JP5968703B2 - Binder coated refractory, mold and method for producing the same - Google Patents

Description

  The present invention relates to a binder-coated refractory coated with a phenol resin binder, a mold formed using the binder-coated refractory, and a method for producing the mold.

  Conventionally, there are various types of mold manufacturing methods, and one of them is a shell mold method. The shell mold method is obtained by molding a refractory aggregate for molds such as cinnabar with a binder and has excellent characteristics such as obtaining a mold with good dimensional accuracy. Has been used a lot.

  As the binder for the shell mold, a thermosetting resin such as a phenol resin is generally used. A fire-resistant aggregate and a thermosetting resin are mixed to form a thermosetting resin on the surface of the fire-resistant aggregate. Prepare coated binder refractory (generally called resin-coated sand), fill this binder-coated refractory into a heated mold, and melt and cure the thermosetting resin binder. Therefore, the mold is made.

  The binder-coated refractory is a solid granule because the thermosetting resin binder on the outer periphery is solid, and its fluidity is good, so the moldability is good. Air transportation is also possible and handling is good. For this reason, the shell mold method using a binder-coated refractory is often used for automobile castings.

  In a binder coated refractory, a phenol resin is generally used as the thermosetting resin binder for coating the surface of the refractory aggregate. There are resin and novolac type phenol resin, and both can be used as a binder. Here, in the above-described casting mold for automobile casting, it is an urgent need to shorten the molding time of the casting mold even by 1 second in order to improve productivity. For this reason, as a binder of a binder coated refractory used for automobile casting, a novolac type phenol using a hexamethylenetetramine as a curing agent, which is faster than a resol type phenol resin among phenol resins. Resin is frequently used (see, for example, Patent Document 1).

JP 2002-265750 A

  However, as described above, even when a novolac type phenol resin is used as a binder phenol resin covering the surface of the refractory aggregate, the effect of shortening the molding time of the mold is not sufficient. .

  As described above, in the shell mold method, for example, a binder-coated refractory is blown and filled into a mold heated to a high temperature of about 300 ° C., and the binder-coated refractory in the mold is injected from the mold surface. By heating the phenol resin binder with the heat transferred to the object, the phenol resin is melted and cured, and the refractory is bonded with the cured phenol resin to mold the mold.

  Here, the binder-coated refractory 2 in the mold is packed together as shown in FIG. 3A, and the heat of the mold is close to the mold surface of the mold. It will be conducted to the binder coated refractory 2 far from the object 2. However, voids S exist between the particles of the binder-coated refractory 2 as shown in FIG. 3A, and the heat transfer between the binder-coated refractory 2 is very slow due to the voids S.

FIG. 3B shows the temperature distribution of the binder-coated refractory in the mold, and schematically shows the relationship between the distance from the mold surface of the mold and the temperature of the binder-coated refractory (RCS). It is shown as an example. And Figure 3 a line L ₁ of (b), in the shell mold process, when the predetermined time elapses after filling the binder coated refractory into the mold, the distance from the mold surface of the mold (horizontal axis ) And the temperature (vertical axis) of the binder-coated refractory. As seen in the line L _1, although the temperature of the binder coated refractory near the mold surface of the mold is higher, the temperature of the binder coated refractory toward the inside away from the mold surface of the mold It is a two-dimensional temperature curve that drops sharply. When the predetermined time (t ₁ ) further elapses, the temperature of the binder-coated refractory away from the mold surface of the mold gradually increases, and the binder-coated refractory in the mold has a line L ₂ as shown in FIG. It becomes temperature distribution.

  In the binder-coated refractory, the binder layer of the phenol resin coated on the surface of the refractory aggregate is solid at room temperature. With some exceptions, phenolic resins are polymerized by addition condensation, and it is said that no solid phase reaction occurs. That is, the binder coated refractory is heated to a temperature at which the phenol resin in the binder layer softens and melts, and the phenol resin in the binder layer is added and condensed only when the binder layer is fused. The reaction is initiated and cured, and a mold can be formed.

Thus, in the state of the line L ₁ of the temperature distribution, for example, FIG. 3 of the binder coated refractory in the mold (b), the binder layer of the electrode closer binder coated refractory to the mold surface of the mold In the case of a binder coated refractory that only reaches the adhesive point and is separated from the mold surface, the addition condensation reaction does not start with the phenol resin of the binder layer. When the predetermined time (t ₁ ) has elapsed and the temperature distribution of the binder-coated refractory in the mold reaches the state of line L _{2 in} FIG. 3B, the binder separated from the mold surface of the mold. The binder layer of the coated refractory also reaches the adhesion point, and the addition condensation reaction starts on the phenol resin of the binder layer also in the binder coated refractory at the center of the mold.

  In this way, after the binder-coated refractory is blown and filled into the mold heated to a high temperature, the heat is transmitted to the binder-coated refractory away from the mold surface of the mold, and this binder is used. Since it takes time for the coated refractory phenolic resin to start the addition condensation reaction, even if a phenolic resin with a high curing rate is used, the effect of shortening the mold molding cycle is not sufficient. It is.

  The present invention has been made in view of the above points, and an object of the present invention is to make it possible to shorten a cycle for forming a mold.

In the binder-coated refractory according to the present invention, the surface of the refractory aggregate is coated with a solid binder layer containing a solid phenol resin and a liquid phenol resin, and the solid binder layer is melted. Chakuten is 80 ° C. or higher, and is characterized in der Rukoto 110 ° C. or less.

  In the present invention, the binder layer on the surface is formed of a solid phenol resin and a liquid phenol resin, but since it is solid, the binder coated refractory is a smooth granular material and has good fluidity. , Good filling properties to the mold can be obtained. Since the binder layer is formed of a solid phenol resin and a liquid phenol resin in this way, it can be adjusted so that the fusion point of the binder layer is lowered, and the viscosity of the binder coated refractory can be adjusted. The addition condensation reaction of the phenol resin of the binder layer can be started at a low temperature, and after the binder-coated refractory is filled in the mold, the binder layer can be heated in a short time. The addition condensation reaction of the phenol resin can be started and cured, and the cycle for forming the mold can be shortened.

  In the present invention, the solid phenol resin is selected from a resol type phenol resin, a novolac type phenol resin, a mixture of a resol type phenol resin and a novolac type phenol resin, and the liquid phenol resin is a resol type phenol resin, It is characterized in that it is selected from a novolac type phenol resin, a mixture of a resol type phenol resin and a novolac type phenol resin.

  Thus, as a solid phenol resin or a liquid phenol resin forming a binder layer, any of a resol type phenol resin, a novolac type phenol resin, a mixture of both can be used in any combination, A solid phenol resin binder layer can be formed in an optimal combination depending on the application.

  Moreover, in this invention, the said binder layer contains the hardening | curing agent for phenol resins, It is characterized by the above-mentioned.

  Thus, by containing the hardening | curing agent for phenol resins, the cure rate of a phenol resin can be accelerated | stimulated and the cycle which molds a casting_mold | template can be shortened more.

  In the present invention, the binder layer contains a carbonaceous material.

  Thus, when the binder layer contains a carbonaceous material, the wettability of the molten metal with respect to the molded mold can be reduced, and a mold having excellent characteristics with respect to seizure and insertion can be obtained. It can be done.

  The method for producing a mold according to the present invention includes filling the above-mentioned binder-coated refractory into a heated mold, and heating the binder-coated refractory by heat transfer from the mold, thereby producing a binder. The phenolic resin of the layer is cured.

  As described above, the binder layer on the surface of the binder-coated refractory is formed of a solid phenol resin and a liquid phenol resin, but since it is solid, the binder-coated refractory is a smooth granular material. Thus, the fluidity is good, and the binder-coated refractory can be easily filled in the mold. Since the binder layer of the binder-coated refractory is thus formed from a solid phenol resin and a liquid phenol resin, the binder layer can be adjusted so that the fusion point of the binder layer is low. The addition condensation reaction of the phenolic resin in the binder layer of the binder-coated refractory can be started at a low temperature, and the binder-coated refractory is filled in a heated mold and then molded. The heat transfer from the mold can shorten the time when the addition condensation reaction of the phenol resin in the binder layer of the binder coated refractory can be shortened, and the cycle for molding the mold can be shortened. It is.

  Another method for producing a mold according to the present invention is to fill the binder-coated refractory with the binder-coated refractory into the mold, heat the binder-coated refractory through water vapor in the mold, and form a binder layer. The phenol resin is cured.

