JPH0987065A - Urethane resin emusion coating material and refractory brick - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the function of a coating film to absorb expansion of magnesia carbon brick with a relatively this coating film, by applying a specified urethane resin emulsion coating material on the surface of the brick. SOLUTION: This urethane resin emulsion coating material is prepared by compounding a urethane resin emulsion as the main component and an org. granular material which completely combusts when exposed to air at high temp. The urethane resin emulsion coating material is applied to form a coating film having <=0.8mm thickness on the surface of magnesia carbon brick to obtain refractory brick. The surface of the coating film of the obtd. refractory brick is rough and has an enough effect to prevent slipping in the process for production or building a furnace so that safeness of work can be improved. Since the org. granular material is removed by combustion during heating, the coating film can largely be shrunk in its film thickness. Thus, the thin film gives a high expansion-absorbing function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based urethane resin coating material and a refractory brick, and more particularly to a magnesia carbon brick having a coating film formed from the water-based urethane resin coating material.

[0002]

2. Description of the Related Art Conventionally, basic refractory bricks such as calcined magnesia-domite bricks and magnesia carbon bricks have been used as refractory bricks used in furnace constructions such as converters and pots. Since these basic refractory bricks generally have a high coefficient of thermal expansion, it is necessary to absorb the expansion after furnace construction. In the case of fired magnesia-domite brick, it was used by being impregnated with tar in order to impart digestion resistance (a powdering phenomenon due to CaO in the brick), and after impregnating tar, it was adhered to the surface with a thickness of about 1 mm The tar layer is used as an expansion absorber after furnace construction.

However, since the fired magnesia-domite brick has a lower durability as compared with the magnesia carbon brick, magnesia carbon bricks having a higher durability are used more and more today. Usually, in the magnesia carbon brick, a metal powder is added to impart oxidation resistance, and this metal powder reacts with the carbon contained in the brick at the time of heating to generate a substance having a large thermal expansion, New coating materials to replace tar are needed.

Further, since the magnesia carbon brick contains a large amount of carbon, the surface is slippery, and a coating material as an anti-slip material is required for ensuring safety during manufacturing and furnace construction. . It was also tried to apply tar to magnesia carbon brick as a coating material having a function as an expansion absorbent and a non-slip material, but the magnesia carbon brick, which is a carbon-containing refractory, is difficult to apply to tar,
There is a problem that the same film thickness cannot be obtained on the front and back planes and side surfaces.

[0005]

Therefore, it has already been proposed to apply a synthetic resin, a natural resin or a mixture thereof to the surface of a brick. In this case, the film thickness formed on the surface of the brick is compared. It is very small and it is difficult to obtain a film thickness of 0.5 mm or more. Therefore, depending on the material of the brick, the function as an expansion absorber becomes insufficient, and cracking may occur. Further, in order to enhance the expansion and absorption function, it has been attempted to apply a coating material again after coating and drying to increase the film thickness to, for example, about 2 mm. In this case, it takes a lot of time and labor to form the coating layer. It takes time and
Brick may fall off when the furnace is tilted due to excess absorber.

Further, in the case of a synthetic resin, the one in which an organic solvent is used as a solvent has problems in environmental pollution due to volatilization of the organic solvent, influence on human body, and inflammability. Further, in the case of an emulsion-based water-based resin, the above problem does not occur, but when the resin Tg is low, the coating film forming property is good, but blocking occurs when the coated objects are stacked. When Tg is increased, it is excellent in terms of blocking, but the film-forming property at low temperature is poor, and when a film-forming auxiliary is added to improve the film-forming property, blocking occurs.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventor has found that a relatively thin film can be obtained by applying a specific water-based urethane resin coating material on the surface of magnesia carbon brick. It has been found that a large thickness can exert a large expansion and absorption function, and the present invention has been completed.

That is, the present invention is as follows (1) and (2). (1) A water-based urethane resin coating material comprising a water-based urethane resin as a main component and an organic granule that completely burns when exposed to air at a high temperature. (2) A refractory brick obtained by applying the aqueous urethane resin coating material according to (1) to the surface of a magnesia carbon brick to form a coating film having a thickness of 0.8 mm or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an aqueous urethane resin is used as a resin constituting the main component of a coating material.
As the water-based urethane resin, any of anion, nonion and cation can be used. Blends of these can also be used. As the isocyanate component and the polyol component used in the water-based urethane resin, all known ones can be used, but from the viewpoint of economy, particularly preferable ones include tolylene diisocyanate (mixture of isomers). ), Diphenylmethane diisocyanate (including a mixture of isomers and polynuclear compounds), and the like, and examples of the latter include various polyether polyols and polyester polyols.

