JP2006233135A - Aqueous resin coating agent and refractory brick obtained by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous resin coating agent which can easily form a coating having a uniform thickness, is less prone to thermal stress cracking, excels in anti-slip properties, particularly hardly peels even when handled under severe conditions such as the transportation of bricks having the coating, and can retain excellent adhesiveness, and a refractory brick obtained by using the above aqueous resin coating agent. <P>SOLUTION: The aqueous resin coating agent has an aqueous polyurethane resin (A), an acrylic resin emulsion (B), a latex (C), and an inorganic filler (D) as essential components and comprises, based on the total solid content of the coating agent, 5-40 mass% aqueous polyurethane resin (A), 5-40 mass% acrylic resin emulsion (B), 5-40 mass% latex (C), and 40-85 mass% inorganic filler (D). The refractory brick is obtained by applying the above aqueous resin coating agent on a magnesia carbon brick. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an aqueous resin coating agent containing an aqueous polyurethane resin, an acrylic resin emulsion, latex, and an inorganic filler, and a refractory brick using the same.
More specifically, the water-based resin coating is extremely effective in preventing peeling from the brick surface during line transportation when manufacturing brick because it has excellent anti-slip and anti-slip properties, and particularly excellent adhesion to the brick surface. The present invention relates to a refractory brick using the agent and the water-based resin coating agent.

Conventionally, as refractory bricks used for the inner walls of molten metal containers such as converters, kneading wheels and ladles, graphite-containing refractory bricks such as alumina carbon bricks or magnesia carbon bricks (MgO-C bricks) are often used. ing.
This graphite-containing refractory brick is used in many kilns because it has a high graphite content and is excellent in slag resistance and spalling resistance. It was very slippery, and there was a risk of dropping during manufacturing and construction.

On the other hand, since the magnesia carbon brick has a larger coefficient of thermal expansion as the content of magnesia increases, there is a problem that a problem of so-called “scratch” is likely to occur due to heating.
For this reason, it is extremely important for quality control to prevent “slip cracks” caused by the thermal expansion of bricks during preheating of the furnace or at the beginning of operation (for example, the furnace temperature reaches as high as about 1650 ° C.). There were methods such as thickening the layer of paint applied to the brick surface, and absorbing the expansion allowance of the brick as the paint itself disappeared to some extent when the furnace heated up. The effect was not obtained.

Various proposals have been made to solve this problem.
For example, an aqueous polyurethane resin coating material mainly containing an aqueous polyurethane resin, which is obtained by containing organic granules such as pitch powder and sawdust that completely burns when exposed to air at high temperatures, and the aqueous polyurethane resin coating material There has been proposed a refractory brick (see, for example, Patent Document 1) obtained by coating a surface of magnesia carbon brick and forming a coating film. Such a water-based polyurethane resin coating material has good wettability with magnesia carbon brick, can form a coating film uniformly, and contains organic granules, so the surface of the coating film formed on the brick surface is rough. It is said that it is effective for preventing slippage during manufacturing and building a furnace.
However, such a water-based polyurethane resin coating material has a problem in that the compatibility between the water-based urethane resin and the organic granules is poor, and the painted surface of the brick is too rough, so that sufficient adhesion to the brick surface cannot be obtained.

Also, a refractory brick comprising, as a basic component, a resin liquid obtained by pasting vinyl acetate, phenol resin, epoxy resin, acrylic resin or the like with a solvent or a dispersion medium, and containing organic granules and / or organic fibers and carbonate. Coating materials (see, for example, Patent Document 2) have also been proposed. This coating material for refractory bricks is effective in preventing shrinkage of the refractory bricks by suppressing the shrinkage of carbonate against the rapid contraction caused by the burning and extinguishing of organic granules and / or organic fibers in the low temperature region. That's it.
However, such a coating material for refractory bricks has a large environmental impact because it uses a solvent, etc., and organic granule and organic fiber blends are poorly compatible with such resins, and the painted surface of the brick is also extremely rough. However, there was a problem that the adhesiveness with the brick surface could not be sufficiently obtained and the practicality was inferior.

Further, a coating material for heat-sealing to a preheated brick surface, which is a coating material for a carbon-containing brick (for example, a mixed powder of a low melt flowable resin and a high melt flowable resin selected from polyethylene or ethylene copolymer resin (for example, , See Patent Document 3). Such a coating material for carbon-containing brick is a powder, and is said to be able to form an anti-slip effect and a good film by powder coating such as electrostatic coating.
However, the coating film applied using such a carbon-containing brick coating material is thick, takes time and labor to form the coating film, and over-absorbing layers cause bricks to fall off when the furnace body tilts. However, there are many problems such as that excessive energy cost is required for electrostatic coating, and that adhesion is poor because nonpolar polyethylene is used.

In actual furnace construction, the brick handling conditions are very harsh, and the paint on the brick surface is exposed to a state where it is easy to peel off. Since the magnesia carbon brick is very heavy, for example, 20 to 60 kg, the coating agent may be peeled off when the bricks are rubbed against each other at the time of taking out from the pallet or during the building operation. Furthermore, in recent years, automation of furnace construction has progressed, and bricks can be transported by a conveyor or handled by a machine, but at this time, there is a problem that the coating agent is peeled off due to rubbing between the brick and the conveyor or handling by the machine. is there.
For this reason, it is an indispensable required performance for the coating agent that it is difficult to peel off. This is because if the coating agent is peeled off, the residue of the peeled coating agent partially adheres to the surface of the brick, creating thick and thin portions, resulting in “thickness unevenness” and uniformity in thickness. It is because it will be damaged. If the thickness is not uniform, expansion and absorption of the refractory brick in use will be insufficient, and the durability of the brick will decrease due to problems such as cracks, etc. There was no current situation.
JP 9-87065 A JP-A-5-330953 JP-A-8-157748

  As described above, from the viewpoint of safety, quality control, and the like, development of a novel coating agent that can solve the above problems and refractory bricks using the same has been desired.

  The purpose of the present invention is to make it easy to paint with a uniform thickness, hardly cause cracks, and has excellent anti-slip properties, and in particular, there is almost no peeling even when handled under harsh conditions such as conveyance of bricks, and excellent adhesion It is in providing the water-based resin coating agent which can hold | maintain, and the firebrick which uses the said water-based resin coating agent.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention include an aqueous polyurethane resin (A), an acrylic resin emulsion (B), a latex (C), and an inorganic filler (D) as essential components. By using a water-based resin coating agent, uniform thickness can be easily applied, and it has excellent anti-slip and anti-slip properties, and there is almost no delamination even when handled under harsh conditions such as brick transportation. The present inventors have found that the above problem can be greatly improved and have completed the present invention.

  That is, the present invention is an aqueous resin coating agent comprising an aqueous polyurethane resin (A), an acrylic resin emulsion (B), a latex (C), and an inorganic filler (D) as essential components, and the aqueous resin coating agent 5-40 mass% of aqueous polyurethane resin (A), 5-40 mass% of acrylic resin emulsion (B), 5-40 mass% of latex (C), and inorganic filling with respect to the total solid content weight in the inside An aqueous resin coating agent characterized by containing the agent (D) in the range of 40 to 85% by mass.