  Since water vapor has a high latent heat of condensation, passing the water vapor through a mold filled with a binder-coated refractory transfers this latent heat when the water vapor contacts the binder-coated refractory, and the binder-coated refractory. The temperature of the refractory can be instantaneously increased, and the water vapor passes between the binder-coated refractory filled in the mold, so that the binder-coated refractory close to the mold surface of the mold is used. In addition, the binder-coated refractory far from the mold surface of the mold can be heated at the same time, and in addition to the above-described effects obtained from the low fusion point of the phenol resin in the binder layer, A mold can be manufactured in a shorter time.

  In addition, the present invention is directed to passing the steam into the mold filled with the binder-coated refractory as described above, increasing the temperature of the binder-coated refractory by the condensation latent heat of the steam, and then heating the heated gas into the mold. The condensed water in the mold is evaporated and heated above the temperature at which the phenolic resin in the binder layer of the binder-coated refractory is cured.

  By blowing water vapor into the mold filled with the binder-coated refractory, the temperature of the binder-coated refractory can be rapidly raised to near 100 ° C. by the condensation latent heat of the water vapor, and then heated. By blowing the gas into the mold, the condensed water can be quickly evaporated with this gas with less moisture, and the temperature can be raised to 100 ° C. or higher in a short time. The speed at which the temperature of the agent-coated refractory is raised can be increased, and the mold can be produced in a shorter time.

  The present invention is also characterized in that the heated gas is heated air.

  By using air in the atmosphere as the heated gas, the mold can be manufactured at low cost.

  In the present invention, the heated gas is a mixed gas of water vapor and air.

  By using a mixed gas of water vapor and air as the heated gas in this manner, the water vapor used for blowing into the mold and the air in the atmosphere can be used as they are, and the mold can be manufactured at low cost. It can be done.

  Further, the present invention is characterized in that the water vapor is superheated water vapor.

  Superheated steam is high-temperature dry steam. By using superheated steam as water vapor in this way, it is less likely that condensed water is generated excessively from water vapor in the mold, and the binder coated in the mold is coated. The speed of the temperature rise of the refractory can be increased.

  Further, the present invention is characterized in that a preheated binder-coated refractory is filled in a mold.

  By preheating the binder-coated refractory in this way, the temperature difference of the binder-coated refractory due to the temperature difference in the season such as summer and winter can be eliminated and blown into the mold. The temperature drop of the water vapor can be suppressed, and the production efficiency of the mold can be increased.

  According to the present invention, the binder layer on the surface of the binder-coated refractory is formed of a solid phenol resin and a liquid phenol resin, but since it is solid, the binder-coated refractory is a smooth granular material. In addition, the fluidity is good, and the filling property to the mold can be obtained well.

  And since the binder layer is formed from a solid phenol resin and a liquid phenol resin in this way, it can be adjusted so that the fusion point of the binder layer is lowered, and the binder coated refractory phenol Resin addition condensation reaction can be started at a low temperature, and the binder coated refractory is filled into the mold, and then the phenol resin addition condensation reaction of the binder layer is performed in a short time. Can be started and cured, and the cycle for forming the mold can be shortened.

An example of the manufacturing method of the casting_mold | template which concerns on this invention is shown, (a) (b) is sectional drawing in each process, respectively. It is sectional drawing which shows another example of the manufacturing method of the casting_mold | template which concerns on this invention. (A) is the schematic which shows the filling state of the binder coated refractory in a shaping | molding die, (b) is a graph which shows typically the temperature distribution of the binder coated refractory in a shaping | molding die. FIG. 2 shows a conical scissor for measuring the flow velocity of a binder-coated refractory, wherein (a) is a plan view and (b) is a front view.

  Embodiments of the present invention will be described below.

  In the present invention, the refractory aggregate is not particularly limited, but examples include dredged sand, mountain sand, alumina sand, olivine sand, chromite sand, zircon sand, mullite sand, other artificial sand, reclaimed sand, and the like. In addition to using these alone, it is also possible to use a mixture of plural types.

  The binder-coated refractory according to the present invention is formed by coating the surface of the particles of the refractory aggregate with a binder layer mainly composed of a phenol resin. Here, the phenol resin can be prepared by reacting phenols and aldehydes in the presence of a catalyst.

  The above phenols mean phenol and phenol derivatives, and monovalent phenols are used. For example, in addition to phenol, trifunctional compounds such as m-cresol and 3,5-xylenol, tetrafunctional compounds such as bisphenol A and dihydroxydiphenylmethane, o-cresol, p-cresol, p-ter-butylphenol, p -Bifunctional o- or p-substituted phenols such as phenylphenol, p-cumylphenol, p-nonylphenol, 2,4 or 2,6-xylenol, and further substituted with chlorine or bromine Halogenated phenols and the like can also be used. Of course, in addition to selecting and using one of these, a plurality of types can be mixed and used.

  As the aldehydes, formalin in the form of an aqueous solution is optimal, but forms such as paraformaldehyde, acetaldehyde, benzaldehyde, trioxane, and tetraoxane can also be used. It can be used by replacing with aldehyde or furfuryl alcohol.

  The blending ratio of the above phenols and aldehydes is preferably set so that the molar ratio is in the range of 1: 0.5 to 1: 3.5.

  As a reaction catalyst, when preparing a novolac-type phenol resin, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, organic acids such as oxalic acid, paratoluenesulfonic acid, benzenesulfonic acid and xylenesulfonic acid, and acetic acid Zinc or the like can be used. When preparing a resol-type phenolic resin, an alkaline earth metal oxide or hydroxide can be used, and an aliphatic group such as dimethylamine, triethylamine, butylamine, dibutylamine, tributylamine, diethylenetriamine, or dicyandiamide. Primary, secondary, tertiary amine, aliphatic amines having aromatic rings such as N, N-dimethylbenzylamine, aromatic amines such as aniline and 1,5-naphthalenediamine, ammonia, hexamethylenetetramine, etc. Other divalent metal naphthenic acids and divalent metal hydroxides can also be used.

  In the present invention, when forming the binder layer by coating the surface of the refractory aggregate particles with a phenol resin, the solid phenol resin and the liquid phenol resin are used as the phenol resin. In this way, a binder layer is formed.

  In the present invention, the solid phenol resin means that the binder-coated refractory is stored, and the binder-coated refractory is supplied to the mold in a temperature range that acts on the binder-coated refractory. It is a phenol resin showing a solid state. Since this temperature is usually in the range of 20 to 60 ° C., it is necessary to be solid at a temperature of 60 ° C. or lower, and it is preferable to use a phenol resin that is solid at a temperature of 110 ° C. or lower.

  In the present invention, the liquid phenolic resin is a phenolic resin that exhibits a liquid state in the same temperature range as described above, and is required to be liquid at a temperature of 20 ° C. or higher, preferably 0 ° C. or higher. It is preferable to use a phenol resin that is liquid. The liquid phenolic resin needs to be a liquid itself, and the liquid phenolic resin dissolved or dispersed in a solvent is not a liquid phenolic resin used in the present invention.

  And by blending and mixing the phenol resin with the refractory aggregate, a binder coated refractory with a binder layer mainly composed of the phenol resin coated on the surface of the refractory aggregate can be obtained. is there. Examples of the method for coating the surface of the refractory aggregate with the binder layer include a hot coat method, a cold coat method, a semi-hot coat method, and a powder solvent method.

  In the hot coating method, the phenol resin is added to and mixed with a refractory aggregate heated to a temperature at which the phenol resin melts, for example, 130 to 180 ° C., and the phenol resin is melted by heating with the refractory aggregate. In this method, the surface of the refractory aggregate is wetted with a binder and coated, and then cooled with the mixture kept, thereby obtaining a granular and free-flowing binder-coated refractory. Alternatively, a binder coated refractory is produced by mixing and coating a refractory aggregate heated to 130 to 180 ° C. with a phenol resin dissolved or dispersed in a solvent such as water or alcohol and volatilizing the solvent. Is the way to get.

  In the cold coating method, a phenolic resin is dispersed or dissolved in a solvent such as water or methanol to form a liquid, which is added to the particles of the refractory aggregate, mixed, and the solvent is volatilized, thereby binding the binder coated refractory. It is a way to get things.

  In the semi-hot coating method, a phenol resin dispersed or dissolved in the above solvent is added to and mixed with refractory aggregate particles heated to 50 to 90 ° C., and the solvent is volatilized to obtain a binder-coated refractory. How to get.

  In the powder solvent method, the phenol resin is pulverized, the pulverized product is added to the refractory aggregate particles, a solvent such as water or methanol is added, and the mixture is mixed to volatilize the solvent, thereby binding the binder. This is a method for obtaining a coated refractory.