Further, a blend of an aqueous urethane resin and an aqueous or water-dispersion type resin such as an acrylic emulsion or a vinyl acetate emulsion can also be used. A curing agent (urethane, epoxy, aziridine, carbodiimide, melamine resin, etc.) can be used in combination with the aqueous urethane resin or blend. Of course, an oxidative polymerization type aqueous urethane resin can also be used. Further, the organic granules added to the resin are not particularly limited as long as they are completely combusted when exposed to air at a high temperature, and for example, pitch powder, sawdust and the like can be used.

As a method for forming the coating film on the surface of the magnesia carbon brick, it is applied by a brush, a roller, a spatula or a spray, or a liquid is adhered to the surface of the brick by a known method such as dipping, and then, The method of drying is adopted. Since this liquid contains water-based urethane resin as the main component, it has good wettability with the magnesia carbon brick, which is a carbon-containing brick, and also has excellent film-forming properties, drying properties, abrasion resistance, and blocking properties. It is possible to make the film thickness of the plane and the side surface of the film uniform.

The film thickness of the coating film can be freely changed within a range of 0.8 mm or less by increasing or decreasing the amount of organic granules added. Although it is technically possible to make the film thickness thicker than 0.8 mm, if the film thickness exceeds 0.8 mm, bricks may fall off due to excess absorber when the furnace body tilts, which is not preferable. The surface of the brick having such a coating film is rougher than the surface of the magnesia carbon brick having no coating film, and is less likely to slip. In addition, since the organic granules are completely combusted and removed during heating, and the amount of shrinkage with respect to the film thickness of the coating film increases, a large expansion can be absorbed with a thin film thickness. Therefore, the film thickness is set to 0.
By adjusting it to 8 mm or less, it will be possible to absorb the expansion corresponding to the material, expansion absorption will be insufficient and cracks will occur, or bricks will fall out when the furnace body is tilted due to excessive absorption material. Can be prevented.

[0013]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 2000 equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen introducing pipe
In a ml four-necked flask, 86.5 g of polypropylene glycol having a molecular weight of 2000 and neopentyl glycol 5
3.4 g, trimethylolpropane 4.3 g, dimethylolpropionic acid 17.9 g and N-methyl-2-pyrrolidone 34.5 g were charged, and the temperature was raised to 90 ° C. while introducing nitrogen to dissolve the contents. . Next, the mixture was cooled to 40 ° C., 72.0 g of acetone was added, and then 137.8 g of tolylene diisocyanate was added dropwise over 1 hour. Inner temperature 40 ~
After the reaction was carried out at 50 ° C. for 8 hours, acetone 100.
Diluted with 5 g. NC of the obtained urethane prepolymer
The O group content was 0.90%.

504.4 g of deionized water containing 10.7 g of dimethylethanolamine was kept at 40 ° C., and 506.9 g of the above urethane prepolymer was added dropwise thereto to carry out hydration and chain extension reaction to obtain an aqueous urethane resin. A solution was obtained. This aqueous urethane resin solution was further deaerated under reduced pressure at 40 ° C. to obtain an anionic, self-emulsifying aqueous urethane resin having a resin content of 38.0%, PH 7.6, and a viscosity of 200 CP / 25 ° C. 65.2 g of the obtained aqueous urethane resin
, Granular pitch (volatile content 45-55%, fixed carbon 45
~ 55%, 1% ash content particle size 0.3mm or less 9
27.9 g (of 0% or more) and 6.9 g of sawdust (0.5 mm or less) were mixed to obtain an aqueous urethane resin coating material.