  In addition, the present invention provides a refractory brick characterized by applying the water-based resin coating agent on a graphite-containing brick.

  The present invention also provides a refractory brick characterized by applying the water-based resin coating agent on a magnesia carbon brick.

The water-based resin coating agent of the present invention can be easily applied with a uniform thickness, is less prone to cracking, has excellent anti-slip properties, and has almost no peeling even when handling bricks under harsh conditions such as work transportation. Excellent adhesion can be maintained.
Also, by increasing the hardness of the coating agent itself and improving the adhesion to the brick, it is possible to significantly improve the peeling from the surface of the brick in the transfer work of refractory bricks during the construction of the furnace, and there is virtually no peeling. The refractory brick can be constructed in the state, and the joint joint thickness between the bricks used for expansion and absorption of the used brick can be made uniform.

  In addition, the refractory brick using the water-based resin coating agent of the present invention has excellent anti-slip and anti-slip properties, and particularly excellent adhesion to the brick surface. Separation can be greatly improved, the occurrence of defective products is almost eliminated, and a great effect can be achieved in terms of quality control.

  The matters necessary for carrying out the present invention are described below.

[Water-based resin coating agent]
The aqueous resin coating agent of the present invention comprises an aqueous polyurethane resin (A), an acrylic resin emulsion (B), a latex (C), and an inorganic filler (D) as essential components.

First, the water-based polyurethane resin (A) that is the first component of the water-based resin coating agent of the present invention will be described below.
The polyurethane resin (A) is obtained by using polyisocyanate and polyol, and polyamine or low molecular weight glycol as a chain extender for increasing the molecular weight.

  The polyisocyanate used when preparing the aqueous polyurethane resin (A) is a compound represented by the following general formula [I].

R (NCO) n [I]
(In the general formula [I], R represents an arbitrary divalent organic group, and n ≧ 2.)

  As the polyisocyanate represented by the general formula [I] used for the preparation of the polyurethane resin (A), any conventionally known polyisocyanate can be used. For example, 1,4-tetramethylene diisocyanate, 1,6- Hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- or 1,4-diisocyanate, 1-isocyanate-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (also known as isophorone diisocyanate; abbreviation IPDI ), Bis- (4-isocyanatocyclohexyl) methane (abbreviation: hydrogenated MDI), 2- or 4-isocyanatocyclohexyl-2'-isocyanatocyclohexylmethane, 1,3- or 1,4-bis- (isocyanatemethyl). ) -Cyclohexane, bis- (4-isocyanate-3-methylcyclohexyl) methane, 1,3- or 1,4-α, α, α'α'-tetramethylxylylene diisocyanate, 2,4- or 2,6 -Diisocyanate toluene, 2,2'-, 2,4'- or 4,4'-diisocyanate diphenylmethane (abbreviation: MDI), 1,5-naphthalene diisocyanate, p- or m-phenylene diisocyanate, xylylene diisocyanate or And diphenyl-4,4′-diisocyanate. Of these, aromatic diisocyanate is particularly desirable from the standpoint of excellent mechanical strength, and aliphatic or alicyclic diisocyanate is particularly desirable from the standpoint of durability and light resistance. These polyisocyanates may be used alone or in combination of two or more.

Further, as the compound represented by the general formula [I], a polyisocyanate having more than two functions may be used in combination as long as the adhesiveness is not inhibited.
Examples of polyisocyanates having more than two functionalities that can be used in the present invention include 1,6-hexamethylene diisocyanate trimer, triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, lysine ester triisocyanate, 1, Examples include 6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyl octane, 1,3,6-hexamethylene triisocyanate.

  In the aqueous polyurethane resin (A), the isocyanate group content relative to the final polyurethane resin solid content is preferably in the range of 8 to 25% by mass. If the isocyanate group content relative to the final polyurethane resin solid content is within such a range, the cohesive force of the urethane molecules will be a suitable magnitude.

As the high molecular weight polyol used for preparing the aqueous polyurethane resin (A), in addition to the polyester polyol, for example, a polyether polyol, a polycarbonate polyol, etc., or a single or a mixture or a copolymer thereof may be used. .
In the case of using a polyester polyol, a compound prepared by reacting various known and low molecular weight polyols with various known and conventional polycarboxylic acids or various reactive derivatives thereof by various known and conventional methods. Can be used.

  Examples of the low molecular weight polyol used in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6. -Hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1, Aliphatic diols such as 3-propanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, alicyclic diols such as hydrogenated bisphenol A, and glycerin, trimethylolpropane, pen as polyfunctional components Polyol of erythritol, and the like. These may be used alone or in combination of two or more.

Examples of the polycarboxylic acid used in the present invention include succinic acid, succinic anhydride, adipic acid, suberic acid, azelaic acid, sebacic acid, and dimer acid. , Aliphatic dicarboxylic acids and alicyclic dicarboxylic acids such as maleic anhydride, fumaric acid and 1,4-cyclohexanedicarboxylic acid, and polycarboxylic acids such as trimellitic acid, pyromellitic acid and cyclohexanetricarboxylic acid as polyfunctional components, and Examples of such anhydrides or ester-forming derivatives, and aromatics include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane p, p'aromatic dicarboxylic acids and anhydrides or ester forming derivatives thereof such as dicarboxylic acids, and aromatic hydroxy carboxylic acids and ester-forming derivatives thereof such as p- hydroxybenzoic acid.
Moreover, you may use cyclic ester, for example, (epsilon) -caprolactone, (gamma) -valerolactone, etc. are mentioned.
Further, as dicarboxylic acid containing an aromatic sulfonic acid group or an ester derivative thereof, for example, dicarboxylic acid such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, 5 [4-sulfophenoxy] isophthalic acid or an ester thereof. Derivative Na, K, Li salts are mentioned.

  Further, since the polyester polyol containing an aromatic sulfonic acid group is an ester of an aromatic acid, it is excellent in hydrolysis resistance and has storage stability and durability that have been a problem as an aqueous polyurethane resin. It is also effective for improvement.

  Moreover, the water resistance and heat resistance of the water-based polyurethane resin (A) can be selected by arbitrarily selecting a low molecular weight polyol and further introducing a lactone monomer having good water resistance into the polyester polyol containing the aromatic sulfonic acid group. It is possible to adjust the cohesive force and the like within a target range.

As the polyether polyol that can be used as the high molecular weight polyol, for example, in the presence of a compound having an active hydrogen atom (reactive hydrogen atom), for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, Alternatively, it is a polymer obtained by ring-opening polymerization of a cyclic ether having three or more members such as epichlorohydrin or a mixture of two or more kinds.
Examples of such polyether polyols include polyethylene glycol, polypropylene glycol, or polytetramethylene glycol.
Further, polyether monool partially blocked with a monoalcohol such as methanol or butanol may be used as long as the high molecular weight is not inhibited.