  Here, in forming a binder layer by blending solid phenol resin and liquid phenol resin into a refractory aggregate, the solid phenol resin and liquid phenol resin are blended into the refractory aggregate at the same time and mixed by the above methods. Thus, coating can be performed to obtain a binder-coated refractory. Alternatively, a solid phenol resin and a liquid phenol resin can be obtained by first charging a solid phenol resin into the fireproof aggregate, coating the solid phenol resin by the above method, and then applying the liquid phenol resin and coating by the above method. A binder layer may be formed, and the liquid phenol resin is first added to the refractory aggregate, and after coating the liquid phenol resin by the above method, the solid phenol resin is added and the method described above. The binder layer made of a liquid phenol resin and a solid phenol resin may be formed by performing coating. When coating solid phenolic resin and liquid phenolic resin separately, the method of mixing phenolic resin with refractory aggregate is to mix solid phenolic resin and liquid phenolic resin with refractory aggregate by the same method. Alternatively, the solid phenol resin and the liquid phenol resin may be mixed with the refractory aggregate by another method.

  When preparing a binder-coated refractory by coating a binder layer composed of a solid phenol resin and a liquid phenol resin on the surface of the refractory aggregate as described above, the binder layer must be solid. It is. In the present invention, the binder coated refractory is stored, and the binder is applied within the temperature range that acts on the binder coated refractory until the binder coated refractory is supplied to the mold. It is necessary that the layer is solid, and since this temperature is usually in the range of 20 to 60 ° C. as described above, the binder layer needs to be solid at a temperature of 60 ° C. or less. It is preferably solid at a temperature of 110 ° C. or lower.

  When the binder layer is formed by coating only the liquid phenolic resin on the surface of the refractory aggregate, the binder layer is liquid and cannot form a solid binder layer. When the binder layer is formed by coating the resin and the liquid phenol resin, the solid binder layer can be formed by adjusting the ratio of the liquid phenol resin to the solid phenol resin. Accordingly, in the present invention, it is possible to prepare a binder-coated refractory that is more fluid than conventional binder-coated refractories.

  By adjusting the ratio of the solid phenol resin to the liquid phenol resin, a solid binder layer can be easily formed. The mixing ratio of the solid phenol resin and the liquid phenol resin needs to be adjusted depending on the softening point of the solid phenol resin, the viscosity of the liquid phenol resin, and the like. Generally, the solid phenol resin: liquid phenol resin = 98-50. : Mass range of 2-50 (total 100, the same applies hereinafter), preferably a mass ratio of 95-60: 5-40, more preferably 90-70: 10-30. is there. If a solid phenol resin with a high softening point is used, a solid binder layer can be formed even if the ratio of the liquid phenol resin is increased. If the softening point of the solid phenol resin is low, the liquid phenol resin can be formed. A solid binder layer can be formed by reducing the ratio of the resin.

  And when the binder layer of the binder-coated refractory is formed of a solid phenol resin and a liquid phenol resin in this way, the binder layer is softer than when the binder layer is formed of the solid phenol resin alone. The point is lowered, and the fusing point of the binder layer is also lower than when the binder layer is formed with the solid phenol resin alone. This is considered to be because the liquid phenolic resin is contained, and when the binder-coated refractory is heated, the liquid phenolic resin oozes out on the surface of the solid binder layer and is easily fused. It is done.

  As described above, the binder-coated refractory of the present invention can be adjusted so as to set the fusion point of the binder layer of the phenolic resin low, so that the molding cycle of the mold can be shortened as described later. In the binder-coated refractory of the present invention, the fusion point of the phenol resin binder layer is preferably 110 ° C. or lower. The binder layer is formed by setting the ratio of the solid phenol resin to the liquid phenol resin and the type of the resin so that the fusion point is below this temperature. The lower limit of the fusion point of the binder layer is not particularly set, but the fusion point is preferably 80 ° C. or higher so that blocking does not easily occur in the binder-coated refractory. . If the binder-coated refractory tends to block, it can be dealt with by storing it at a temperature lower than room temperature.

  Here, in the present invention, the solid phenolic resin may be any of a solid novolac type phenolic resin, a solid resol type phenolic resin, and a mixture of a solid novolac type phenolic resin and a solid resol type phenolic resin. Can be arbitrarily selected from the above. The liquid phenolic resin may be any of a liquid novolac phenolic resin, a liquid resol type phenolic resin, or a mixture of a liquid novolac type phenolic resin and a liquid resol type phenolic resin, and is arbitrarily selected from these. Can be used. Further, as the solid phenol resin and the liquid phenol resin, the same type of novolak type / resol type phenol resin may be used in combination, or different types of phenol resins may be used in combination.

  Moreover, a high ortho type phenol resin can be used as said novolak type phenol resin. The novolac type phenol resins can be roughly classified into a high ortho type, a high para type, and a random type depending on the ratio of the position of the methylene bond. The high ortho type has a high rate of methylene bonding at the oo ′ position, the high para type has a high rate of methylene bonding at the pp ′ position, the random type has oo ′ and opp at the methylene bonding position. The difference in the ratio of ', pp' is small. The reaction speed is in the order of high ortho type> random type> high para type. Therefore, in the present invention, it is preferable to use a high-ortho type phenol resin having a high reaction rate in order to accelerate the molding cycle of the mold.

  A high ortho novolac type phenol resin uses, for example, a divalent metal salt (for example, zinc acetate) such as Ca, Mg, Zn acetate as a catalyst, and a molar ratio of phenol and formaldehyde is 1: 0.50-0. It can be prepared by reacting at 85. At this time, the rate of methylene bonding at the ortho position tends to increase as the pH of the reaction system approaches neutral and the reaction temperature increases. Usually, if the ortho bond rate, which is the rate of methylene bond at the ortho position, is 65% or more, it is said to be a high-ortho novolac type phenol resin.

  In preparing a binder-coated refractory by coating a solid binder layer containing a solid phenol resin and a liquid phenol resin on the surface of the refractory aggregate as described above, a solid that forms a binder layer Although the quantity of a phenol resin and liquid phenol resin is not specifically limited, The range of 0.5-5.0 mass parts is preferable with respect to 100 mass parts of refractory aggregates.

  In addition to the solid phenol resin and the liquid phenol resin, the binder layer can contain a curing agent, a lubricant, a carbonaceous material, and the like for the phenol resin as necessary.

  As the curing agent for the phenol resin, hexamethylenetetramine is generally used when the phenol resin is a novolak type phenol resin. Although content of the hardening | curing agent for phenol resins is not specifically limited, The range of 5-25 mass parts is preferable with respect to 100 mass parts of novolak-type phenol resins. Thus, by containing the hardening | curing agent for phenol resins in a binder layer, the hardening rate of the phenol resin of a binder layer can be accelerated, and the shaping | molding cycle of a mold can be shortened more. . Here, when a novolac type phenol resin is used as the liquid phenol resin, the liquid phenol resin has a smaller molecular weight than the solid phenol resin, and therefore it is preferable to set a larger amount of the curing agent.

  The lubricant is contained in the binder layer in order to improve the fluidity of the binder-coated refractory. Examples of lubricants include aliphatic hydrocarbon lubricants such as paraffin wax and carnauba wax, higher aliphatic alcohols, aliphatic amide lubricants such as ethylenebisstearic acid amide and stearic acid amide, metal soap lubricants, fatty acid ester lubricants. A composite lubricant or the like can be used, and among them, a metal soap-based lubricant is preferable. As the metal soap-based lubricant, calcium stearate, barium stearate, zinc stearate, aluminum stearate, magnesium stearate, or a combination of these can be used. The content of the lubricant is not particularly limited, but a range of 0.02 to 0.15 parts by mass with respect to 100 parts by mass of the refractory aggregate is preferable.

  Moreover, the wettability of the molten metal with respect to the casting_mold | template shape | molded using a binder coated refractory can be made low by containing a carbonaceous material in a binder layer. For this reason, it is possible to reduce the seizure and insertion of the molten metal into the mold and to obtain a mold having excellent resistance to melting damage. As the carbonaceous material, any carbonaceous material such as natural graphite, artificial graphite, pitch, coke, carbon black, quiche graphite, mesophase carbon, and charcoal can be used. Is preferred. Although content of carbonaceous material is not specifically limited, The range of 0.3-10.0 mass parts is preferable with respect to 100 mass parts of phenol resin binders.

  The binder-coated refractory of the present invention obtained as described above can be used for materials such as molds, refractory bricks, wall materials, ceramics, etc., and is particularly suitable for mold applications.

  When manufacturing a mold using a binder-coated refractory, for example, by blowing the binder-coated refractory into a heated mold cavity, the binder-coated refractory is supplied into the mold. This can be done by filling the product. When the binder-coated refractory is filled in the mold thus heated, the binder-coated refractory in the cavity is heated by the heat of the mold, and the phenol of the binder layer of the binder-coated refractory is heated. The resin is cured by addition condensation reaction, and the mold can be formed by bonding the refractory aggregate with the cured phenol resin.

