JPS6289775A - Coating and reflector coated therewith - Google Patents

Abstract

PURPOSE:To obtain a coating capable of giving coating film suitable for electrical radiation-receiving reflectors, outdoor illumination reflectors, etc., by formulating an alkali metal silicate and a phosphate in specified proportion. CONSTITUTION:The objective coating can be obtained by formulating (A) 100pts. wt. of an alkali metal silicate (pref. a product prepared by incorporating 100pts. wt. of silica colloid with 5-20pts.wt. of a metallic oxide such as potassium oxide followed by treatment on heating in an alkaline state) and (B) 0.1-10pts. wt. of a phosphate (e.g., multivalent metallic salt, ammonium salt, or organic amine salt of phosphoric acid). This coating is cured through baking at 150-200 deg.C to form a coating layer, thus obtaining the other objective reflector.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a reflector used for radio wave receiving reflectors used in communication equipment, electrical equipment, etc., outdoor lighting reflectors, etc., and a paint applied thereto. .

[Background technology]

Traditionally, reflective plates used for radio wave reception and outdoor lighting reflectors are made of iron, aluminum, reinforced plastic with a metallized reflective layer, etc., but these are all used outdoors. It had shortcomings in rust resistance and scratch resistance. For this reason, attempts have been made to coat the surface of the reflector with organic paints such as silicone resin and fluororesin, or Cefmic vapor deposition, but the former has drawbacks in heat resistance, weather resistance, and corrosion resistance, and the latter has disadvantages in heat resistance, weather resistance, and corrosion resistance. This method has disadvantages in that it cannot be applied to reflectors with complicated structures, has poor workability, and requires a large amount of cost. In order to solve these problems, attempts have been made to coat with inorganic paints such as alkali silicate; for example, in Japanese Patent Publication No. 56-30521, an alkali silicate solution is applied to an aluminum substrate and heated at 249 to 482°C.
Thereafter, a method is provided in which the alkali metal contained in the film is extracted with an inorganic acid solution, and in JP-A-52-52135, after applying an alkali silicic acid solution to the surface of a metal plate such as aluminum, the temperature is below 50°C. After drying with 240~2
Baking at 70°C was proposed, followed by treating the product with acid and water and then repeating the above steps, but in both cases the baking temperature was high (over 240°C), causing damage to the metal plate and energy usage costs. There was a problem with the rise and burning of the furnace conut. Furthermore, in JP-A No. 41-24446, by removing almost all the alkali metal ions in the film, the metal ions react with carbonate in the air over time to produce carbonate, which makes the surface of the reflector plate cloudy and reflects light. Although a method has been proposed to prevent a large decrease in the coefficient of thermal expansion, there is a problem that cracks occur due to a decrease in mechanical strength and a decrease in the coefficient of thermal expansion. Showa 54
JP-A-54481 provides a method for controlling the amount of alkali metal ions in the coating, but it is not satisfactory as it has advantages and disadvantages in terms of clouding of the coating, reduction in strength, and cracking.

[Purpose of the invention]

The objectives of the present invention are rust resistance, scratch resistance, corrosion resistance,
To provide a paint with excellent weather resistance and a reflector coated with the paint.

[Disclosure of the invention]

The present invention provides a paint characterized by adding 0.1 to 10 parts of a phosphate to 100 parts by weight of an alkali metal silicate (C or less), and a reflective plate coated with the paint, which has rust resistance. , it was possible to obtain a paint with excellent scratch resistance, corrosion resistance, and weather resistance, and by baking the paint on a reflector under specific conditions, it was possible to impart the above performance to the reflector.Hereinafter, the present invention Detailed explanation of.

