JPH01223154A - Composition excellent far infrared ray radiation characteristics and coating therefrom - Google Patents

Abstract

PURPOSE:To obtain the title composition outstanding in hydrophilicity, suitable for e.g., coatings for the inner wall of e.g., hot drying ovens, by blending a water-soluble melamine resin, a curing catalyst, polyvinyl alcohol, a metal compound and ceramic powder. CONSTITUTION:The objective composition comprising (A) a water-soluble melamine resin, (B) a curing catalyst for said melamine resin, (C) polyvinyl alcohol, (D) a metal compound capable of forming a chelate compound with the component C coordinated, and (E) ceramic powder with a granular size of 1-0.05mu in such amounts as follows: 1. 2.5-300pts.wt. of the component A based on 100pts.wt. of the component E, 2. 1.5-350pts.wt. of the component C based on 100pts.wt. of the component E, 3. 0.1-5pts.wt. of the component B based on 100pts.wt. of the component A, 4. 2-10pts.wt. of the component D based on 100pts.wt. of the component C.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an aqueous composition suitably used to obtain a material with excellent far-infrared radiation properties, and in particular to a coating material suitable for obtaining a solid composition such as a coating film with excellent far-infrared radiation properties. be.

[Conventional technology]

It is known that radiating far infrared rays to a heated object accelerates the heating of the heated object. Recently, various technologies utilizing this have been developed, and a large number of heating drying devices equipped with materials having excellent far-infrared radiation characteristics (hereinafter referred to as "far-infrared radiators") have appeared. By the way, ceramics are generally used as far-infrared radiators. Far-infrared radiators made of ceramics have the advantage of semi-permanently unchanging radiation characteristics and strong chemical resistance, but have the disadvantage that they are difficult to coat on the inner walls of, for example, heating drying equipment. Therefore, in order to make it easier to apply to the inner walls of heat-drying equipment, a coating composition in which a far-infrared radiator is powdered and dispersed in a binder solution has been proposed (Japanese Patent Application Laid-Open No. 1983-1989-1).
61782 and JP-A No. 62-256875), the inventions related to these coating compositions are aimed at improving the crack resistance and peeling resistance of the obtained coating film.

[Problem to be solved by the invention]

However, the coating film obtained by coating on the inner walls of heating drying equipment, etc., is required to have excellent hydrophilicity as well as crack resistance and peeling resistance. This is to prevent water droplets from forming on the inner wall surface of the heating drying equipment or the like. The reason why it is necessary to prevent water droplets from forming on the inner wall surface is as follows. That is, when water droplets form on the inner wall surface of a heating drying device, etc., the far infrared rays emitted from the inner wall are absorbed by the water droplets, reducing the far infrared energy reaching the heated object and reducing thermal efficiency. The larger the water droplet, the thicker the optical thickness, and the greater the degree of reduction in thermal efficiency. Therefore, the present invention aims to make the coating film obtained by applying it to the inner wall of heating drying equipment, etc. not only crack-resistant and peel-resistant but also hydrophilic so that water droplets are less likely to form on the inner wall surface. It was done for a purpose. Furthermore, the present invention has been made not only for the purpose of obtaining a coating film, but also for the purpose of obtaining a far-infrared radiator that can be molded into other desired shapes and has an excellent surface hydrophilicity.

[Means to solve the problem]