At this time, the binder-coated refractory filled in the cavity of the mold is heated by the heat of the mold from the binder-coated refractory close to the mold surface of the mold and the binder-coated refractory separated from the mold surface. Although it is conducted to the object, the temperature of the binder-coated refractory decreases rapidly as it goes away from the mold surface of the mold as shown in the graph of FIG. Thus, as a line L ₁ in FIG. 3 (b), at the time the temperature rise is low binder coated refractory away from the mold surface, the phenolic resin binder layer of binder coated refractory The addition condensation reaction has not started. When the fusion point of the phenol resin binder layer is high as in the conventional binder-coated refractory, the predetermined time (t ₁ ) elapses as described above, and the adhesive is separated from the mold surface. admixture coated refractory also sufficiently rise in temperature, the temperature distribution of the binder coated refractory in the cavity becomes a temperature distribution as a line L ₂ in FIG. 3 (b), finally binder coated refractory The addition condensation reaction is started on the phenol resin of the binder layer.

On the other hand, the binder layer of the binder-coated refractory of the present invention is formed from a solid phenol resin and a liquid phenol resin, and as described above, this phenol resin binder layer. The fusion point is set low. Therefore, even if the temperature distribution of the binder coated refractory in the mold is a relatively low temperature profile as a line L ₃ in FIG. 3 (b), the Nebayuizai coated refractory phenolic resin caking The agent layer is fused to start the addition condensation reaction. That is, the time t ₂ until the temperature distribution of the binder-coated refractory reaches the line L ₃ from the line L ₁ is the time t _{2 when} the temperature distribution of the binder-coated refractory reaches the line L ₂ from the line L _1. Since it is shorter than _1, the time until the phenol resin of the binder layer of the binder-coated refractory starts the addition condensation reaction after the mold is filled with the binder-coated refractory can be shortened. Is. Therefore, it is possible to shorten the time from filling the binder-coated refractory into the mold until the phenol resin in the binder layer is cured by addition condensation reaction, shortening the molding cycle of the mold. It is possible to do that.

  In addition, since the binder layer of the binder-coated refractory contains a liquid phenolic resin, the liquid phenolic resin has good wettability to the refractory aggregate, that is, the liquid phenolic resin has good affinity, and the adhesive layer adheres to the refractory aggregate That can increase the bond strength of the fireproof aggregate by the phenolic resin of the binder layer, and can mold a mold excellent in mechanical properties such as bending strength. It is.

  Here, when supplying the binder-coated refractory to the mold heated as described above, and heating and curing the phenol resin of the binder layer by the heat of the mold, in order to improve productivity There is a problem that it is necessary to raise the temperature of the mold, and when the binder-coated refractory is heated at such a high temperature, when the phenol resin of the binder layer is cured, the rapid reaction occurs. As a result, gases such as ammonia, formaldehyde, and phenol are generated, which may lead to deterioration of the working environment.

  On the other hand, the present applicant has proposed a method capable of forming a mold in a shorter time while solving such problems. That is, the binder-coated refractory is filled in the mold, and then steam is supplied and passed through the mold, and the binder-coated refractory is heated with the latent heat of condensation of the steam. In this method, the phenol resin of the agent layer is cured by addition condensation reaction, thereby producing a mold.

  An example of manufacturing such a mold using water vapor will be described with reference to FIG. As shown in FIG. 1 (a), an injection port 4 is provided on the upper surface of a molding die 1 formed by providing a cavity 3 therein, and a discharge port closed by a net 5 such as a metal mesh on the lower surface of the molding die 1. 6 is provided. This type can be divided vertically or horizontally. The binder-coated refractory 2 is stored in a hopper 7, and an air supply pipe 9 with a cock 8 is connected to the hopper 7. Then, after the nozzle port 7 a at the lower end of the hopper 7 is matched with the injection port 4 of the mold 1, the cock 8 is switched from closed to open, so that air is blown into the hopper 7 to pressurize the hopper 7. The binder-coated refractory 2 is blown into the mold 1 to fill the cavity 3 of the mold 1 with the binder-coated refractory 2. Since the discharge port 6 is blocked by the net 5, the binder coated refractory 2 does not leak from the discharge port 6. When a plurality of the inlets 4 and the outlets 6 are provided in the mold 1 as in the embodiment of FIG. 1, the binder-coated refractory 2 is inserted from one or a plurality of the inlets 4. That's fine.

  Here, the binder-coated refractory 2 of the present invention is formed by coating a refractory aggregate with a binder layer containing a solid phenol resin and a liquid phenol resin, but the binder layer is solid. Therefore, the binder-coated refractory 2 has no adhesiveness on the surface and has good fluidity. Therefore, when the binder 1 is filled with the binder-coated refractory 2 as described above, the binder-coated refractory 2 can be smoothly poured into the cavity 3 of the mold 1 so that the mold 1 has good filling properties. The binder-coated refractory 2 can be filled therein, and the occurrence of poor filling can be prevented.

  After filling the mold 1 with the binder-coated refractory 2 as described above, the hopper 7 is removed from the inlet 4 of the mold 1 and air is supplied to each inlet 4 as shown in FIG. The pipe 10 is connected. Water vapor and heated gas can be selectively supplied to the air supply pipe 10. The cock 11 of the air supply pipe 10 is opened, and water vapor is first blown into the cavity 3 of the mold 1.

  Here, saturated water vapor can be used as it is, but in the present invention, it is preferable to use superheated water vapor. Superheated steam is water vapor in a complete gas state that is further heated to saturated boiling water to a temperature equal to or higher than the boiling point, and is dry steam at 100 ° C. or higher. The superheated steam obtained by heating the saturated steam may be one that is expanded at a constant pressure without increasing the pressure, or may be pressurized steam that is increased without increasing the pressure. The temperature of the superheated steam blown into the mold 1 is not particularly limited, and the temperature of the superheated steam can be increased to about 900 ° C., so that the temperature is set between 100 and 900 ° C. as necessary. That's fine.

  Then, when steam is blown into and passed through the mold 1 in this way, the steam contacts the surface of the binder-coated refractory 2, so that the latent heat is taken away by the binder-coated refractory 2 and condensed. However, since steam has a high latent heat, the temperature of the binder-coated refractory 2 rapidly rises to around 100 ° C. due to the latent heat transferred when the steam condenses. Thus, the time during which the binder-coated refractory 2 is heated to about 100 ° C. by the heat transfer of the latent heat of water vapor is the temperature of the water vapor, the flow rate of blowing into the mold 1, and the binder in the mold 1. Although it varies depending on the filling amount of the coated refractory 2, it is usually a short time of about 3 to 30 seconds. The water vapor blown into the mold 1 from the inlet 4 heats the binder-coated refractory 2 in the mold 1 and is then exhausted from the outlet 6.

  When steam is blown into the mold 1 as described above, the temperature of the binder-coated refractory 2 can be rapidly raised to around 100 ° C. by latent heat transferred when the steam condenses. In order to further increase the temperature to 100 ° C. or higher, it is necessary to evaporate the condensed water. Then, the condensed water is evaporated by heating with steam that is blown into the mold and then passes through, and the temperature in the mold 1 rapidly rises to near the temperature of the water vapor. It can be heated at a temperature of ℃ or higher.

  Alternatively, after the temperature of the binder-coated refractory 2 has risen to around 100 ° C., the supply to the air supply pipe 10 may be switched to the heated gas, and the heated gas may be blown into the mold 1. The heated gas only needs to have a moisture content lower than that of the water vapor, and heated air can be used. For example, air in the atmosphere may be heated and supplied to the air supply pipe 10 as a heated gas. Moreover, this mixed gas can also be used as heating gas by mixing heated air with said water vapor | steam and making a moisture content low. The temperature of the heated gas is not particularly limited, and may be 50 ° C. or higher and the temperature at which the phenol resin of the binder layer of the binder coated refractory 2 is cured by addition condensation reaction. That's fine. The upper limit of temperature should just be below the temperature which decomposes | disassembles this phenol resin, and is not limited to specific temperature.