  Examples of the polycarbonate polyol that can be used as the high molecular weight polyol include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene. A reaction product of a diol such as glycol and a cyclic carbonate represented by, for example, a dialkyl carbonate such as dimethyl carbonate or ethylene carbonate.

Examples of the raw material used for introducing a hydrophilic group into the aqueous polyurethane resin (A) used in the present invention include at least one active hydrogen atom in the molecule, and a carboxylic acid salt or sulfonic acid salt. Basically ionic compound containing at least one functional group selected from the group consisting of salts, phosphoric acid salts, quaternary ammonium salts, carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, and tertiary amino groups Or a nonionic compound having at least one active hydrogen atom in the molecule and containing a group consisting of a repeating unit of ethylene oxide, a group consisting of a repeating unit of ethylene oxide and another repeating unit of alkylene oxide, etc. Can be mentioned.
Examples of the hydrophilic group-containing compound include 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid, 1,3-phenylenediamine-4,6-disulfonic acid. Sulfonic acid-containing compounds such as 2,4-diaminotoluene-5-sulfonic acid and derivatives thereof or polyester polyols obtained by copolymerization thereof; 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2,6-dioxybenzoic acid, carboxylic acid-containing compounds such as 3,4-diaminobenzoic acid, and derivatives thereof, or polyester polyols obtained by copolymerizing these; Methyldiethanolamine, butyldiethanolamine, alkyldi Tertiary amino group-containing compounds such as propanolamine and derivatives thereof, or polyester polyols or polyether polyols obtained by copolymerization thereof; the tertiary amino group-containing compounds and derivatives thereof or obtained by copolymerization thereof. Reaction of polyester polyol or polyether polyol with quaternizing agents such as methyl chloride, methyl bromide, dimethyl sulfate, diethyl sulfate, benzyl chloride, benzyl bromide, ethylene chlorohydrin, ethylene bromohydrin, epichlorohydrin, bromobutane Polyoxyethylene glycol or polyoxyethylene-polyoxypropylene having a molecular weight of 300 to 20,000 containing at least 30% by weight of repeating units of ethylene oxide and containing at least one active hydrogen in the polymer Nonionic group-containing compounds such as polymer glycol, polyoxyethylene-polyoxybutylene copolymer glycol, polyoxyethylene-polyoxyalkylene copolymer glycol or monoalkyl ether thereof, or polyester polyether obtained by copolymerization thereof A polyol is mentioned, These can be used individually or in combination of 2 or more types.

The following are mentioned as a polyamine as a chain extender used when preparing the said water-based polyurethane resin (A).
Examples of typical polyamines having an average number of functional groups of amino groups in one molecule of 2 or more and a molecular weight of 300 or less include 1,2-diaminoethane, 1,2- or 1,3-diaminopropane, 1,2-, 1,3- or 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, piperazine, N, N′-bis- (2-aminoethyl) piperazine, 1- Amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophoronediamine), bis- (4-aminocyclohexyl) methane, bis- (4-amino-3-butylcyclohexyl) methane, 1,2-, Diamines such as 1,3- or 1,4-diaminocyclohexane or 1,3-diaminopropane, diethylenetriamine, triethylenete Polyamines such as lamin, hydrazine derivatives such as hydrazine or adipic acid dihydrazide, sulfonic acid diamines described in Japanese Patent Publication No. 49-36693 and Canadian Patent No. 928,323, or N- (2- Aminoethyl) sodium 2-aminopropionate can also be used.

Further, as the chain extender used when preparing the aqueous polyurethane resin (A), the low molecular weight polyol having 2 or more functional groups and a molecular weight of 300 or less can also be used.
Furthermore, polyamines having a total number of functional groups of amine groups and hydroxyl groups in one molecule of 2 or more and a molecular weight of 300 or less, that is, amino alcohols can also be used. Examples of such compounds include ethanolamine, N-methyl, and the like. Examples include diethanolamine, propanolamine, N-methyldiisopropanolamine, N-ethyldiethyleneamine, N-ethyldiisopropanolamine, aminoethylethanolamine, diethanolamine and the like.
As described above, by using a polyamine having a functional group number of 2 or more and a molecular weight of 300 or less and / or a low molecular weight polyol, the cohesive force of the polyurethane resin (A) is increased, and further, the initial heat resistance is increased by increasing the molecular weight. Improvement is possible.

  The aqueous polyurethane resin (A) can be prepared by a known and commonly used method. For example, in an organic solvent having no active hydrogen-containing group in the molecule, the reaction temperature is not particularly limited, but is preferably 30. It is the range of -150 degreeC, More preferably, it is the range of 50-120 degreeC.

  In the preparation of the aqueous polyurethane resin (A), an equivalent ratio of polyisocyanate and polyol to isocyanate group (hereinafter abbreviated as NCO group) and hydroxyl group (hereinafter abbreviated as OH group) is usually preferably. By reacting in the range of NCO group / OH group = (3-1) / 1 equivalent ratio, more preferably in the range of (2-1) / 1 equivalent ratio, (I) prepolymer reaction [NCO group is OH In the case of excess with respect to the group], or (II) urethanization reaction [in the case of NCO group / OH group = 1/1].

Subsequent to the above reaction, in the case of (I) prepolymerization reaction, for example, the carboxylate group and / or sulfonate group in the molecule is neutralized using, for example, ammonia, organic amine, metal hydroxide or the like. Then, this is thrown into water and emulsified and dispersed, and finally, a polyamine is added to the obtained emulsion containing the remaining NCO groups and the chain is elongated. At this time, the number of functional groups of the polyamine is preferably 2 or more, and the amino group (hereinafter abbreviated as NH group) is usually equivalent to an equivalent ratio with respect to the remaining NCO group of the prepolymer, preferably NCO group / NH group = 1 / ( The chain extension reaction is performed in the range of 0.5 to 1.2) equivalent ratio, more preferably in the range of NCO group / NH group = 1: (0.5 to 1.0) equivalent ratio.
On the other hand, in the case of (II) urethanization reaction, for example, in order to neutralize the carboxylate group and / or sulfonate group in the molecule, ammonia, organic amine, metal hydroxide, etc. are added to the reaction solution. Examples include a method of neutralizing by adding, then adding water little by little, and emulsifying and dispersing.
By removing the organic solvent remaining in the emulsion obtained by the method exemplified in the prepolymerization reaction (I) or the aqueous urethanization reaction (II) by an appropriate method such as distillation under reduced pressure, the desired polyurethane resin (A) can be obtained.