Example 2 2000 equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen introducing pipe
In a ml four-necked flask, XP1077E (transesterified polyol of linseed oil and pentaerythritol, molecular weight 638, iodine value 133, manufactured by Mitsui Toatsu Chemicals, Inc.) 11
5.4 g, molecular weight 2000 polytetramethylene ether glycol 71.2 g, trimethylol propane 5.
8 g, dimethylolpropionic acid 21.5 g and N-methyl-2-pyrrolidone 34.4 g were charged and the temperature was raised to 90 ° C. while introducing nitrogen to dissolve the contents. Next 40 ° C
After cooling, 86.5 g of acetone was added and then 86.2 g of tolylene diisocyanate was added dropwise over 1 hour.
The reaction was carried out for 8 hours while keeping the internal temperature at 40 to 50 ° C, and then diluted with 86.5 g of acetone. The NCO group content of the obtained urethane prepolymer was 0.90%.

485.0 g of deionized water containing 12.1 g of dimethylethanolamine was kept at 50 ° C. and 507.5 g of the above urethane prepolymer was added dropwise to carry out hydration and chain extension reaction to obtain an aqueous urethane resin solution. It was This aqueous urethane resin solution was further subjected to vacuum deacetoneation at 40 ° C. to obtain a resin content of 38.0%, PH 7.6, and a viscosity of 400 CP.
An anionic, self-emulsifying, oxidative polymerization type aqueous urethane resin of / 25 ° C. was obtained. 95.0 g of this aqueous urethane resin,
An oxidation polymerization catalyst (DICNATE 3111, manufactured by Dainippon Ink and Chemicals, Inc.) (1.8 g) and sawdust (0.5 mm or less) (5.0 g) were mixed to obtain an aqueous urethane resin coating material.

Example 3 The water-borne urethane resin coating material obtained in Example 1 was applied to a molded magnesia carbon brick for a converter with a roller to a thickness of about 0.6 mm, and then dried at a predetermined temperature to brick. A coating film was formed on the surface to obtain the refractory brick of the present invention. Example 4 The water-based urethane resin coating material obtained in Example 2 was applied to a molded magnesia carbon brick for a converter with a roller to a thickness of about 0.6 mm, and then dried at a predetermined temperature to apply it to the brick surface. A film was formed to obtain a refractory brick of the present invention.

The surfaces of the coating films formed in Examples 3 and 4 were rough and slip-resistant. Obtained refractory bricks,
That is, 180 magnesia carbon bricks coated with a coating film
When the entire area was applied to the narrowed portion of the t converter, it was confirmed that the thrust up due to the thermal expansion of the bricks in the furnace abdomen was absorbed and the conventional cracking phenomenon was eliminated. Furthermore, when this refractory brick was used in an actual furnace, the coating film absorbed 1/3 of the coefficient of thermal expansion of the lining brick, and the brick did not fall off when the furnace body was tilted due to excess absorber, and cracking did not occur. The good result that it does not occur was obtained.

[0020]

As described above, since the coating material used in the present invention is mainly composed of the water-based urethane resin, the wettability with the magnesia carbon brick which is a carbon-containing brick is high,
A coating film can be uniformly formed on the entire surface of a magnesia carbon brick. Further, since the coating material is mainly composed of a water-based urethane resin and contains organic granules, the surface of the coating film formed on the brick surface is rough, and it is possible to sufficiently prevent slippage during manufacturing or furnace construction. Therefore, the safety of work can be improved. Further, since the present invention uses a coating material containing an organic granule that completely burns when exposed to air at a high temperature, the organic granule burns and is removed during heating to increase the film thickness. When the furnace body is tilted due to excess absorber, the thickness of the coating film can be reduced to prevent the occurrence of a cracking phenomenon. It is possible to prevent the phenomenon of brick falling out. In addition, according to the present invention, the film thickness of the coating film is adjusted to 0.8 m by adjusting the blending ratio of the organic granules of the coating material.
It can be arbitrarily adjusted at m or less. In particular, in view of the fact that the coefficient of thermal expansion of a magnesia carbon brick, which is improved every day, varies depending on the material, the present invention is capable of adjusting the film thickness according to the coefficient of thermal expansion of the material. Since it can be applied to carbon bricks, it is extremely useful in extending the life of the furnace.

Claims (2)

[Claims] 1. A water-based urethane resin coating material comprising a water-based urethane resin as a main component, and an organic granule that completely burns when exposed to air at a high temperature. 2. A water-based urethane resin coating material according to claim 1 is applied to the surface of a magnesia carbon brick to give a thickness of 0.8 m.
A refractory brick obtained by forming a coating film of m or less.