  As described above, the condensed water generated by blowing water vapor into the mold 1 is evaporated by heating with the water vapor blown thereafter, but as described above, since water vapor contains a lot of water, condensed water The efficiency of evaporating is low. Therefore, the heated gas is blown into the mold 1 in this way, and the heated gas contains less moisture than water vapor and is a dry gas having a low humidity. The condensed water produced in (1) can be evaporated and dried in a short time. Here, when the water evaporation experiment was performed with the air flow of superheated steam and heated air, the evaporation of water into the heated air becomes larger than the evaporation rate of water into the superheated steam at a temperature below 170 ° C. (T. Yosida, Hyodo, T., Ind. Eng. Chem. Process Des. Dev., 9 (2), 207-214 (1970)). As seen in this report, by blowing heated gas into the mold 1, the condensed water can be evaporated and dried in a shorter time than when steam is continuously blown.

  Accordingly, the temperature of the binder-coated refractory 2 can be raised to 100 ° C. or more in a short time after the heated gas starts to be blown into the mold 1. The speed at which the temperature in the mold 1 is increased to a temperature higher than the temperature at which the phenol resin in the agent layer is cured by addition condensation reaction can be increased. In the binder-coated refractory of the present invention, the binder layer is formed containing a solid phenol resin and a liquid phenol resin, and has a low fusion point. Therefore, combined with the fact that the binder-coated refractory starts the addition condensation reaction at a lower temperature than before, the speed of increasing the temperature of the binder-coated refractory 2 in the mold 1 is high. The mold can be manufactured in an extremely short time.

Further, the water vapor or heated gas supplied into the mold 1 passes between the particles of the binder-coated refractory 2 in the mold 1 and is discharged from the discharge port 6. The binder-coated refractory 2 is heated at the same time with water vapor or a heated gas. Therefore, binder coated refractory 2 in the mold 1, regardless of the distance from the mold surface, which is heated with a uniform temperature distribution as a line L ₃ in FIG. 3 (b), the mold A homogeneous mold having no difference in strength between the surface portion and the inside can be produced.

  Here, as described above, when condensed water is heated and evaporated with water vapor, the volume of the water vapor is reduced by condensation, the pressure decreases, and the condensed water stays in the mold 1, or is dried or heated. When the drying is performed with a heated gas, the heated gas has no volume shrinkage due to condensation and there is almost no pressure drop. Therefore, the heated gas is transferred from the inlet 4 to the outlet 6 in the mold 1. Thus, the temperature of the heated gas is applied uniformly throughout the mold 1 so that the drying and the temperature increase are performed quickly.

  The time for blowing the heated gas into the mold 1 is the temperature of the heated gas, the flow rate of blowing into the mold 1, the filling amount of the binder-coated refractory 2 in the mold 1, and the condensed water in the mold 1. Although it varies depending on the amount, it is usually a short time of about 5 to 40 seconds. Therefore, it is possible to manufacture a mold in a short time of about 10 seconds to 1 minute after the start of blowing water vapor into the mold 1.

  As described above, by supplying water vapor to the mold 1 and heating the binder-coated refractory 2, the binder-coated refractory 2 is instantaneously heated with high condensation latent heat of water vapor to cause the caking. The phenolic resin in the agent layer can be cured, and the mold can be stably produced in a short time without the need to preheat the mold 1 to a high temperature. It can be improved. In addition, even if toxic gas is generated during heating, it can be absorbed into the condensed water of water vapor, and environmental pollution can be reduced.

  Further, as shown in FIGS. 1A to 1B, when the binder-coated refractory 2 is filled in the cavity 3 of the mold 1, the binder-coated refractory 2 is heated in advance, The preheated binder-coated refractory 2 may be supplied to the mold 1 and filled in the cavity 3. By preheating the binder-coated refractory 2 in this way, the temperature drop of water vapor blown into the mold 1 can be suppressed, and the phenol resin of the binder layer is cured by addition condensation reaction. The speed at which the temperature in the mold 1 is increased to a temperature higher than the temperature at which the mold is formed can be increased, and the effect of reducing the molding time of the mold can be increased.

  The preliminary heating of the binder-coated refractory 2 can be performed, for example, in a hopper 7 that stores the binder-coated refractory 2. The temperature at which the binder-coated refractory 2 is preheated is not particularly limited, but should be a temperature at which the binder layer is softened and the fluidity of the binder-coated refractory 2 is not impaired. Is necessary, and the range of about 30 to 100 ° C. is preferable.

  In the embodiment of FIG. 2, a suction pipe 12 is connected to the discharge port 6 of the mold 1, and a vacuum pump or the like is connected to the suction pipe 12. Then, while sucking the inside of the mold 1 with the suction pipe 12, steam or heated air is blown into the mold 1 as described above. By blowing water vapor or heated air while sucking the inside of the mold 1 in this way, the water vapor or heated air is forced after passing between the particles of the binder-coated refractory 2 filled in the mold 1. In this case, water vapor and heated air are not retained in the mold 1, heating efficiency with water vapor and heated air is increased, and a mold can be manufactured in a shorter time. It will be possible.

  In each of the above embodiments, after the binder-coated refractory is blown into the mold and filled, water vapor is immediately supplied to the mold, and the binder-coated refractory in the mold is heated with water vapor. The phenolic resin in the binder layer is cured, but the heated coated mold is filled with the binder-coated refractory and left for a predetermined time, and then water vapor is supplied to the mold. Then, the binder-coated refractory in the mold may be heated with steam.

  In this way, after filling the heated mold with the binder-coated refractory, if left for a predetermined time, heat is transferred from the mold surface of the mold to the binder-coated refractory in the mold. The portion of the binder coated refractory that is in contact with the mold surface of the mold is heated, and curing proceeds to the phenol resin of the binder layer of this portion. After that, by supplying water vapor to the mold and allowing it to pass, the entire binder-coated refractory in the mold can be heated with water vapor. Of the binder-coated refractory, the mold of the mold Since the portion in contact with the surface has a large thermal history, the surface of the mold to be molded is further cured, and a dense skin layer is formed on the surface. For this reason, it is possible to mold a mold having high surface smoothness and high strength.

  Here, the heating temperature of the mold is required to be equal to or higher than the temperature at which the phenol resin in the binder layer of the binder-coated refractory starts the addition condensation reaction, and preferably 110 ° C. or higher. The upper limit of the heating temperature of the mold is not particularly high as long as the phenol resin of the binder layer is not decomposed, and is not particularly set, but is preferably 350 ° C. or lower. In addition, after the filling of the binder-coated refractory into the mold, the standing time until the supply of water vapor to the mold varies depending on the temperature of the mold, the size and thickness of the mold, etc. It is preferable that it is 10 seconds or more. If the standing time is short, the effect of forming a skin layer on the surface of the mold cannot be obtained sufficiently. On the contrary, if this standing time is long, the effect of the present invention for shortening the molding cycle is impaired, so the standing time is preferably 70 seconds or less.

  In the above embodiment, after steam is supplied to the mold filled with the binder-coated refractory and the binder-coated refractory is heated to mold the mold and the supply of steam is stopped. The mold is immediately opened and the mold is taken out. However, when a heated mold is used, after the supply of water vapor is stopped in this way, the mold is opened after being left for a predetermined time. You may make it take out.

  After the supply of water vapor is stopped in this manner and the heating of the binder-coated refractory with water vapor is finished, if the binder-coated refractory is left in the heated mold for a predetermined time, the viscosity in the mold is reduced. Of the binder-coated refractory, the surface portion in contact with the mold surface of the mold is continuously heated by heat transfer from the mold. Therefore, the portion of the binder-coated refractory that is in contact with the mold surface of the mold has a large thermal history, so that the mold to be molded is more hardened on the surface, and the surface has a dense skin. A layer will be formed. For this reason, it is possible to mold a mold having high surface smoothness and high strength.

  Here, the heating temperature of the mold is required to be equal to or higher than the temperature at which the phenol resin of the binder layer of the binder-coated refractory continues the addition condensation reaction, and is preferably 110 ° C. or higher. The upper limit of the heating temperature of the mold may not be a high temperature at which the phenol resin of the binder layer is decomposed, but is preferably 350 ° C. or lower. In addition, the standing time until the mold is taken out from the mold after the supply of water vapor to the mold is changed depending on the temperature of the mold, the size and thickness of the mold, and is preferably 10 seconds or more. . If the standing time is short, the effect of forming a skin layer on the surface of the mold cannot be obtained sufficiently. On the contrary, if this standing time is long, the effect of the present invention for shortening the molding cycle is impaired, so the standing time is preferably 50 seconds or less.

  Next, the present invention will be specifically described with reference to examples.

(Preparation of solid novolac type phenolic resin A)
A reaction vessel was charged with 940 parts by mass of phenol, 665 parts by mass of formalin having a concentration of 37% by mass, 5.6 parts by mass of oxalic acid as a catalyst, refluxed for about 60 minutes, and allowed to react for 180 minutes. Thereafter, the temperature was raised to 180 ° C., and water and unreacted phenol were distilled off to obtain a solid novolac-type phenol resin A.