That is, the present invention provides a water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, polyvinyl alcohol, a metal compound that is coordinated with the polyvinyl alcohol to form a chelate compound, and a ceramic having excellent far-infrared radiation characteristics. This invention relates to an aqueous solution composition characterized by consisting of a powder, and by using this aqueous solution composition as a coating material, a coating film with excellent hydrophilicity and far-infrared radiation properties can be obtained. . Furthermore, by molding this aqueous solution composition into a desired shape, a far-infrared radiator having a desired form that is excellent in hydrophilicity and in far-infrared radiation characteristics can be obtained. The composition of the solid composition obtained by curing this aqueous solution composition is composed of a hardened melamine resin, chelated polyvinyl alcohol, and a ceramic powder with excellent far-infrared radiation properties, and contains melamine resin as an impurity. Contains a curing catalyst to accelerate curing. As the water-soluble melamine resin used in the present invention, any of commercially available monomer resins and multimer resins such as dimer type resins with a certain degree of polycondensation degree may be used. and,
Examples of curing catalysts for water-soluble melamine resins include ammonium salt catalysts such as ammonium chloride, diammonium phosphate, and ammonium sulfamate, hydrochloric acid or sulfamate salts of organic amino alcohols, dimethylaniline hydrochloride, pyridine-hydrochloric acid, and picoline-based catalysts. Organic amine salt catalysts such as monochloroacetic acid, and inorganic metal catalysts such as magnesium chloride, zinc chloride, and zinc sulfate can be used. Among them, it is preferable to use an organic amine salt catalyst, and the water-soluble melamine resin becomes a three-dimensional network polymer due to the curing catalyst, and binds ceramic powder having excellent far-infrared radiation characteristics. As the polyvinyl alcohol used in the present invention, any commercially available completely saponified type, intermediately saponified type, or 9-partly saponified type can be used. The polyvinyl alcohol, preferably in saponified form, is insolubilized by a metal compound which is coordinated to the polyvinyl alcohol to form a chelate compound. Zirconium nitrate is generally used as this metal compound, but other zirconium salts can also be used. Polyvinyl alcohol mainly improves the hydrophilicity of the surface of the solid composition. The ceramic powder with excellent far-infrared radiation properties used in the present invention is made of alumina, silica, and zircon as main components, mixed with oxides such as titanium, cobalt, chromium, nickel, manganese, iron, and magnesium, and fired. Ceramic powder obtained by The size of the powder should be such that it can be easily dispersed uniformly in an aqueous solution, and specifically, a particle size of about 1 μm to 0.05 # is preferable. The blending ratio of the aqueous solution composition according to the present invention is preferably as follows. The amount of the water-soluble melamine resin is about 2.5 to 300 parts by weight per 100 parts by weight of the ceramic powder. Further, the amount of the curing catalyst for the water-soluble melamine resin may be sufficient as long as it is sufficient to cure the water-soluble melamine resin, for example, about 0.1 to 5 parts by weight per 100 parts by weight of the water-soluble melamine resin. good. The amount of polyvinyl alcohol is preferably about 1.5 to 350 parts by weight per 100 parts by weight of the ceramic powder. Further, the metal compound that is coordinated with polyvinyl alcohol to form a chelate compound is about 2 to 10 parts by weight per 100 parts by weight of polyvinyl alcohol.
Preferably it is about 4 to 7 parts by weight. In addition, the total weight of the water-soluble melamine resin, its curing catalyst, polyvinyl alcohol, and the metal compound that coordinates therewith to form a chelate compound is 5 to 300 parts by weight based on 100 parts by weight of the ceramic powder. The weight of the parts is quite large. Then, 100 parts by weight of these solids can be dissolved and dispersed in 100 to 2000 parts by weight of water to obtain an aqueous solution composition according to the present invention. As a method for preparing the aqueous composition according to the present invention, for example, a solution A is prepared by dissolving polyvinyl alcohol and a metal compound such as zirconium nitrate that is coordinated with the polyvinyl alcohol to form a chelate compound in water. A
Separately from the liquid, a water-soluble melamine resin and its curing catalyst are dissolved in water to obtain liquid B. Next, it can be adjusted by mixing liquid A and liquid B and adding ceramic powder therein. The aqueous composition according to the present invention is particularly suitable for use as a paint. Therefore, after being applied to the inner wall of a heat drying device, etc., a hydrophilic coating film can be obtained by applying a heat treatment or the like to harden it. In a solid composition such as a coating film obtained by curing the aqueous composition according to the present invention, the water-soluble melamine resin is cured to become a solid melamine resin. Moreover, polyvinyl alcohol also hardens together with the metal compound to become solid. Ceramic powders do not undergo any changes and are uniformly dispersed in the solid body. The curing catalyst for the water-soluble melamine resin serves a catalytic function to promote the curing reaction of the water-soluble melamine resin, and remains as it is in the solid material. However, since the amount of this compound is small, it does not interfere with the far-infrared radiation characteristics of the ceramic powder.

