WO2019070051A1

WO2019070051A1 - Mold material and manufacturing method therefor, mold and manufacturing method therefor, and molding sand regeneration method

Info

Publication number: WO2019070051A1
Application number: PCT/JP2018/037354
Authority: WO
Inventors: 文幸小川; 哲也浦
Original assignee: 旭有機材株式会社
Priority date: 2017-10-06
Filing date: 2018-10-05
Publication date: 2019-04-11
Also published as: JP7252897B2; JPWO2019070051A1

Abstract

The present invention provides a green molding material that results in an end-product mold exhibiting excellent collapsibility, makes it easy to recycle the sand recovered from a post-casting mold, and is unlikely to cause odor issues. The green molding material is obtained by forming an organic compound-containing solid coating layer on the surface of molding sand and then coating the molding sand, on which the coating layer has been formed, with a liquid binder composition that contains a water-soluble inorganic binder.

Description

Mold material and method for manufacturing the same, mold and method for manufacturing the same, and method for regenerating casting sand

The present invention relates to a mold material and a method of manufacturing the same, a mold and a method of manufacturing the same, and a method of regenerating casting sand.

Conventionally, as one of the molds used for casting molten metal, a target shape is obtained by using a coated sand (mold material) formed by coating a molding sand made of a refractory aggregate with a predetermined binder. The one obtained by molding into is used. Specifically, in "Casting Engineering Handbook" edited by the Japan Casting Engineering Association, pages 78 to 90, inorganic resins such as water glass, phenol resin and the like can be used as a binder in such coated sands. Organic binders made of resins such as furan resin and urethane resin have been clarified, and methods of forming self-hardening molds using these binders have also been clarified.

For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2012-76115), a solid coating layer containing a predetermined water-soluble inorganic compound such as water glass as a caking agent is formed on the surface of a fireproof aggregate (casting sand). A well-flowed, binder-coated refractory (coated sand) that is coated is disclosed. In the same document, such caking agent coated refractory (coated sand) having good fluidity is filled in the molding cavity of a molding die for mold making, and then water vapor is contained in the molding die. It has also been clarified that by aeration, solidification of the binder-coated refractory (coated sand) proceeds, and a target mold is obtained.

Here, the coated sand (template material) configured using an inorganic caking agent such as water glass has an organic content compared to the coated sand (template material) using an organic caking agent It is conventionally known that generation of various gases due to heat during molding or casting is advantageously suppressed, and problems such as odor are less likely to occur. However, in the coated sand (mold material) constructed using a conventional inorganic binder such as that disclosed in Patent Document 1, casting sand (refractory aggregate) is obtained from the mold after casting ) Is recovered and the recovered sand is to be regenerated by roasting, the inorganic caking agent remaining on the surface of the recovered sand does not burn but it is sintered in reverse and cast sand (refractory aggregate) The problem is that it is difficult to regenerate because it sticks firmly to the surface of. In particular, in coated sand (mould material) using water glass as an inorganic caking agent, the water glass becomes vitrified by the heat during casting, and the cast sand collected after casting is roasted and polished Even if implemented, there is a problem that it is very difficult to remove the vitrified water glass on the sand surface. In addition, in the conventional coated sand (template material) using an inorganic binder, the disintegrability of the template obtained using it is not sufficient, and there is still room for improvement in this respect. It is

JP 2012-76115 A

Here, the present invention has been made against the background described above, and the problem to be solved is a mold material which is excellent in the collapsibility of the mold and which facilitates the regeneration of foundry sand. It is to provide. Further, the present invention provides a method capable of advantageously manufacturing a mold material having such excellent properties, a mold using such a mold material, a method of manufacturing the same, and a method of regenerating cast sand. Is the problem to be solved.

And, in order to solve the problems described above, the present invention can be suitably implemented in various aspects as listed below, and each aspect described below is adopted in any combination. It is possible. It should be noted that aspects or technical features of the present invention can be recognized based on the inventive concept that can be grasped from the description of the entire specification without being limited to the following description. It should be understood.