  This solid novolac type phenol resin A had a softening point of 92 ° C., an ortho bond ratio of 50.5%, and a gelation time at 150 ° C. of 86 seconds.

(Preparation of solid high ortho novolak type phenol resin B)
A reaction vessel was charged with 940 parts by mass of phenol, 567 parts by mass of formalin having a concentration of 37% by mass, and 2.5 parts by mass of zinc acetate as a catalyst. The reaction was allowed to reflux for about 60 minutes and allowed to react for 180 minutes. Thereafter, the temperature was raised to about 180 ° C. over 180 minutes, and water and unreacted phenol were distilled off to obtain a solid high ortho novolac type phenol resin B.

  This solid high ortho novolac type phenol resin B had a softening point of 92 ° C., an ortho bond rate of 84.8%, and a gelation time at 150 ° C. of 25 seconds.

(Preparation of liquid novolac type phenolic resin C)
A reaction vessel was charged with 940 parts by mass of phenol, 527 parts by mass of formalin having a concentration of 37% by mass, and 4.7 parts by mass of oxalic acid as a catalyst. The reaction was allowed to reflux for about 60 minutes and allowed to react for 180 minutes. Thereafter, the liquid was removed at normal pressure until the internal temperature reached 120 ° C. to obtain a liquid novolac-type phenol resin C.

  This liquid novolac type phenol resin C had a viscosity at 25 ° C. of 20.5 Pa · s, a non-volatile content at 135 ° C. (JIS K 6910) of 80.5% by mass, and a gelation time at 150 ° C. of 240 seconds.

(Preparation of solid high ortho novolac type phenol resin D)
A reaction vessel was charged with 940 parts by mass of phenol, 446 parts by mass of formalin having a concentration of 37% by mass, and 2.5 parts by mass of zinc acetate as a catalyst. The reaction was allowed to reflux for about 60 minutes and allowed to react for 180 minutes. Thereafter, the temperature was raised to about 180 ° C. over 180 minutes, and water and unreacted phenol were distilled off to obtain a solid high ortho novolac type phenol resin D.

  This solid high ortho novolak type phenol resin D had a softening point of 73 ° C., an ortho bond rate of 85.3%, and a gelation time at 150 ° C. of 37 seconds. The solid high ortho novolak type phenol resin D has an ortho bond rate higher than that of the solid high ortho novolak type phenol resin B, but the gelation time is longer than that of the solid high ortho novolak type phenol resin B because of its low molecular weight. Because.

(Preparation of solid resol type phenol resin E)
A reaction vessel is charged with 564 parts by weight of phenol, 681 parts by weight of formalin with a concentration of 37% by weight, and 163 parts by weight of ammonia water with a concentration of 25% by weight as a catalyst. The reaction was carried out at this temperature for 5 hours. Next, the pressure was reduced to 0.02 MPa (150 Torr), and 450 ml of liquid was removed. Thereafter, the reaction product was discharged into a stainless steel vat, and the vat was put in a freezer set at −15 ° C. and frozen. Next, this frozen product was crushed to a particle size of 2 mm or less with a crusher, and dried immediately after crushing with a fluidized bed drier to obtain a solid resol type phenol resin E.

  This solid resol type phenol resin E had a softening point of 83 ° C. and a gelation time at 150 ° C. of 105 seconds.

(Preparation of liquid resol type phenol resin F)
A reaction vessel is charged with 564 parts by weight of phenol, 1500 parts by weight of 37% by weight formalin, and 30 parts by weight of 48% by weight aqueous caustic soda as a catalyst. The reaction was continued for 150 minutes. Next, after cooling to 50 ° C., the mixture was neutralized by adjusting the pH to 6.5 with a 10 mass% hydrochloric acid aqueous solution. Next, the pressure was reduced to 0.009 MPa (70 Torr) and the liquid was removed to 70 ° C., followed by cooling to obtain a liquid resol type phenol resin F.

  This liquid resol type phenol resin F has a viscosity at 25 ° C. of 400 mPa · s, a non-volatile content at 135 ° C. (JIS K 6910) of 76% by mass, a gelation time at 150 ° C. of 220 seconds, and a water miscibility of 5 It was twice.

  Here, the measurement of gelation temperature about said solid phenol resin was performed based on JACT test method RS-5 "gelation time test method". This JACT test method RS-5 conforms to JIS K 6910 (1995) “Test method for powdered phenolic resin for shell mold”. A spatula is placed on a steel plate and the steel plate and spatula are heated to 150 ° C. ± 1 ° C. After that, about 0.5 g of the sample is placed on the steel plate and at the same time, the stopwatch is pushed, and the sample is spread in a circle with a diameter of about 3 cm with a spatula. The kneading was carried out while pressing evenly, and the time until no yarn was pulled between the sample and the spatula was measured. Then, this operation is performed three times or more, and the average time is expressed in seconds to obtain the gelation time of the sample. In addition, about novolak-type phenol resin AD, the gelation time is measured by using 15 parts by mass of hexamethylenetetramine as a curing agent and mixing well with 100 parts by mass of the phenol resin powder as a sample. It was.

(Examples 1-5)
30 kg of flattered cinnabar sand is heated to 130 ° C. and charged into a whirl mixer, and the solid novolac type phenol resin shown in Table 1 is added in the amount shown in Table 1 and mixed for 30 seconds. A solution obtained by dispersing or dissolving the novolak type phenol resin and hexamethylenetetramine in the blending amounts shown in Table 1 was added and mixed until the lump of sand grains collapsed. Next, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to obtain a binder-coated refractory having a binder content (including hexamethylenetetramine; the same applies hereinafter) of 2.3 mass%. Obtained.

  The binder-coated refractory obtained in this way was a smooth particle with a solid binder layer on the surface.

(Comparative Examples 1-2)
30 kg of flattered cinnabar is heated to 140 ° C. and charged into a whirl mixer, and 600 g of a solid novolac phenol resin shown in Table 1 is added thereto, mixed for 30 seconds, and further 90 g of hexamethylenetetramine dissolved in 600 g of water. Was added and mixed until the lump of sand grains collapsed. Next, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to obtain a binder-coated refractory having a binder content of 2.2% by mass.

  The binder-coated refractory obtained in this way was a smooth particle with a solid binder layer on the surface.

  About the binder coated refractory prepared as described above, the fusion point of the binder layer was measured in accordance with JACT test method C-1 “Fusion point test method”.

  Moreover, the flow-down velocity was measured for these binder-coated refractories. The flow velocity was measured using a conical rod 20 having a conical hole 21 as shown in FIGS. First, the conical rod 20 is placed on a horizontal surface so that the lower surface opening of the hole 21 is blocked, and the binder-coated refractory is poured from the paper cup into the hole 21 of the conical rod 20, and the sandbag is used to Scrape and remove the binder-coated refractory that rises up. Next, the conical rod 20 was lifted, and measurement was started by a stopwatch when the conical rod 20 was separated from the horizontal plane, and the time until the binder coated refractory was finished from the lower surface opening of the hole 21 was measured. And this test was done twice or more and the average value was made into the flow-down speed.

  Moreover, the angle of repose was measured about these binder coated refractories. The angle of repose was measured using an “AOD powder characteristic measuring device” manufactured by Tsutsui Rika Instruments Co., Ltd. In addition, the measurement of the flow velocity and the angle of repose were performed in an atmosphere at 25 ° C.

  Furthermore, based on the bending strength test method of JIS K6910, the test piece was shape | molded using said binder coated refractory, and bending strength was measured.

Furthermore, the test piece was shape | molded using said binder coated refractory, and hot bending strength was measured. That is, a metal mold having a mold size of 25 × 25 × 200 mm is preheated to 250 ° C., and a binder-coated refractory is blown into the mold at a gauge pressure of 0.1 MPa from one end in the longitudinal direction. Demolded in seconds. And about the test piece produced in this way, bending strength (hot bending strength) was measured 5 seconds after mold removal. And the rigidity was calculated | required by the following formula from said bending strength and hot bending strength.
Rigidity (%) = (Hot bending strength / Bending strength) × 100
The results are shown in Table 1.

  As seen in Table 1, the binder-coated refractories of Examples 1 to 5 in which the binder layer is formed of a solid phenol resin and a liquid phenol resin form the binder layer of a solid phenol resin. It is confirmed that the fusing point of the binder layer can be set lower than those of Comparative Examples 1 and 2 which are made. Moreover, the binder-coated refractories of Examples 1 to 5 have a flow velocity and angle of repose equivalent to those of the binder-coated refractories of Comparative Examples 1 and 2 in which the binder layer is formed of a solid phenol resin. The binder-coated refractory of the present invention in which a binder layer is formed of a solid phenol resin and a liquid phenol resin is excellent in fluidity as in the case of a conventional binder-coated refractory. It is confirmed that the filling property can be obtained satisfactorily.

