JPS61221271A - Paint for identifying symbol marking of steel stock - Google Patents

Abstract

PURPOSE:To provide the title paint which can be applied over a temp. range of room temp. to high temp., has excellent adhesion and does not cause peeling even when exposed to wind and rain, containing Ca(H2PO4)2, Ca3(PO4)2, boric acid (salt) and optionally a rare earth element oxide. CONSTITUTION:5-50wt% Ca(H2PO4)2, 0.5-30wt% Ca3(PO4)2, 0.1-5wt% boric acid or borate (e.g. borax) and optionally not more than 10wt% (greater than 0%) rare earth element oxide (e.g. Ce2O3) are dispersed in water. If desired, further additives such as pigment (e.g. TiO2, Cr2O3, red iron oxide, cobalt blue or Chrome Yellow), thickner, surfactant, etc., are dispersed therein to obtain the title paint which can be used over a wide temp. range of room temp. to high temp. of max. 1,200 deg.C.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a paint used to mark identification symbols on steel products manufactured in steel works, etc. The present invention relates to a marking paint that can be used up to a high temperature range of 1200''C.

<Conventional technology and its problems> In recent years, steelworks have shifted from a mass production system to a high-mix, low-volume production system due to the production of high-value-added high-grade steel materials in addition to conventional ordinary steel materials. There is a strong desire to save energy by synchronizing and synchronizing processes, and for this reason, systemization through labor saving and continuous automation is being actively carried out.

Under these circumstances, intermediate products 1. Controlling each product individually is an important point for quality assurance. Identifying and displaying steel products for each product minimizes the occurrence of mixed materials, such as steel materials that flow through the main process, and steel materials that are removed from the main process, processed, and then rejoined and returned to the original process. It plays an important role in this.

In particular, the majority of steel pieces such as slabs and blooms manufactured by continuous casting equipment are directly transported to the next process, but some are inspected for surface flaws, removed, and cut. In order to do this, it is first cooled down to room temperature or a fairly low temperature.

In order to transport such steel materials to the next process, it is necessary to mark them again with identification symbols.

Conventional marking paints have a range of use depending on the temperature of the steel material, and are used depending on the temperature of the steel material to be marked, such as room temperature, medium temperature, or high temperature. Therefore, it was necessary to install several expensive marking devices depending on the temperature, install multiple paint supply devices and switch between them, or manually mark passing steel materials that were outside the range of use. . Because of this, humans intervene on automated lines, which can lead to errors.

There are also safety issues. In particular, the systematic connection between plants has been a major obstacle to continuous automation in facilities where steel materials ranging from room temperature to high temperature coexist.

In addition, conventional paints could only mark ordinary steel and carbon steel, but the paint of the present invention can mark nickel, chrome,
It has a strong affinity for metals other than low iron, and can be applied to nickel steel, chrome steel, stainless steel, and other alloys.

Conventional marking paints include: i) Paints from room temperature to 150°C, such as ordinary paints, emulsion paints, and inks, which cannot be used because they burn or decompose at high temperatures.

ii) Hot marking paints that can be sprayed mainly from 350°C to 600°C 1 For example, in Japanese Patent Publication No. 14285/1985, the paint film becomes baked at high temperatures and cannot be removed,
Cannot be used at temperatures below ℃. Also, it cannot be sprayed particularly at high temperatures.

1ii) Items that can be marked at temperatures between 150°C and 1100°C For example, in Japanese Patent Publication No. 53-23723, since it is for special purposes and washes off with water, it cannot be used for marking general steel materials that are water-cooled or left outdoors. It is.

There was no paint that could be sprayed at any temperature from room temperature to high temperature.

<Object of the invention> The object of the present invention is to be able to mark identification symbols on steel materials ranging from room temperature to high temperatures using one type of paint, that is, one marking device, and to allow the marked steel materials to be left outdoors. To provide a paint for marking steel identification symbols that does not run off or peel off even when exposed to rain and wind.

<Structure of the Invention> The present invention comprises monocalcium phosphate 5 to 50 wt%, tertiary calcium phosphate 0.5 to 30 wt%, boric acid or borate 0
．． The present invention provides a paint for marking identification symbols for steel materials, characterized in that it contains 1 to 5 wt%.

The present invention also provides monocalcium phosphate 5 to 5 wt%, tribasic calcium phosphate 0.5 to 30 wt%, boric acid or borate salt 0.1 to 5 wt%, and up to 10% (excluding 0%). The present invention provides a paint for marking identification symbols on steel materials, which is characterized by containing a rare earth oxide.

The paint for marking steel identification symbols of the present invention will be explained in more detail below.

The paint of the present invention contains monobasic calcium phosphate 5-5゜w, t%.
Disperse 0.5 to 30 wt% of tricalcium phosphate, 0.1 to 5 wt% of boric acid or borate, and 10% or less (not including 0%) of rare earth oxides in water, and further mix and disperse pigments, etc. It was used as a paint.

Next, the effects of each component will be explained.

Monocalcium phosphate and tricalcium phosphate are dissolved or dispersed in water in an equilibrium state, but when applied to the surface of steel, they react with iron and form a phosphate film that is insoluble in water. . At this time, pigments and other components come together to form a strong surface film that adheres to the steel material. For this reason, even if paint is applied at room temperature, once it dries, it becomes a film that does not wash off even under water.