In preparing the aqueous polyurethane resin (A), a surfactant may be used within a range not impairing the effects of the present invention for the purpose of improving emulsification dispersibility and permeability.
As the molecular structure of the surfactant, both the hydrophobic part and the hydrophilic part are present in the same molecule, and both parts have an appropriate balance. Usually, surfactants are classified according to the type of hydrophilic part, and the hydrophilic part is an anionic type in which molecules are anionized in water, as represented by carboxylic acid group, sulfate ester group, and allyl sulfonic acid group. Surfactant, or a cationic surfactant that cationizes a molecule whose hydrophilic part is an amine salt or quaternary ammonium salt, or a hydrophilic part is represented by a hydroxyl group, an ether group, an ester group or the like Thus, there are nonionic surfactants whose whole molecule is nonionic, or amphoteric surfactants having both anionic and cationic polar groups in one molecule.
Examples of the hydrophobic part of the surfactant used in the present invention include a chain hydrocarbon group or a group containing a cyclic hydrocarbon group or a fluorinated alkyl group having 4 to 20 carbon atoms. . Examples of the hydrophilic portion include nonionic polar groups or ionic polar groups such as anions, cations, and betaines.

  In the present invention, the method for adding the surfactant is not particularly limited, and it may be added at any stage during the preparation of the aqueous polyurethane resin (A), or may be added at any stage after completion of the reaction. Absent.

The anionic surfactant used in the preparation of the aqueous polyurethane resin (A) is not particularly limited. For example, fatty acid salts such as potassium oleate soap and castor oil potassium soap, or alkyl such as sodium lauryl sulfate and ammonium lauryl sulfate. Sulfate esters, alkyl naphthalene sulfonates such as sodium alkyl naphthalene sulfonate, alkyl diallyl ether sulfonates such as sodium alkyl diphenyl ether disulfonate, alkyl phosphates such as diethanol amine alkyl phosphate, or aromatic sulfonic acids Sodium salt of formalin condensate, sodium polyoxyethylene alkyl ether sulfate, ammonium sulfate of polyoxyethylene alkyl ether and polyoxyethylene alkyl ether Such as polyoxyethylene alkyl and alkyl allyl ether sulfate Ji alkylphenyl ether sulfate or such fluorine-based active agents perfluoroalkyl carboxylate, or a carboxylic acid type polymeric active agents.
Further, the cationic surfactant used in the preparation of the aqueous polyurethane resin (A) is not particularly limited. For example, an alkylamine salt such as stearylamine acetate or a quaternary ammonium salt such as stearyltrimethylammonium chloride. Is mentioned.
In addition, the nonionic surfactant used in the preparation of the aqueous polyurethane resin (A) is not particularly limited. For example, polyoxyethylene alkyl ether such as polyoxyethylene lauryl ether, or polyoxyethylene octylphenyl ether, Polyoxyethylene alkyl phenyl ether such as polyoxyethylene nonylphenyl ether, or ethylene oxide adduct of acetylene diol, polyoxyethylene derivative, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid monoglyceride, polyethylene glycol fatty acid ester, polyoxy And polyoxyethylene alkylamines such as ethylene laurylamine.
In addition, the amphoteric surfactant used in the preparation of the aqueous polyurethane resin (A) is not particularly limited, and examples thereof include alkylbetaines such as laurylbetaine and amine oxides such as lauryldimethylamine oxide.

As the aqueous polyurethane resin (A), which is an essential component of the aqueous resin coating agent of the present invention, an anionic self-emulsifying aqueous urethane resin is preferably used.
As the hydrophilic group for imparting water dispersibility (hydrophilicity) to the aqueous polyurethane resin (A), for example, anionic groups such as a carboxylate group and a sulfonate group are preferable because of their excellent solubility in water.
As an aqueous polyurethane resin (A) that is an essential component of the aqueous resin coating agent of the present invention, by using an anionic self-emulsifying aqueous urethane resin, a fire brick made by applying this aqueous resin coating agent is used. The adhesive strength does not decrease due to the bleeding out of the surfactant to the adhesive interface between the coating agent and the brick as in the case of an aqueous urethane resin using a surfactant as an emulsifier.

  In the aqueous resin coating agent of the present invention, the aqueous polyurethane resin (A) is contained in the range of 5 to 40% by mass, preferably in the range of 7 to 25% by mass, based on the total solid content in the aqueous resin coating agent. To do. If the aqueous polyurethane resin (A) is contained in such a range, an aqueous resin coating agent having excellent adhesion and abrasion resistance can be obtained.

Next, the acrylic resin emulsion (B), which is the second component of the aqueous resin coating agent of the present invention, will be described below.
The acrylic resin emulsion (B) is at least one polymerizable monomer selected from (meth) acrylic acid ester and (meth) acrylic acid in the presence of a polymerization initiator, an emulsifier and / or a dispersion stabilizer. The polymer can be used as a main polymerization component, and other polymerizable monomers copolymerizable with the polymerizable monomer can be copolymerized within a range not impairing the object of the present invention.
In the present invention, “(meth) acrylic acid” and “(meth) acrylic acid ester” are “acrylic acid and / or methacrylic acid” and “acrylic acid ester and / or methacrylic acid”, respectively, unless otherwise specified. Means "acid ester".

  As a polymerization method for obtaining the acrylic resin emulsion (B), for example, (i) a method in which water, a polymerizable monomer, an emulsifier, a polymerization initiator and the like are mixed at once, or (ii) water, Examples include a so-called pre-emulsion method in which a polymerizable monomer and an emulsifier previously mixed are dropped, or (iii) a monomer dropping method.

  Examples of (meth) acrylic acid and (meth) acrylic acid ester used for the preparation of the acrylic resin emulsion (B) include (meth) acrylic acid, β-carboxyethyl (meth) acrylate, and 2- (meth) acryloylpropionic acid. , Crotonic acid, itaconic acid, maleic acid, fumaric acid, itaconic acid half ester, maleic acid half ester, maleic anhydride, itaconic anhydride, β- (meth) acryloyloxyethyl hydrogen succinate, β- (meth) hydroxyethyl Hydrogen phthalate and salts thereof, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hex (Meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (Meth) acrylates such as phenyl (meth) acrylate and benzyl (meth) acrylate; 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate , Fluorine-containing ethylenically unsaturated monomer glycidyl such as perfluorocyclohexyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, β- (perfluorooctyl) ethyl (meth) acrylate ( Glycidyl group-containing polymerizable monomers such as meth) acrylate and allyl glycidyl ether; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate Hydroxyl group-containing polymerizable monomers such as aminoethyl (meth) acrylate, N-monoalkylaminoalkyl (meth) acrylate, amino group-containing polymerizable monomers such as N, N-dialkylaminoalkyl (meth) acrylate; 2-aziridinylethyl (meth) acrylate and other aziridinyl group-containing polymerizable monomers; allyl (meth) acrylate and other allyl group-containing polymerizable monomers; dicyclopentenyl (meth) acrylate and other cyclopentenyl group-containing monomers Polymerizable monomer; ethylene Cold di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) Examples include acrylate, diallyl phthalate, divinyl benzene, and allyl (meth) acrylate. These may be used alone or in combination of two or more.