(Examples 6 to 12)
Heat 30 kg of flattered cinnabar to 130 ° C. and add to a whirl mixer, add solid novolac phenolic resin or resol type phenolic resin shown in Table 2 in the amount shown in Table 2, mix for 30 seconds, and then add 600 g of water. A liquid novolac-type phenol resin or resol-type phenol resin in Table 2 and a liquid in which hexamethylenetetramine was dispersed or dissolved in the blending amount shown in Table 2 as needed were added, and mixed until the lump of sand grains collapsed. Next, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to obtain a binder-coated refractory having a binder content of 2.3 mass%.

  The binder-coated refractory obtained in this way was a smooth particle with a solid binder layer on the surface.

(Comparative Examples 3-4)
30 kg of flattered cinnabar was heated to 140 ° C. and charged into a whirl mixer, to which 600 g of a solid novolac type phenol resin and a resol type phenol resin shown in Table 2 were added, and mixed until a lump of sand grains collapsed. Next, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to obtain a binder-coated refractory having a binder content of 2.3 mass%.

  The binder-coated refractory obtained in this way was a smooth particle with a solid binder layer on the surface.

  For the binder-coated refractories of Examples 6 to 12 and Comparative Examples 3 to 4 prepared as described above, in the same manner as described above, the fusion point, the flow velocity, the angle of repose, the bending strength, and the hot bending strength. The stiffness was measured and the stiffness was determined. The results are shown in Table 2.

  As seen in Table 2, Examples 6 to 12 were formed by combining a solid novolak type phenolic resin or resol type phenolic resin with a liquid novolak type phenolic resin or resol type phenolic resin to form a binder layer. The binder-coated refractory has a bonding point of the binder layer rather than that of Comparative Examples 3 to 4 in which the binder layer is formed of a solid novolac type phenol resin and a resol type phenol resin. It is confirmed that it can be set low. The binder-coated refractories of Examples 6 to 12 have a flow velocity and angle of repose equivalent to those of the binder-coated refractories of Comparative Examples 3 to 4, and are solid phenol resin and liquid phenol resin. It is confirmed that the binder-coated refractory of the present invention having a binder layer is excellent in fluidity as in the case of conventional binder-coated refractories, and can be satisfactorily filled into a mold. Is done.

(Examples 13 to 16)
30 kg of flattered cinnabar is heated to 130 ° C. and charged into a whirl mixer. To this, solid novolac type phenol resin or resol type phenol resin shown in Table 3 is added in the amount shown in Table 3, mixed for 30 seconds, and then added to 600 g of water. A liquid obtained by dispersing or dissolving the liquid resol type phenol resin in Table 3 in the blending amount shown in Table 3 was added and mixed until the lump of sand grains collapsed. Next, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to obtain a binder-coated refractory having a binder content of 2.3 mass%.

  The binder-coated refractory obtained in this way was a smooth particle with a solid binder layer on the surface.

  For the binder-coated refractories of Examples 13 to 16 prepared as described above, the fusion point, flow velocity, repose angle, bending strength, hot bending strength were measured in the same manner as described above, and The rate was determined.

Furthermore, blocking tests were performed as follows for the binder-coated refractories of Examples 13 to 16 and Comparative Example 4. In a room with a room temperature of 20 ° C. and a humidity of 65% RH, a pipe made of polyvinyl chloride with a diameter (inner diameter) of 50 mm and a length of 14 cm is placed on a stainless steel plate, and the lower end of the pipe is closed with a stainless steel plate. Put 140g of binder-coated refractory into the pipe and insert a column weight with a diameter of 49.5mm and weight of 1580g into the pipe. Compressed with. After 24 hours, the weight was removed, the pipe was lifted from the stainless steel plate, and the binder-coated refractory in the pipe was discharged from the lower end of the pipe. At this time, the case where all of the binder-coated refractory material was taken out of the pipe without being agglomerated was “○: No blocking”, and the binder-coated refractory material was gathered in a cylindrical shape from the pipe. However, “△: Mild blocking” refers to the case where it can be easily broken if pressed with a finger, and “X: Blocking” refers to the case where the binder-coated refractory comes out in a cylindrical shape from the pipe and does not collapse even when pressed with a finger. evaluated.
The results are shown in Table 3.

  As seen in Table 3, it is confirmed that the binder-coated refractories of Examples 13 to 16 can set the fusion point of the binder layer low. In addition, the binder-coated refractories of Examples 13 to 16 have the same flow rate, angle of repose, and blocking properties as those of Comparative Example 4 in which the binder layer is formed of a solid phenol resin. The binder-coated refractory of the present invention, in which a binder layer is formed with a liquid phenolic resin, is excellent in fluidity like the conventional binder-coated refractory, and has good filling properties in the mold. It is confirmed that it can be obtained.

(Examples 17 to 20, Comparative Example 5)
A metal mold having a molding dimension of 150 mm in length, 100 mm in width, and 20 mm in thickness was preheated to 250 ° C., and the binder-coated fireproofed binders of Examples 2, 7, 8, 9 and Comparative Example 3 were placed in this mold. The object was blown in at an air pressure of a gauge pressure of 0.1 MPa to produce a test mold. After blowing the binder coated refractory, the mold is opened after 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, and whether the mold can be taken out. A test was conducted. The results are shown in Table 4. In Table 4, “◯” indicates that the mold can be easily taken out without deformation, “Δ” indicates that the mold can be taken out but the mold has deformed, and “×” indicates that the mold is separated and cannot be taken out. , Indicate.

  As seen in Table 4, in Comparative Example 5, it takes 50 seconds or more to remove the mold from the mold, whereas in Examples 17 to 20, the mold can be removed from the mold in 20 to 40 seconds. Therefore, the molding time can be shortened.

(Examples 21 to 24, Comparative Example 6)
Using the binder-coated refractories of Examples 2, 7.8 and 9 and Comparative Example 3 described above, a mold was prepared by a method of heating by blowing water vapor. That is, in the apparatus of FIG. 1, a mold having a cavity size of 150 mm in length, 100 mm in width, and 20 mm in thickness is preheated to 120 ° C., and first, a binder-coated refractory is used with a gauge pressure of 0 Filled by blowing into the mold with air pressure of 1 MPa.

  After that, an air supply pipe is connected to the mold, and saturated steam having a gauge pressure of 0.4 MPa and a temperature of 143 ° C. generated by a boiler is heated by a superheated steam generator (“GE-100” manufactured by Nomura Engineering Co., Ltd.). The superheated steam prepared at 350 ° C. and the gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and this steam was blown into the mold.

  Then, water vapor is blown into the mold for 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, and 30 seconds, respectively. A test was conducted to determine whether the mold could be removed. The results are shown in Table 5. The criteria for “◯”, “Δ”, and “×” in Table 5 are the same as above.

  As seen in Table 5, in Comparative Example 6, the time required to take out the mold from the mold is 25 seconds. On the other hand, in Examples 21 to 24, the mold can be taken out from the mold in 10 to 20 seconds, and the molding time can be shortened. Also, compared with Examples 17 to 20 in Table 4 above. The molding time can be further shortened.

(Example 25)
A mold was prepared by blowing steam and heating with a heated gas. That is, the mold 1 as shown in FIG. 1 in which the size of the cavity 3 was 30 cm × 10 cm × 4 cm was preheated to 150 ° C. and used. Temperature sensors are provided at the three discharge ports 6 on the lower surface of the mold 1 so that the temperature of the gas discharged from the discharge port 6 can be measured.

  First, the hopper 7 was connected to the central inlet 4 among the three inlets 4 on the upper surface of the mold 1 and the other two inlets 4 were closed, and the binder coated obtained in Example 8 was used. The refractory 2 was filled by blowing into the mold 1 with an air pressure of 0.2 MPa.

  Next, an air supply pipe 10 is connected to the three inlets 4 on the upper surface of the mold 1, and saturated steam having a pressure of 0.4 MPa and a temperature of 143 ° C. generated by a boiler is supplied to a superheated steam generator (Nomura Tech. Superheated steam at 350 ° C. and 0.45 MPa obtained by heating with “GE-100” manufactured by Co., Ltd. was supplied to the supply pipe 10 at a flow rate of 80 kg / h and blown into the mold 1 for 10 seconds.