[Effect]

In the present invention, solid polyvinyl alcohol coordinated with a metal compound that chelates polyvinyl alcohol has excellent hydrophilicity, and the hydrophilicity of the surface of the obtained solid product is improved. Further, in the present invention, the thermosetting water-soluble melamine resin improves the crack resistance and peeling resistance of the obtained solid material. In the present invention, the ceramic powder has excellent far-infrared radiation characteristics and selectively emits far-infrared rays when energized, heated, infrared irradiated, etc., and has the effect of heating and drying objects to be heated.

【Example】

An aqueous solution composition was obtained by dissolving and dispersing the compounds shown in Table 1 below in water. However, A to E in Table 1 are as follows, and only No. 4 is a comparative example. Further, the concentration of the aqueous solution composition was 30%. A: Ceramic powder with excellent far-infrared radiation properties (obtained by mixing and firing 65 parts by weight of zircon, 15 parts by weight of titanium oxide, 13 parts by weight of manganese dioxide, 5 parts by weight of ferric oxide, and 2 parts by weight of chromium oxide). B: Water-soluble melamine resin (manufactured by Nippon Carbide Industries ■, trade name Nikaresin) C1: Curing catalyst (guanidine sulfamate) C2: Curing catalyst (ammonium chloride) C3: Curing catalyst (methylaniline) D: Polyvinyl alcohol E: Aqueous solution composition of zirconium nitrate Nos. 1 to 4 was heated to a thickness of 0.0 mm after degreasing.
It was applied to a 13 m JIS A-1100 thin aluminum plate and dried for 30 seconds in a hot air dryer at 250°C to obtain a coating film. The hydrophilicity, peeling resistance, and cracking resistance of the coating film thus obtained were evaluated. The results are shown in Table 2. Table 1 (unit: parts by weight) Table 2 1): Hydrophilicity was evaluated by contact angle. Contact angle was measured with a gonimeter. When the contact angle is about 40 or less,
Water droplets are less likely to form. 2): Peeling resistance was evaluated by a trichlene immersion test. In the trichlene immersion test, a thin aluminum plate with a coating film adhered to it is immersed in a trichlene solution at 50°C, and the time taken until the film peels off is measured. If the coating film did not peel off even after being immersed for 120 hours, it was judged as "good". 3) Using press molding a for Nidraw press (manufactured by Hidaka Seiki ■), a thin aluminum plate to which the coating film was adhered was continuously formed and subjected to impact, and it was visually determined whether or not cracks occurred in the coating. . "Good" if no cracks are observed
It was determined that

【Effect of the invention】

As explained above, the solid composition such as a coating film obtained by subjecting the aqueous solution composition according to the present invention to heat treatment etc. has a solid film etc. made of chelated polyvinyl alcohol on its surface. Since this coating has excellent hydrophilicity, water droplets are difficult to adhere to.Therefore, the far infrared rays emitted from the solid composition are less likely to be absorbed by the water droplets, and the far infrared rays are not absorbed by the heated object. is reached efficiently. Therefore, heating and drying of the object to be heated is performed efficiently, and a decrease in thermal efficiency can be prevented. Furthermore, since the solid composition such as the coating film according to the present invention has excellent hydrophilicity, lipophilic foreign matter is difficult to adhere to, and therefore, far infrared rays emitted from the solid composition are absorbed by the lipophilic foreign matter. Far-infrared rays efficiently reach the object to be heated, etc., and similarly to the above, there is an effect that a decrease in thermal efficiency can be prevented. Even if lipophilic foreign matter adheres, the adhesion to the hydrophilic coating is small, so it can be easily wiped off with a cloth, and the far-infrared radiation performance can be easily restored. . In addition, since the solid composition of the present invention contains a solid hardened melamine resin, it has excellent adhesion to a carrier such as an aluminum thin plate and is resistant to cracking even when subjected to impact. The coating film obtained by applying it to the inner wall surface of equipment, etc. is resistant to peeling (and cracking), so there is less breakage and damage, and it has the effect that heating drying equipment, etc. can be used successfully for a long period of time. Also plays.

Claims (3)

[Claims] (1) A water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, polyvinyl alcohol, a metal compound that is coordinated with the polyvinyl alcohol to produce a chelate compound, and a ceramic powder with excellent far-infrared radiation characteristics. An aqueous solution composition comprising: (2) A paint comprising the aqueous composition according to claim (1). (3) A solid composition comprising a hardened melamine resin, chelated polyvinyl alcohol, and a ceramic powder with excellent far-infrared radiation characteristics.