(1) Foundry sand coated with a solid coating layer containing an organic compound,
A wet mold material characterized in that it is coated with a liquid caking agent composition containing a water-soluble inorganic caking agent.
(2) The mold material according to the above-mentioned (1), wherein the thickness of the solid coating layer is 0.1 to 6 μm.
(3) The above embodiment (the organic compound is at least one selected from the group consisting of a cross-linking curable resin and a cured product thereof, a thermoplastic resin, and a carbohydrate)
1) or the mold material as described in the said aspect (2).
(4) The mold material according to the above aspect (3), wherein the crosslinkable curable resin is a phenol resin.
(5) The template material according to any one of the aspects (1) to (4), wherein the organic compound is a polymer compound having a weight average molecular weight of 300 or more.
(6) The mold material according to any one of the above aspects (1) to (5), wherein the solubility of the organic compound in 100 g of water at 25 ° C. is 1% by mass or less.
(7) The embodiment wherein the solid coating layer contains a coupling agent (1
The template material according to any one of the above aspects (6).
(8) The mold according to any one of the above aspects (1) to (7), wherein the solid content of the water-soluble inorganic binder in the liquid caking agent composition is 10 to 80% by mass. Material (9) The mold material according to any one of the above embodiments (1) to (8), wherein the liquid binder composition contains a coupling agent.
(10) The embodiment (1), wherein the liquid caking agent composition contains inorganic oxide particles
The mold material according to any one of the above aspects (9).
(11) The template material according to the above aspect (10), wherein the inorganic oxide particles are silicon dioxide particles.
(12) The mold material according to any one of the above aspects (1) to (11), wherein the liquid caking agent composition contains a moisture resistance improver.
(13) The mold material according to any one of the modes (1) to (12), wherein the water-soluble inorganic binder is water glass.
(14) The mold material according to any one of the modes (1) to (13), wherein the liquid binder composition contains water.
(15) A mold formed using the mold material according to any one of the above aspects (1) to (14).
(16) The mold according to the above mode (15), wherein the amount of gas generated when heated at 1000 ° C. for 240 seconds is 3 to 30 ml per 1 g.
(17) forming a solid coating layer containing an organic compound on the surface of the molding sand;
Adding a liquid caking agent composition containing a water-soluble inorganic caking agent to the foundry sand having the solid coating layer formed thereon, and kneading or mixing;
A method of producing a wet mold material having
(18) After the organic compound is a crosslink-curable resin, and the solid coating layer is formed on the surface of the casting sand, the crosslink-curable resin contained in the solid coating layer is cured. The method for producing a mold material as described in the above aspect (17), which comprises the step of:
(19) The method for producing a mold material according to the aspect (17) or the aspect (18), wherein the water-soluble inorganic binder is water glass.
(20) The method for producing a mold material according to any one of the modes (17) to (19), wherein the liquid binder composition contains water.
(21) After the mold material according to any one of the above aspects (1) to (14) is filled in a mold, the mold material is held in the mold, and a) the mold is heated Accordingly, the mold material filled in the mold is solidified or cured by b) adding a curing agent into the mold or c) decompressing the inside of the mold. , A method of producing a mold characterized by obtaining a target mold.
(22) The method for producing a mold according to the above mode (21), wherein hot air or superheated steam is ventilated in the mold while holding the mold.
(23) The mode (21) or the mode (22), wherein a carrier gas consisting of at least one of carbon dioxide, argon, nitrogen, helium and air is allowed to flow into the mold while holding the mold. The method for producing a mold according to.
(24) The embodiment wherein the mold is heated to a temperature of 80 ° C. to 300 ° C.
21) The manufacturing method of the mold as described in any one of the said aspect (23).
(25) After casting is performed using a mold made of a solidified or hardened material of the mold material according to any one of the above-mentioned aspect (1) to the above-mentioned aspect (14), molding sand is cast from the mold A method of reclaiming foundry sand comprising recovering and subjecting to dry regeneration treatment to obtain reclaimed sand.

According to such a wet mold material according to the present invention, various effects as listed below can be exhibited.
(A) When casting is carried out using a mold consisting of a mold material in a wet state according to the present invention (hereinafter referred to simply as the mold in this paragraph), heat generated by molten metal causes the cast sand surface to The organic compounds contained in the solid coating layer are effectively pyrolyzed, whereby the disintegrability of the casted mold becomes good. Moreover, in the foundry sand recovered from the mold after casting, the solidified or hardened material of the water-soluble inorganic binder is easily exfoliated from the surface of the foundry sand by the thermal decomposition of the above-mentioned organic compound. Therefore, the recovered sand can be easily regenerated by subjecting it to a dry regeneration treatment having a polishing step and the like.
(B) At the time of casting using a mold, a gas is generated by the thermal decomposition of the organic compound contained in the coating layer, so that the gas prevents the molten metal from invading between particles (sand grains) of casting sand constituting the mold. Layers are advantageously formed between the mold surface and the cast product, resulting in a better cast surface of the final cast product.
(C) In the template material in the wet state according to the present invention, since the organic compound is present in solid form, the problem of odor due to volatilization of the organic compound is less likely to occur.
(D) In the wet mold material according to the present invention, when inorganic oxide particles or a moisture resistance improver is contained in the liquid caking agent composition, strength reduction in the moisture-absorbed mold is advantageously suppressed. Therefore, the moisture resistance of the mold can be improved.
(E) In the mold material of the present invention, when the coupling agent is contained in the solid coating layer and / or in the liquid binder composition, the wettability and the adhesion are improved, The bond between the foundry sand and the coating layer and / or the bond between the coating layer on the foundry sand surface and the water-soluble inorganic binder is
It becomes strong and can improve the strength of the mold.

It is longitudinal cross-sectional explanatory drawing of the sand mold for casting tests used by the disintegration test in an Example. BRIEF DESCRIPTION OF THE DRAWINGS It is longitudinal cross-section explanatory drawing of the aluminum alloy casting which included the waste core in the Example.