  Furthermore, other polymerizable monomers that can be copolymerized include, for example, N-methylol (meth) acrylamide, N-isopropoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, and N-isobutoxy. Methylolamide group such as methyl (meth) acrylamide or its alkoxylated polymer-containing polymerizable monomer; vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ- (meth) acrylic Roxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryloxy Propyltriiso Siloxy group-containing polymerizable monomers such as ropoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride; (meth) acryloyl isocyanate, (meth) acryloyl isocyanate Isocyanate group and / or blocked isocyanate group-containing polymerizable monomer such as ethyl phenol or methyl ethyl ketoxime adduct; Oxazoline group-containing polymerizable monomer such as 2-isopropenyl-2-oxazoline and 2-vinyl-2-oxazoline Polymers; Amide group-containing polymerizable monomers such as (meth) acrylamide, N-monoalkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide; Polymers containing carbonyl groups such as acrolein and diacetone (meth) acrylamide Monomer; acetoacetate An acetoacetyl group-containing polymerizable monomer such as siethyl (meth) acrylate, a sulfonic acid group and / or a sulfate group (and / or a salt thereof), a phosphoric acid group and / or a phosphate ester group (and / or a salt thereof) Containing ethylenically unsaturated monomers, vinyl sulfonic acids such as vinyl sulfonic acid and styrene sulfonic acid or salts thereof, allyl group-containing sulfonic acids such as allyl sulfonic acid and 2-methylallyl sulfonic acid or salts thereof, ) (Meth) acryloyl group-containing sulfonic acids such as 2-sulfoethyl acrylate and 2-sulfopropyl (meth) acrylate or salts thereof, and (meth) acrylamide group-containing sulfonic acids such as (meth) acrylamide-t-butylsulfonic acid Or a salt thereof, “Adekalia Soap PP-70” having a phosphate group, “Adekalia Soap PPE” 710 "(manufactured by Asahi Denka Kogyo Co., Ltd.); vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl ether, hexyl vinyl ether, etc. Vinyl ethers of nitrile groups; ethylenically unsaturated monomers containing nitrile groups such as (meth) acrylonitrile; aromatic rings such as styrene, α-methylstyrene, vinyltoluene, vinylanisole, α-halostyrene, vinylnaphthalene, divinylstyrene Vinyl compounds; and monomers capable of radical polymerization such as isoprene, chloroprene, butadiene, ethylene, tetrafluoroethylene, vinylidene fluoride, and N-vinylpyrrolidone. These 1 type, or 2 or more types of mixtures can be used.

  As the emulsifier used in the preparation of the acrylic resin emulsion (B), the above-mentioned emulsifiers can be used.

Furthermore, when preparing the acrylic resin emulsion (B), an emulsifier having a polymerizable unsaturated group in the molecule, generally referred to as “reactive emulsifier”, can also be used.
As such a reactive emulsifier, for example, “Latemul S-180” (manufactured by Kao Corporation), “Eleminol JS-2”, “Eleminol RS-30” (Sanyo Kasei) having a sulfonic acid group and a salt thereof are commercially available products. "AQUALON HS-10", "AQUALON HS-20" (Daiichi Kogyo Seiyaku Co., Ltd.), "ADEKA rear soap SE-10", "ADEKA" having sulfate groups and salts thereof “Rear Soap SE-20” (manufactured by Asahi Denka Kogyo Co., Ltd.) and the like; “New Frontier A-229E” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) having a phosphate group, etc .; “Aquaron having a nonionic hydrophilic group” RN-10, Aqualon RN-20, Aqualon RN-30, Aqualon RN-50 (Daiichi Kogyo Seiyaku Co., Ltd.), etc. Both It may be.

  Further, other dispersion stabilizers other than the emulsifier that can be used for the preparation of the acrylic resin emulsion (B) include, for example, polyvinyl alcohol, fiber ether, starch, maleated polybutadiene, maleated alkyd resin, and polyacrylic acid. (Salts), polyacrylamide, water-based acrylic resins, water-based polyester resins, water-based polyamide resins, water-based polyurethane resins, and other synthetic or natural water-soluble polymer materials may be mentioned. These may be used alone or in combination of two or more. May be.

The aqueous medium used for preparing the acrylic resin emulsion (B) is not particularly limited as long as it does not inhibit the reaction, and only water may be used, or a mixture of water and a water-soluble solvent may be used. A solvent may be used.
Examples of the water-soluble solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl carbitol, ethyl cellosolve, and butyl cellosolve, and polar solvents such as N-methylpyrrolidone. More than one species may be used in combination.

  As the polymerization initiator used when preparing the acrylic resin emulsion (B), it is preferable to use a radical polymerization initiator. Examples of the radical polymerization initiator include potassium persulfate, sodium persulfate, and ammonium persulfate. Persulphates, diacyl peroxides such as benzoyl peroxide, lauroyl peroxide, decanoyl peroxide, t-butyl cumyl peroxide, dialkyl peroxides such as dicumyl peroxide, t-butyl peroxylaurate, Peroxyesters such as t-butylperoxybenzoate, organic peroxides such as cumene hydroperoxide, paramentane hydroperoxide, hydroperoxides such as t-butyl hydroperoxide, hydrogen peroxide, etc. Et That.

Moreover, the redox polymerization initiator which used together the said peroxides and a reducing agent can also be used.
Examples of such a reducing agent include ascorbic acid and salts thereof, erythorbic acid and salts thereof, tartaric acid and salts thereof, citric acid and salts thereof, metal salts of formaldehyde sulfoxylate, sodium thiosulfate, sodium bisulfite, secondary chloride. Iron etc. are mentioned. It is also possible to use azo initiators such as 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride. These polymerization initiators may be used alone or in combination of two or more.

Moreover, the compound which has chain transfer ability can be used as a molecular weight modifier in order to adjust the molecular weight of the polymer which comprises the said acrylic resin emulsion (B).
Examples of such molecular weight regulators include mercaptans such as lauryl mercaptan, octyl mercaptan, dodecyl mercaptan, 2-mercaptoethanol, octyl thioglycolate, 3-mercaptopropionic acid, thioglycerin, α-methylstyrene dimer, and the like. It is done.

Moreover, a neutralizing agent can be used in order to neutralize the carboxyl group of the acrylic resin emulsion (B).
As the neutralizing agent, a basic substance can be used, for example, alkali metal compounds such as sodium hydroxide and potassium hydroxide; alkaline earth metal compounds such as calcium hydroxide and calcium carbonate; ammonia; monomethylamine; Examples include water-soluble organic amines such as dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dimethylpropylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, and diethylenetriamine. You may use 2 or more types together. Among these neutralizing agents, it is preferable to use ammonia that is easily scattered by normal temperature or heating, particularly when the purpose is to further improve the water resistance of the coating.

  The polymerization temperature for preparing the acrylic resin emulsion (B) varies depending on the type of monomer used, the type of polymerization initiator, etc., but is usually in the range of 30 to 90 ° C. when polymerizing in an aqueous medium. Preferably it is done.

  The average particle diameter (50% median diameter) of the acrylic resin emulsion (B) is preferably in the range of 250 to 1500 nm. If the average particle diameter of the acrylic resin emulsion (B) is within such a range, the drying property of the coating film at the time of film formation is excellent.