The alkali metal silicate used in the present invention is preferably one or more selected from the group consisting of potassium oxide, sodium oxide, calcium oxide, magnesium oxide, aluminum oxide, zinc oxide, and lithium oxide, based on 100 parts of hydrous silica colloid. is added with 5 to 20 parts of metal oxide and heat-treated in an alkaline state, preferably phosphoric acid (polyvalent) per 100 parts of the alkali metal silicate.
Phosphates such as metal salts, ammonium salts, organic amine salts, etc. 0
．． A paint is obtained by adding 1 to 10 parts. That is,
This is because if the phosphate content is less than 0.1 part, the whitening resistance will be reduced, and if it exceeds 10 parts, the pot life of the paint will be reduced. The hydrous silica colloid preferably has a particle size of 10 to 10 microns and a viscosity of 200 to 300 Cps (1) -(
1) It is desirable to use a sulfuric acid colloid. As the material of the reflector, iron, aluminum, or reinforced plastic made into the shape of a reflector can be used, and the material is not particularly limited, and the shape is also limited. The paint according to the present invention can be applied to the base reflector by any means such as coating, dipping, casting, spraying, or transfer.
The coating layer is formed by baking and hardening to obtain a reflecting plate. At this time, it is preferable to simply pickle or wash the coated surface after baking and hardening to remove alkali metal salts containing alkali metal phosphates and carbonates slightly precipitated on the coated surface. . The coating may be applied once, but the performance can be further improved by repeating the coating several times. The thickness of the coating layer is preferably 0.5 to 10 microns, more preferably 1 to 5 microns. That is, if it is less than 0.5 microns, pinholes tend to occur and the corrosion resistance decreases, and if it exceeds 10 microns, blisters and cracks tend to occur in the corrugated film during bake hardening. The paint of the present invention becomes colorless and transparent after curing by baking, and its coloring is arbitrary and not particularly limited. The present invention will be specifically explained below using examples.

Example To 100 parts of hydrous silica colloid with a viscosity of 250 Cpi, 4 parts of potassium oxide, 0.1 part of magnetic oxide, 0.1 part of zinc oxide, 0.7 parts of lithium oxide, and 0.1 part of aluminum oxide were added. An alkali metal silicate was obtained by heating at 70 to 80°C for 70 hours at pH 10-12, and 2 parts of ammonium phosphate was added to 100 parts of the alkali metal silicate to obtain a paint. Next, spray paint the paint onto the aluminum reflector base so that the coating thickness after baking and hardening is 3 microns, pre-dry it at 100°C for 5 minutes, and then bake at 150-200°C for 10 minutes. After that, it was pickled with a 2% nitric acid solution at room temperature for 3 minutes, and then washed with water for 3 minutes, and then dried to obtain a colorless and transparent reflector having a layer.

Conventional example: 400 to 450 using commercially available alkali silicate inorganic paint
A reflecting plate was obtained in the same manner as in the example except that it was baked at ℃.

〔Effect of the invention〕

As is clear from Table 1, the performance of the reflective plates of the embodiment and the conventional example is that the performance of the reflector coated with the paint of the present invention is good, and the reflector coated with the paint of the present invention is superior. It was confirmed.

Chapter 1 Table

Claims (5)

[Claims] (1) A paint characterized in that 0.1 to 10 parts by weight of a phosphate is added to 100 parts by weight of an alkali metal silicate. (2) Hydrous silica colloid containing alkali metal silicate 10
Adding 5 to 20 parts by weight of metal oxide to 0 parts by weight,
The paint according to claim 1, which is heat-treated in an alkaline state. (3) The metal oxide is potassium oxide, sodium oxide, calcium oxide, magnesium oxide, aluminum oxide,
The coating material according to claim 1 or 2, characterized in that the coating material is one or more selected from the group consisting of zinc oxide and lithium oxide. (4) The paint according to claim 1, wherein the phosphate is a (polyvalent) metal salt, ammonium salt, or organic amine salt of phosphoric acid. (5) Paint containing 0.1 to 10 parts by weight of phosphate to 100 parts by weight of alkali metal silicate on the surface.
A reflective plate comprising a coating layer baked and hardened at 200°C.