JPS60129552A - Heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the corrosion of a heat exchanger and improve the durability and reliability of the equipment by a method wherein two layers of coating, prominent in anti-corrosion property and heat conductivity, are formed on the surface of a heat transfer member made of copper. CONSTITUTION:A coating layer 2 is formed on the surface of the heat transfer member 1 of copper at the side thereof contacting with water by a method wherein a coating, consisting of the binders of acrylic resin, melamine resin and epoxy resin added with the powder of silicon carbide and the powder of a metal having a standard electrode potential of 0 volt or lower, is cured by heating. In the layer 2, the powder 2a of silicon carbide and the powder of metal 2b are dispersed uniformly. The binder made by mixing acrylic resin, melamine resin and epoxy resin is coated on the layer 2 and is cured by heating whereby the coating layer 3 is formed. In this constitution, acrylic resin and melamine resin, employed in the layers 2, 3 as the binder, make a three-dimensional tight reticulated structure in the molecular structures thereof upon curing by heat, therefore, the permeability of the molecule of water or corrosive elements is small while pin holes are very few due to the low transition point of glass, whereby the invasion of the corrosive elements into the member 1 may be precluded mostly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat exchanger used in water heaters, water heaters, etc., and having a copper heat transfer member.

Conventional Structures and Their Problems Conventionally, the heat transfer members of this type of heat exchanger have often been made of copper, which has good workability and thermal conductivity and is corrosion resistant to ordinary tap water. However, in water environments such as groundwater where the pH (hydrogen ion concentration) is 7 or less and there are large amounts of free carbon dioxide (carbon dioxide gas dissolved in water), chlorine ions, nitrate ions, and other anions, the copper is corroded. Ru.

Copper ions eluted by drinking water react with fatty acids such as soap to form blue copper complex salts, which discolor water to blue, and the copper complex salts adsorb to towels used in baths, etc. There were problems such as the color turning blue.

As a means of preventing corrosive corrosion of the cap, rust inhibitors such as silicate and phosphate polymers are added to the water to coat the copper surface.
There is a method of forming a protective film of rust-preventing ingredients, but this protective film deteriorates in a short period of time and peels off, so it is necessary to periodically add rust-preventive agents, which is difficult to manage in ordinary households. There was a problem that.

However, the method of plating metals such as nickel and tin on the copper surface is difficult to achieve because nickel and tin are metals with a lower electric potential than copper when exposed to the highly corrosive water environment described above. In a water environment with strong water quality, the plating layer corrodes in a short period of time, and as a result of peeling and wear of the plating layer, the base metal, copper, corrodes.

Furthermore, a coating layer of organic and inorganic binders,
There are many pinholes in the coating layer itself, and fM eclipses to 1 through these pinholes, so the film thickness is reduced to 10
It is necessary to make the thickness considerably thicker, 0 μm or more, and as a result, there are problems such as a significant decrease in heat exchange efficiency.

OBJECT OF THE INVENTION The present invention solves such problems and provides long-term
The purpose is to prevent corrosion of heat exchangers that have copper heat transfer members and to improve the durability and reliability of the equipment.

Structure of the Invention The present invention consists of a copper heat transfer part made of paulownia wood, a binder made of acrylic resin, melamine wood, and epoxy 4FJIH, silicon carbide powder, and standard electrode potential. A coating layer is formed with a paint in which metal powder of V or less is dispersed (1), and a coating layer is further formed thereon with a binder made of an acrylic resin, a melamine resin, and an epoxy resin.

With this configuration, even if the heat exchanger is used in a highly corrosive water environment such as underground water, a two-layer coating layer is formed on the surface of the copper heat transfer member, preventing corrosion of the copper heat transfer member. It is possible to significantly suppress the timbre of water and towels caused by copper corrosion.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The figure is a partial sectional view of a heat exchanger showing an embodiment of the present invention. In the figure, 1 is a copper heat transfer member, with acrylic resin, melamine resin, and epoxy resin as binders on the surface that comes into contact with water, and silicon carbide powder applied to this as standard
A coating layer 2 is formed by heating and curing a paint to which metal powder with a small electrode potential of 0 V or less F is added, and this coating layer 2 contains silicon carbide powder 2a and metal powder 2b with a standard electrode potential of 0 V or less. is evenly distributed.