  In the aqueous resin coating agent of the present invention, the acrylic resin emulsion (B) is contained in the range of 5 to 40% by mass, preferably in the range of 5 to 25% by mass. If the acrylic resin emulsion (B) is contained in such a range, an aqueous resin coating agent excellent in drying property and leveling property when applied can be obtained.

Next, a typical configuration of the latex (C), which is the third component of the aqueous resin coating agent of the present invention, will be described below, but is not limited thereto.
The latex (C) is an aliphatic conjugated diene monomer (a), a (meth) acrylic acid alkyl ester monomer (b) having an alkyl group having 1 to 10 carbon atoms, Typical examples are those obtained by emulsion polymerization of a carboxyl group-containing vinyl monomer (c) and, if necessary, another vinyl monomer (d) copolymerizable.

  Examples of the aliphatic conjugated diene monomer (a) used for the preparation of the latex (C) include 1,3-butadiene, isoprene, chloroprene and the like, and these aliphatic conjugated diene monomers ( a) may be used alone or in combination of two or more.

  Moreover, as a (meth) acrylic-acid alkylester type | system | group monomer (b) used for adjustment of the said latex (C) whose carbon atom number of an alkyl group is 1-10, for example, (meth) acrylic acid methyl , Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, octadecyl (meth) acrylate, etc. If the number of carbon atoms of the alkyl group of the (meth) acrylic acid alkyl ester monomer (b) is in the range of 1 to 10, the resulting aqueous resin coating agent has adhesiveness and drying properties. Excellent balance. These (meth) acrylic acid alkyl ester monomers may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing vinyl monomer (c) used for the preparation of the latex (C) include (meth) acrylic acid, crotonic acid, maleic acid and its anhydride, fumaric acid, itaconic acid, Unsaturated dicarboxylic acid monoalkyl esters (for example, monomethyl maleate, monoethyl fumarate, mononormal butyl itaconate, etc.) and the like. These carboxyl group-containing vinyl monomers (c) may be used alone or in combination of two types. You may use the above together.

  Furthermore, examples of other copolymerizable vinyl monomers (d) that may be used for adjusting the latex (C) include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, 2,4. -Ethylenically unsaturated aromatic monomers such as dibromostyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate; vinylidene halides such as vinylidene chloride and vinylidene bromide; ) Hydroxyalkyl esters of ethylenically unsaturated carboxylic acids such as -2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate; glycidyl esters of ethylenically unsaturated carboxylic acids such as glycidyl (meth) acrylate; (Meth) acrylamide, N-methylol (meth) acrylami , Butoxymethyl (meth) acrylamide, diacetone acrylamide, etc. These other copolymerizable vinyl monomer (d), may be used in combination well 2 or more types may be used alone.

  As a method for adjusting the latex (C), for example, the monomers (a) to (c), or the monomers (a) to (c), in an aqueous medium in the presence of an emulsifier, a polymerization initiator, and the like. It can be obtained by emulsion polymerization using (d), and in this case, a two-stage polymerization method can also be adopted.

  As the surfactant used as an emulsifier for the preparation of the latex (C), those represented by the aforementioned surfactants can be used.

Examples of the polymerization initiator used when preparing the latex (C) include aqueous catalysts such as potassium persulfate (K ₂ S ₂ O ₈ ), ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), and hydrogen peroxide. Or oily catalysts such as t-butyl hydroperoxide and cumene hydroperoxide.

  In the polymerization reaction, other additives can usually be used. Examples of such other additives include a chain transfer agent, ethylenediaminetetraacetic acid, a pH adjuster (for example, an alkaline substance), and the like.

  Furthermore, the latex (C) is preferably used after being concentrated to the required solid content by a method such as stripping, for the purpose of reducing odor due to unreacted monomers.

  In the aqueous resin coating agent of the present invention, the latex (C) is contained in the range of 5 to 40% by mass, preferably in the range of 8 to 25% by mass. This latex is used for blending the inorganic filler (D) at a high concentration. In other words, since the inorganic filler has a high specific gravity in the aqueous solution, the inorganic filler is likely to settle. Therefore, the latex can be prevented from settling, and an aqueous resin coating agent having a uniform concentration can be obtained. If the latex is 5% by mass or less, an aqueous resin coating agent having a uniform concentration capable of suppressing sedimentation of the inorganic filler tends to be not obtained, and if it exceeds 40% by mass, the strength of the coating film tends to decrease.

Next, the inorganic filler (D), which is the fourth component of the aqueous resin coating agent of the present invention, will be described below.
Examples of the inorganic filler (D) include metal powders such as aluminum and iron, siliceous substances such as silica and diatomaceous earth, clays such as silicate and alumina, and calcareous substances such as calcium carbonate, magnesium carbonate, and gypsum. Or siliceous siliceous materials such as mica and clay, or maternal silicic materials such as talc and asbestos, or carbon, carbides such as graphite and carbon black, and other inorganic materials such as antimony oxide, and these inorganic fillers. May be used alone or in combination of two or more. Among these, calcium carbonate and / or magnesium carbonate is preferable, and calcium carbonate is more preferable.
The aqueous resin coating agent of the present invention can be improved in blocking resistance and drying property by using the inorganic filler (D). Since this blocking resistance improves, peeling from the surface of the brick at the time of line conveyance can be improved significantly.
As the inorganic filler (D), calcium carbonate and / or magnesium carbonate, which are more excellent in terms of dispersibility in the resin and compatibility, are preferable. Furthermore, when these are applied to bricks, they receive heat during use and generate carbon dioxide gas up to 1000 ° C., reducing the volume of the coating film and causing the expansion of the bricks. On the other hand, on the back side of the brick, since the temperature does not rise until foaming during use, the brick is firmly held to prevent the brick from falling off. This is because a considerably large temperature gradient is generated because the entire length of the brick is long. In particular, in the case of magnesia carbon brick, when the temperature is 1000 ° C. or higher, the coating film exists as magnesia or calcia, so that there is an effect of ensuring the corrosion resistance as a joint. Furthermore, in the case of calcium carbonate, calcia generated at high temperature is excellent in adhesion to slag, so that the joint is protected and the wear resistance of the joint is more effectively suppressed, so that the corrosion resistance of the brick is improved. For this reason, it is more preferable to use calcium carbonate.

  In the aqueous resin coating agent of the present invention, the inorganic filler (D) is in the range of 40 to 85% by mass, preferably in the range of 50 to 85% by mass, based on the total solid content in the aqueous resin coating agent. More preferably, it contains in the range of 55-80 mass%. If the content ratio of the inorganic filler (D) with respect to the solid mass in the aqueous resin coating agent is within such a range, it is possible to achieve both blocking resistance and dispersibility and a uniform coating agent film thickness. Excellent coating effect can be obtained.