Immediately thereafter, the supply to the air supply pipe 10 was switched to the heated gas, and heated air at 350 ° C. was blown into the mold 1 as the heated gas for 20 seconds. Here, the heated air is air having a relative humidity of 63% RH at 25 ° C. heated to 350 ° C. with a hot air generator (“TSK-31” manufactured by Taketsuna Manufacturing Co., Ltd.), and is 5.7 m ³ / It was blown into the mold 1 at a flow rate of minutes.

In this way, the superheated steam at 350 ° C. was blown into the mold 1 at a flow rate of 80 kg / h for 10 seconds, and then heated air at 350 ° C. at a flow rate of 5.7 m ³ / min for 20 seconds. The coated refractory 2 was heated to produce a mold, and the mold 1 was broken to obtain a 30 cm × 10 cm × 4 cm mold.

(Example 26)
Example 25 Except that superheated steam at 350 ° C. was blown into the mold 1 at a flow rate of 80 kg / h for 15 seconds, and then heated air at 350 ° C. at a flow rate of 5.7 m ³ / min for 15 seconds. In the same manner, a template was obtained.

(Example 27)
Example 25 Except that superheated steam at 350 ° C. was blown into the mold 1 for 20 seconds at a flow rate of 80 kg / h, and then heated air at 350 ° C. for 10 seconds at a flow rate of 5.7 m ³ / min. In the same manner, a template was obtained.

(Example 28)
A mold was obtained in the same manner as in Example 25 except that the binder-coated refractory used was the one obtained in Example 9.

(Example 29)
A mold was obtained in the same manner as in Example 26 except that the binder-coated refractory used was the one obtained in Example 9.

(Example 30)
A mold was obtained in the same manner as in Example 27 except that the binder-coated refractory used was obtained in Example 9.

(Example 31)
Using the binder-coated refractory obtained in Example 9, superheated steam at 350 ° C. was blown into the mold 1 at a flow rate of 80 kg / h for 10 seconds, followed by superheated steam at 350 ° C. at 40 kg / h. A mold was obtained in the same manner as in Example 25 except that the mixed gas was mixed at a flow rate of 350 ° C. and heated air of 350 ° C. at a flow rate of 3 m ³ / min and the mixed gas was blown into the mold 1 for 20 seconds.

(Example 32)
Using the binder-coated refractory obtained in Example 9, superheated steam at 350 ° C. was blown into the mold 1 at a flow rate of 80 kg / h for 15 seconds, followed by superheated steam at 350 ° C. as a heating gas. Was mixed in a flow rate of 40 kg / h and heated air of 350 ° C. at a flow rate of 3 m ³ / min, and the mixed gas was blown into the mold 1 for 15 seconds. Obtained.

(Example 33)
Using the binder-coated refractory obtained in Example 9, 350 ° C. superheated steam was blown into the mold 1 at a flow rate of 80 kg / h for 20 seconds, followed by 350 ° C. superheated steam at 40 kg / h. A mold was obtained in the same manner as in Example 25 except that the mixed gas was mixed at a flow rate of 350 ° C. and heated air of 350 ° C. at a flow rate of 3 m ³ / min and the mixed gas was blown into the mold 1 for 10 seconds.

(Comparative Example 7)
As in Example 25, except that the binder-coated refractory obtained in Comparative Example 3 was used and superheated steam at 350 ° C. was blown into the mold 1 at a flow rate of 80 kg / h for 30 seconds. To obtain a mold.

(Comparative Example 8)
As in Example 25, except that the binder-coated refractory obtained in Comparative Example 4 was used and superheated steam at 350 ° C. was blown into the mold 1 at a flow rate of 80 kg / h for 30 seconds. To obtain a mold.

  In the above Examples 25 to 33 and Comparative Examples 7 to 8, the temperature of the three outlets 6 of the mold 1 at the end of superheated steam blowing and the end of blowing heated air (mixed gas), The temperatures of the three outlets 6 of the mold 1 were measured with temperature sensors, and the average values are shown in Table 6. Further, the odor when the mold is taken out from the mold 1 is evaluated based on the odor sense of the operator, and the results are shown in Table 6. Further, the mass of the removed mold was measured, and the bending strength of the mold was measured according to the bending strength test method of JIS K 6910. The results are shown in Table 6.

  As seen in Table 6, in Comparative Examples 4 to 5 in which superheated steam was blown for 30 seconds, the temperature at the end point was 114 to 116 ° C., whereas heated air ( In Examples 21 to 26 in which the gas mixture was blown for a total of 30 seconds, the temperature at the end time was 151 to 160 ° C., and it was confirmed that the rate of temperature increase in the mold was increased. . Moreover, it is also confirmed that the molds obtained in Examples 21 to 26 have higher strength than those of Comparative Examples 4 to 5.

(Example 34)
Using the binder-coated refractory 2 obtained in Example 8 and blowing and filling the binder-coated refractory 2 in the mold 1 heated to 150 ° C. in the same manner as in Example 25, Immediately, 350 ° C. and 0.45 MPa superheated steam were blown into the mold 1 at a flow rate of 80 kg / h for 20 seconds. Next, after stopping the blowing of superheated steam, it is held for 20 seconds as it is, and the binder-coated refractory 2 in the mold 1 is heated by heat transfer from the mold 1 and then the mold 1 is cracked. As a result, a mold of 30 cm × 10 cm × 4 cm was obtained.

(Example 35)
Using the binder-coated refractory 2 obtained in Example 8 and blowing and filling the binder-coated refractory 2 in the mold 1 heated to 150 ° C. in the same manner as in Example 25, The binder-coated refractory 2 in the mold 1 was heated by heat transfer from the mold 1 while being held for 20 seconds. Next, in the same manner as in Example 25, after superheated steam of 350 ° C. and 0.45 MPa was blown into the mold 1 at a flow rate of 80 kg / h for 20 seconds, the mold 1 was immediately broken to obtain 30 cm × 10 cm × 4 cm. A mold was obtained.

  In the above Examples 34 to 35 and Comparative Examples 7 to 8, when the temperatures of the three outlets 6 of the mold 1 at the end of the superheated steam blowing are measured by the temperature sensor, and the mold is taken out from the mold 1 The odor of the worker was evaluated by the sense of smell of the worker. Further, the mass and bending strength of the removed mold were measured. These results are shown in Table 7.

  The bending strengths of the molds of Examples 34 to 35 shown in Table 7 are higher than those of Examples 25 to 28 using the same binder-coated refractory, and before the steam was blown in, It is confirmed that the strength of the mold is improved by holding so that heating is performed by heat transfer from the mold after blowing.

1 Mold 2 Binder coated refractory

Claims (12)

The surface of the refractory aggregate is covered with a solid binder layer containing a solid phenol resin and a liquid phenol resin, and the solid binder layer has a fusion point of 80 ° C. or higher and 110 ° C. or lower. A binder-coated refractory characterized by being characterized in that.
  The solid phenol resin is selected from a resol type phenol resin, a novolac type phenol resin, a mixture of a resol type phenol resin and a novolac type phenol resin, and a liquid phenol resin is a resol type phenol resin, a novolac type phenol resin, a resol type phenol resin. 2. The binder-coated refractory according to claim 1, wherein the binder-coated refractory is selected from a mixture of a phenolic resin and a novolac type phenolic resin.   The binder-coated refractory according to claim 1 or 2, wherein the binder layer contains a curing agent for a phenol resin.   The binder-coated refractory according to any one of claims 1 to 3, wherein the binder layer contains a carbonaceous material.   A mold comprising the binder-coated refractory according to any one of claims 1 to 4 formed by bonding with a cured product of a phenol resin of a binder layer.   The binder-coated refractory according to any one of claims 1 to 4 is filled in a heated mold, and the binder-coated refractory is heated by heat transfer from the mold to form a binder layer. A method for producing a mold, comprising curing a phenol resin.   The binder-coated refractory according to any one of claims 1 to 4 is filled in a molding die, and the binder-coated refractory is heated through water vapor in the molding die, and the phenol resin of the binder layer is added. A method for producing a mold, characterized by curing.   Steam is passed through the mold filled with the binder-coated refractory, the temperature of the binder-coated refractory is increased by the latent heat of condensation of the water vapor, and then the heated gas is passed through the mold, The method for producing a casting mold according to claim 7, wherein the condensed water is evaporated and heated to a temperature at which the phenol resin of the binder layer of the binder-coated refractory is cured.   The method for producing a mold according to claim 8, wherein the heated gas is heated air.   The method for producing a mold according to claim 8, wherein the heated gas is a mixed gas of water vapor and air.   The method for producing a mold according to claim 7, wherein the water vapor is superheated water vapor.   The method for producing a mold according to any one of claims 7 to 11, wherein a preheated binder-coated refractory is filled in a mold.

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