The paint of the present invention contains 5 to 5% by weight of monobasic calcium phosphate. If this is less than 5wt%, the adhesion will be poor and the
If it exceeds 50 wt%, heat resistance will deteriorate.

Further, the content of tricalcium phosphate is 0.5 to 30 wt%. If this is less than 0.5 wt%, heat resistance will deteriorate.

If it exceeds 30 wt%, paint will clog in nozzles, etc.

Next, we will discuss boric acid or borates in paints. This has the effect of improving the adhesion of the paint when sprayed onto steel materials at a temperature of 100°C or higher.

Normally, when a water-based paint is sprayed on a steel material at a temperature of 100°C or higher, the water evaporates instantly on the surface, so the higher the temperature, the more the water is blown off the surface of the steel material and the paint does not adhere to the surface of the steel material.However, the paint of the present invention is instantly attached to the steel surface without being repelled due to the presence of calcium phosphate solution and borate. Moreover, the higher the temperature of the steel, the stronger the adhesive force of the paint.

It is preferable that at least one of boric acid or borate be contained in the paint in a total amount of 0.1 to 5 wt%. If this is less than 0.1 wt%, the adhesion will be poor.

Moreover, if it exceeds 5 wt%, the surface of the coating film will be disturbed and the nozzle etc. will be clogged.

Furthermore, by adding a small amount of rare earth oxide.

It can form adhesive coatings not only on carbon steel, but also on nickel steel, chrome steel, stainless steel, alloy steel, etc.

Rare earth oxides have a strong affinity with nickel, chromium, and other alloy components, and at high temperatures they partially penetrate into the alloy components and are partially reduced to form a strong sintered layer, resulting in strong VI adhesion of the coating film. Even when the steel material cools, it does not peel off and becomes a clear identification mark.

Rare earth oxides include cerium oxide, lanthanum oxide,
Neodymium oxide, samarium oxide and mixtures thereof are used. The rare earth oxide is preferably added to the paint in an amount of 10% or less, because if it exceeds 10%, heat resistance and adhesion will deteriorate.

As the borate, boric acid, borax, sodium borate, potassium borate, lithium borate, etc. are used.

As the pigment, titanium sulfide, chromium oxide, red iron oxide, cobalt blue, chrome yellow, titanium yellow, etc. are used. The appropriate pigment content in the paint is 5 to 30 wt%.

In addition, small amounts of anti-settling agents such as bentonite, montmorillonite, clay clay, and other clays may be added to the paint, and viscosity modifiers such as carboxymethyl cellulose, hydroxyethyl cellulose, sodium alginate, The thickener may be used in a small amount, the low dispersion agent, and the surfactant may be used in small amounts, and the purpose of the paint is to use them to the extent that they do not adversely affect the effects of the present invention. You can use it accordingly.

EXAMPLES> Next, the present invention will be specifically explained with reference to examples. A formulation example is shown in Table 1. The thus-blended mixture was mixed and dispersed in a ball mill for about 20 hours to prepare a paint.

(Example 1) Paints prepared as described above (formulation examples 1 to 4) were applied to steel (SS41.345C) at room temperature using a stencil (loft number display board with numbers etc. punched out on paper or metal plate). After spraying the numbers, the paint dried after about 30 minutes, so
The paint (mark) could not be removed even if the steel material was soaked in water or washed away.

(Example 2) Steel material (SS41.545C) at 500℃.

After heating to various temperatures such as 900° C. and 1200° C., markings were made by spraying the paint, but the marks were clear and the paint did not peel off even after cooling in air or quenching with water.

(Example 3) Even when the paints of Formulation Examples 1 to 3 were sprayed onto 18% chrome steel at 600°C, the same marks were clear and the paints could not be removed even after air cooling and rapid cooling.

(Example 4) High nickel steel was marked with the paint of Formulation Example 1 at 1100°C, but the results were the same as in the previous example.

<Effects of the Invention> As described above, the paint of the present invention can be applied at any temperature from room temperature to high temperature, which could not be achieved with conventional paints, and it adheres well even when sprayed at any temperature, and does not adhere even when sprayed with water. You will get a mark that will not run off or disappear.

In addition, it can be applied to ordinary steel, carbon steel, special steel such as stainless steel, and alloys, making it possible to make markings that will not peel off.

Applications include not only marking continuously cast steel billets, but also marking thick plates after rolling and hot coils.

It can be used for product identification in cold-rolled coil, coolant, and lot number processing processes.

Using the paint of the present invention, a single automatic marking device can mark any type of steel or steel piece at any temperature, and the applied marks will not disappear even if left outside for a long time. This eliminates mistakes in sorting and rolling of steel billets, which greatly contributes to improving yields and saving resources.

Claims (2)

[Claims] (1) Monocalcium phosphate 5-50 wt%, tertiary calcium phosphate 0.5-30 wt%, boric acid or borate 0.1
A paint for marking steel identification symbols, characterized in that it contains ~5 wt%. (2) Monobasic calcium phosphate 5-50 wt%, tertiary calcium phosphate 0.5-30 wt%, boric acid or borate 0.1
A paint for marking steel identification symbols, characterized by containing ~5 wt% and 10% or less (excluding 0%) of rare earth oxides.