  In addition, ordinary auxiliary materials and additives, for example, plasticizers, tackifiers (rosin resin, rosin ester resin, terpene resin, terpene phenol resin petroleum resin, Coumarone resin, etc.), fillers, pigments, pH adjusters, film forming aids, leveling agents, water repellents, antifoaming agents, thickeners, antioxidants, ultraviolet absorbers, flame retardants, etc. it can.

  Further, a water-soluble or water-dispersible thermosetting resin can be mixed with the aqueous resin coating agent of the present invention, and examples of such thermosetting resins include phenol resins, urea resins, melamine resins, polyesters. Examples thereof include resins and polyamide resins.

The water-based polyurethane resin (A) contained in the water-based resin coating agent of the present invention can be used alone, but a cross-linking agent that can be used in a publicly known aqueous dispersion can also be used. Examples include bifunctional or higher functional compounds such as melamine resin, urea resin, epoxy compound, aziridine compound, carbodiimide compound, oxazoline compound, polyisocyanate compound, and among these, polyisocyanate compound Is preferred.
Examples of the crosslinking agent include polyisocyanates composed of trimers such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4′-diisocyanate diphenylmethane (MDI), xylylene diisocyanate, and isophorone diisocyanate. Or a plurality of isocyanate groups formed by reacting the polyisocyanate with low molecular weight active hydrogen compounds such as ethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, polyoxyethylene glycol, and long-chain higher alcohol. Examples thereof include a compound having a terminal in the molecule and a blocked polyisocyanate blocked with an isocyanate group, ε-caprolactam, phenol or the like.
As the usage-amount of the said crosslinking agent, the range of 0.1-50 mass% is preferable with respect to solid content mass of a polyurethane resin (A).

  Examples of the mixing method of the aqueous resin coating agent of the present invention include methods such as mechanical stirring and mixing using a homomixer, and mixing using a static mixer, and the mixing that provides an aqueous resin coating agent having the intended performance of the present invention. If it is a method, it will not specifically limit.

As described above, the aqueous resin coating agent of the present invention is an aqueous resin coating agent containing an aqueous polyurethane resin (A), an acrylic resin emulsion (B), a latex (C), and an inorganic filler (D) as essential components. The aqueous polyurethane resin (A) is 5 to 40% by mass, the acrylic resin emulsion (B) is 5 to 40% by mass, and the latex (C) with respect to the total solid mass in the aqueous resin coating agent. 5) to 40% by mass and the inorganic filler (D) in the range of 40 to 85% by mass, and improving the adhesion between the aqueous resin coating layer and the brick surface. , It can greatly improve the separation of bricks from the surface during transport and handling of refractory bricks during construction, can build refractory bricks without any separation, and the expansion absorption of bricks in use Between bricks Excellent in the effect of a uniform joint thickness.
In other words, by combining a water-soluble resin coating agent and an inorganic filler, it is possible to make the inorganic filler of the coating film after removing moisture high, so the hardness of the coating film is very hard and high in strength Therefore, for example, even when a part of the coating film on the brick surface is caught on a part of the brick conveying device during brick conveyance, it is unlikely to become a starting point, which is extremely effective in preventing production process troubles and defective products.

[Fire bricks]
Next, the firebrick of the present invention will be described below.
The refractory brick of the present invention is obtained by applying the aqueous resin coating agent of the present invention on a graphite-containing brick.
Since this refractory brick is used for the inner wall of a furnace body such as a converter or a pan, it is necessary to withstand severe use conditions under a high temperature of, for example, about 1650 ° C. during the preheating of the furnace or at the initial stage of operation. For this reason, it is essential to prevent “cracking” caused by the thermal expansion of bricks and to prevent the paint on the brick surface from peeling off even under the severe brick handling conditions in the construction work. Very important.
Further, among the graphite-containing bricks, the magnesia carbon brick easily contains cracks because it contains magnesia. For this reason, the effect excellent in prevention of a crack can be acquired by apply | coating the aqueous resin coating agent of this invention to the surface of a magnesia carbon brick.
The graphite-containing brick referred to in the present invention is an unfired brick using scale carbon or the like such as alumina carbon brick or magnesia carbon brick.
The magnesia carbon brick is a magnesia carbon brick generally used in converters, electric furnaces, ladles, refining furnaces, etc., and generally contains magnesia clinker, scaly graphite and organic resin. It is obtained by heat treatment after molding. However, in some cases, a part of the magnesia clinker is replaced with calcia clinker, dolomite clinker, spinel clinker, or the like, or a carbon raw material other than metal powder, antioxidant, and scaly graphite may be used.

It is preferable to apply the aqueous resin coating agent so that the thickness after drying is in the range of 0.1 to 0.4 mm. If the coating amount is within such a range, the joint thickness between the bricks can be made uniform, and it is possible to prevent cracking.
Moreover, this application | coating may be performed with a brush on a MgO-C brick, and a metal or rubber | gum roll may be sufficient and it does not specifically limit.
After apply | coating the said water-based resin coating agent on MgO-C brick, it is left to dry normally at room temperature for 10 to 24 hours, or is dried at 100-120 degreeC, and the refractory brick of this invention is manufactured.
A pencil scratch test, a cross cut test, a coin scratch test, and the like are performed on the refractory brick obtained by applying the aqueous resin coating agent of the present invention thus obtained.

  The refractory brick of the present invention uses an anionic self-emulsifying water-based polyurethane resin as the water-based polyurethane resin (A), which is an essential component of the water-based resin coating agent. The adhesive strength does not decrease due to bleeding out of the emulsifier to the adhesive interface with the brick.

  In addition, the firebrick of the present invention has excellent anti-slip and anti-slip properties, and particularly excellent adhesion to the brick surface, so that it can greatly improve peeling from the brick surface during line transportation. For example, it is extremely useful for bricks used under severe conditions at high temperatures such as the inner walls of furnace bodies such as converters and ladles.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited only to these Examples. In the text, “part” and “%” are based on mass unless otherwise specified.
Various physical properties were tested and judged by the methods described below.

[Pencil scratch test method]
In accordance with the pencil scratch value and the hand scratch method of the general test method for paints described in Japanese Industrial Standard JIS K-6400, the coating film was evaluated for scratches, and the result was shown as pencil hardness. The pencil hardness indicates that the hardness increases in the order of F, H, 2H, 3H, 4H, 5H, and 6H, F is the softest, and 6H is the hardest.

[Cross cut test method]
In accordance with the cross-cut tape method of the general test method for paints described in Japanese Industrial Standards JIS K-6400, after attaching a predetermined cellophane adhesive tape, it is peeled off and the area of the tightly adhered part is The percentage of the total area is expressed in%.

[Coin scratch test method]
The coated surface was strongly scratched 10 times at the coin edge, and the state of peeling of the coating film was observed and evaluated according to the following criteria.
○: No damage or peeling of the coating film.
Δ: A state in which a part of the coating film is peeled off.
X: The state in which the coating film is completely peeled off.