Further, on this coating layer 2, a binder made of a mixture of acrylic resin, melamine 41, and epoxy resin is applied and heated to form a coating layer 3.

In this configuration, coating layers 2 and 3 are made of acrylic resin and melamine resin used as binders, which are cured by heat, and their molecular structure is a three-dimensional dense network structure, making them impermeable to water molecules and corrosion factors. Because they are small and have a low glass transition point, the presence of these coating layers 2 and 3 makes it possible to minimize the number of pinholes.The existence of these coating layers 2 and 3 prevents corrosive factors, which exist in large quantities in underground water, from penetrating the copper heat transfer member 1. can be largely prevented.

However, since it is impossible to completely remove pinholes in both coating layers 2 and 3, the corrosion factor No. 11J slightly enters through these pinholes, but is present in coating layer 2. The standard electrode potential of metal powder 2b is. V or less, and the potential is lower than that of the copper heat transfer member 1, which is the base material, so the metal powder 2b enters the corrosion factor (!- selectively causes a corrosion reaction, and the corrosion factor enters the coating layer 2. Since the copper heat transfer member 1 is consumed in water, corrosion of the copper heat transfer member 1 is prevented, and copper ions are no longer eluted into the water.Also, since the coating layer 3 is present on the coating layer 2, this coating layer a
Since the amount of the corrosion factor passing through is small,
The loss of the metal powder 2b present in the coating layer 2 due to corrosion is small, and it is possible to prevent corrosion of the copper heat transfer part 4-A1 and production of copper ions into the water over a long period of time.

In addition, since silicon carbide powder 2a with good thermal conductivity is dispersed in the coating layer 2, the excellent thermal conductivity of copper is not impaired, and as a result, heat transfer from the copper heat transfer member to water is improved. High heat exchange efficiency can be achieved because the heat exchange efficiency is not impaired.

Furthermore, since epoxy resin is added to the coating layers 2 and 3, the adhesion between the copper heat transfer member 1 and the coating layer 2 can be significantly improved.8 Acrylic resin and melamine used in the coating layers 2 and 3 of the present invention The composition ratio of resin and epoxy resin is determined by weight ratio [Acrylic (Hugetsuji)/Melamine (Sogetsuji]) or [1 /1] ~ [110,7].

[Acrylic resin and melamine resin/epoxy resin] is [I
The range is preferably from [Ilo, 1] to [Ilo, 2.1.

On the other hand, examples of the residual powder 2b having a standard electrode potential of 0 V or less include aluminum, zinc, tin, nickel, and iron, and among them, aluminum, nickel, and tin are preferable because of their good corrosion resistance.

Effects of the Invention According to the heat exchanger of the present invention, since a two-layer coating with excellent corrosion resistance and thermal conductivity is formed on the surface of the copper heat transfer member, corrosion of the copper, which is the heat transfer member, is prevented. Since it can prevent the elution of copper ions, it can prevent water and towels from turning blue due to copper ions, and
Since corrosion of copper heat transfer members can be prevented for a long period of time and copper's excellent thermal conductivity is not impaired, it is expected that the durability and reliability of heat exchangers will be significantly improved.

[Brief explanation of the drawing]

The figure shows -r? of a heat exchanger which is an example of misfire 1. 16 is a sectional view. 2...Coating layer, 3...Coating layer, 2a...Silicon carbide powder, 2b...
...Metal powder.

Claims (1)

[Claims] A coating layer is formed on the surface of the copper heat transfer member with a paint in which silicon carbide powder and metal powder with a standard electrode potential of OV or less are dispersed in a binder made of acrylic resin, melamine resin, and epoxy resin, and then acrylic is coated on top of this. A heat exchanger with a coating layer formed with a binder made of resin, melamine resin, and epoxy resin.