising providing an inner wall or ceiling surface with a coating film layer formed from the humidity-conditioning coating material according to claim 1 or 2.

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