[Evaluation criteria for dispersion stability of paint mixture]
The evaluation criteria for the dispersion stability of the coating solution blends described in Tables 1 and 2 are as follows.
A: No inorganic filler settled after standing at room temperature for 2 weeks.
○: The inorganic filler is hardly precipitated after standing at room temperature for 2 weeks.
Δ: A small amount of inorganic filler settled after standing at room temperature for 2 weeks.
X: A large amount of inorganic filler settled after standing at room temperature for 2 weeks.
-: Not measured because no inorganic filler was added.

[Measurement method of residual area ratio of water-based resin coating agent on brick surface]
An MgO—C brick having a carbon content of 20% generally used as a converter brick having an upper surface of 130 mm × 130 mm, a bottom surface of 150 mm × 150 mm, a height of 810 mm, and a mass of 50 kg was used. In FIG. 1, the schematic of the MgO-C brick used for the measurement experiment of the remaining area ratio of a water-based resin coating agent is shown. First, a water-based resin coating agent is applied to the bonding surfaces of two MgO-C bricks, completely cured, then overlapped, and the upper brick is slid on the lower brick in the length direction of 810 mm. After repeating the movement, the area where the applied coating agent was peeled off (the area of the peeled portion) was measured, and the residual area ratio (%) of the coating agent was obtained from the following equation.
Residual area ratio of coating agent (%) = [initial area−area of peeled portion] / initial area × 100
FIG. 2 is a schematic view showing a method for measuring the remaining area ratio of the water-based resin coating agent in which two MgO-C bricks are overlapped and the upper brick is slid on the lower brick. The sliding distance is 810 mm from the position where the end face of the upper brick comes to the center part of the lower brick to the other end face of the upper brick comes to the center part of the lower brick. Was repeated 10 times as an evaluation condition.

[Example 1]
Self-emulsifying water-based polyurethane resin (A) [Dainippon Ink Chemical Co., Ltd., Hydran HW-311; solid content 45% by mass, viscosity 150 mPa · s (measurement temperature 23 ° C.), pH 7.8] 30 parts, acrylic resin emulsion (B) [Dainippon Ink Chemical Co., Ltd., Boncoat NST-100; solid content 68% by mass, viscosity 300 mPa · s (measurement temperature 23 ° C.), pH 7.5] 20 parts, Latex (C) [Dainippon Ink Chemical Co., Ltd., Luck Star 7310K; Carboxy-modified styrene-butadiene copolymer, solid content 50% by mass, viscosity 180 mPa · s (measurement temperature 23 ° C.) , PH 8.4] was charged into a mixing container.
Next, after sufficiently stirring until a uniform state is obtained with a propeller-type stirrer, 140 parts of calcium carbonate [manufactured by Nitto Flourishing Co., Ltd., NT-100; average particle size of 2 to 3 μm] is used as the inorganic filler (D). And 1 part of black pigment was added and stirred at 200 rpm for 5 minutes.
Furthermore, 2 parts of an epoxy-based cross-linking agent [Dainippon Ink & Chemicals, CR-5L; solid content: 100% by mass] was added and stirred uniformly, and the aqueous resin coating agent (P-1) of the present invention was added. ) Was prepared. Table 1 shows the blending composition, solid content, and solid content.

The aqueous resin coating agent (P-1) of the present invention obtained as described above was applied to the surface of unfired magnesia carbon brick (unfired MgO-C brick) with a brush so that the application amount was 100 g / m ^2. did. Then, after standing at room temperature (20 to 25 ° C.) for 20 hours, heat treatment was performed at 100 to 105 ° C. for 30 minutes in a hot air circulating dryer.
About this heat-resistant brick (X-1) which apply | coated the aqueous resin coating agent (P-1) of this invention, the said pencil scratch test, the cross cut test, and the coin scratch test were implemented.
The aqueous resin coating agent (P-1) of the present invention was applied to an appropriate thickness, the surface of the coating agent was cured without any problem, and was excellent in adhesion to the refractory brick. The evaluation results are shown in Table 1.

[Example 2]
The aqueous resin coating agent (P-2) of the present invention was prepared in the same manner as in Example 1 except that the blending ratio of the aqueous polyurethane resin (A), acrylic resin emulsion (B), and latex (C) was changed.
The aqueous resin coating agent (P-2) of the present invention obtained as described above was treated and evaluated in the same manner as in Example 1.
The water-based resin coating agent (P-2) of the present invention was excellent in adhesion to refractory bricks, and was excellent in adhesion at the time of conveyance in a line.
Table 1 shows the blending composition, solid content, solid content, and evaluation results of the aqueous resin coating agent (P-2) of the present invention and the refractory brick (X-2) of the present invention formed by applying the same. .

[Comparative Examples 1-8]
The same as Example 1 except that calcium carbonate as the aqueous polyurethane resin (A), acrylic resin emulsion (B), latex (C), and inorganic additive (D) was changed to the blending amounts shown in Tables 1 to 3. Then, water-based resin coating agents (P-3) to (P-10) are prepared and applied to bricks, respectively, and fireproof bricks (X-3) to (X-10) are prepared, and tests such as adhesion are performed. Carried out. These compounding composition, solid content, solid content, and evaluation results are shown in Tables 1-4.

  From the results of Tables 1 to 4, the water-based resin coating agents and fire bricks of Examples 1 and 2 were compared with Comparative Examples 1 to 8, and the pencil scratch test, the cross-cut test, the coin scratch test, and the dispersion of the coating solution mixture It was found that the stability and the remaining area ratio of the aqueous resin coating agent on the brick surface were all excellent.

  The water-based resin coating agent of the present invention can be easily applied with a uniform thickness, has excellent anti-slip properties, anti-slip properties, and adhesion to the brick surface, and performs harsh handling such as brick transportation. However, there is almost no peeling of the coating agent and it has high adhesion. For example, the heat-resistant brick of the present invention can greatly improve the peeling from the surface of the brick during line transportation in the production process, and is extremely useful in quality control.

It is the schematic of the MgO-C brick used for the measurement experiment of the residual area rate of a water-based resin coating agent. It is the schematic which shows the method of the measurement experiment of the residual area ratio of the water-based resin coating agent which piles up two MgO-C bricks and slides the upper brick on the lower brick.

Claims (5)

An aqueous resin coating agent comprising an aqueous polyurethane resin (A), an acrylic resin emulsion (B), a latex (C), and an inorganic filler (D) as essential components,
5-40% by mass of the aqueous polyurethane resin (A), 5-40% by mass of the acrylic resin emulsion (B), and 5% of the latex (C) with respect to the total solid mass in the aqueous resin coating agent. The water-based resin coating agent characterized by containing -40 mass% and the said inorganic filler (D) in 40-85 mass%.   The aqueous resin coating agent according to claim 1, wherein the inorganic filler (D) is calcium carbonate.   The aqueous resin coating agent according to claim 1 or 2, wherein the polyurethane resin (A) is an anionic self-emulsifying aqueous urethane resin.   A firebrick made by applying the aqueous resin coating agent according to any one of claims 1 to 3 onto a graphite-containing brick. A firebrick made by applying the water-based resin coating agent according to any one of claims 1 to 3 on a magnesia carbon brick.

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