By the way, the mold material (coated sand) in the wet state according to the present invention is a cast sand coated with a solid coating layer containing an organic compound covered with a liquid caking agent composition containing a water-soluble inorganic caking agent It is what is done. Thus, in the mold material (coated sand) of the present invention, the foundry sand particles coated with the solid coating layer are covered with a liquid caking agent composition containing a water-soluble inorganic caking agent, From the point of being configured, it is in a wet state (appearance) as a whole, that is, it exhibits a wet state.

Here, in the present specification and claims, the mold material in a wet state (coated sand) means a mold material (coated sand) having no cold flowability. More specifically, a mold material (coated sand) for which a measured value can not be obtained when the dynamic repose angle is measured according to the following method is used as a wet mold material (coated sand). A dynamic repose angle is a mold material (coated sand) placed in a cylinder with one side transparent and a flat surface (for example, a mold material (coated diameter up to a half of a volume: 7.2 cm × height: 10 cm) Sand), rotating at a constant speed (for example, 25 rpm), the slope of the layer of mold material (coated sand) flowing in the cylinder becomes flat, and the angle formed between the slope and the horizontal surface It is measured. In such a measurement method, the mold material (coated sand) does not flow in the cylinder, the slope of the layer of the mold material (coated sand) is not formed as a flat surface, and therefore the dynamic repose angle can not be measured. The mold material (coated sand) of The wet mold material (coated sand) is superior to the dry mold material (coated sand) in that it is easy and inexpensive to manufacture.

First, as a foundry sand constituting a wet mold material according to the present invention, it is a refractory substance which functions as a mold base, and various kinds of refractory granules or powders conventionally used for molds. Materials such as silica sand, regenerated silica sand, alumina sand, olivine sand, zircon sand, chromite sand, special sand, ferrochrome-based slag, ferronickel-based slag, and Examples thereof include slag-based particles such as furnace slag; artificial particles such as alumina-based particles and mullite-based particles; and regenerated particles thereof; alumina balls and magnesia clinker. In addition, even if these casting sands are new sands or regenerated sands or recovered sands used one or more times for molding of molds, furthermore, such reclaimed sands or recovered sands Even if it is mixed sand which is made to add new sand to it and mix it, there is no difference at all. Such casting sand is generally used as one having a particle size of about 40 to 130 in the AFS index, and preferably having a particle size of about 60 to 110. The molding sand is preferably spherical, and specifically, it is desirable that the grain shape factor is 1.2 or less, more preferably 1.0 to 1.1. By using the casting sand having a grain shape factor of 1.2 or less, the flowability and the filling property at the time of mold production are improved, and the same strength is expressed because the number of contacts between casting sand materials is increased. Therefore, the amount of caking agent and the amount of additives required for the preparation can be reduced. In addition, the grain shape factor of the foundry sand used here is generally adopted as one measure indicating the outer shape of the particle, and is also referred to as a grain shape index, and as the value approaches 1 the spherical shape It is meant to approach (true sphere). And such a particle shape factor is represented by a value calculated using the surface area (sand surface area) of the foundry sand measured by various known methods, for example, a sand surface area measuring instrument ( The surface area of an actual foundry sand particle (sand grain) per 1 g is measured using George Fisher, and the value is obtained by dividing it by the theoretical surface area. The theoretical surface area is the surface area under the assumption that casting sand particles (sand particles) are all spherical.

Moreover, the molding sand which comprises the casting_mold | template material of this invention is that in which the solid-like coating layer containing the organic compound is coat | covered the surface. As described above, the presence of the predetermined coating layer on the surface of the casting sand prevents the water-soluble inorganic binder described later from being in direct contact with the casting sand. Further, since the solid coating layer contains an organic compound, when molten metal is poured into a mold (hereinafter, simply referred to as a mold) formed using the template material of the present invention, the organic substance contained in the coating layer The compound is pyrolyzed and gasified, and the generated gas advantageously destroys the solidified or hardened substance of the water-soluble inorganic binder at the joint between the sand particles, and the mold disintegrates It will be excellent. Furthermore, when the organic compound contained in the coating layer is pyrolyzed and gasified, the solidified or hardened product of the water-soluble inorganic binder present on the casting sand particles is generated from the inside by the internal pressure of the gas. For example, since it is broken from the sand particle side, the solidified or hardened water-soluble inorganic binder is exfoliated from the surface of the foundry sand particle in the polishing step for regenerating the foundry sand recovered from the mold after casting. It becomes easy and the reproduction of casting sand becomes easy. In addition, since a gas is generated by thermal decomposition of the organic compound contained in the coating layer during casting using a mold, a gas layer that inhibits molten metal from invading between casting sand particles constituting the mold is It is advantageously formed between the mold surface and the cast product, so that the cast surface of the cast product finally obtained is improved.

In the present invention, the film thickness of the solid coating layer formed on the casting sand surface is 0.1 to 6 μm, preferably 0.2 to 5 μm, more preferably 0.3 to 3 μm, still more preferably 0.5. It is set to 2 μm. If the film thickness is less than 0.1 μm, it may be difficult to form as a coating layer, and it may be difficult to gasify inside the layer composed of a binder composition containing a water-soluble inorganic binder. On the other hand, if it is thicker than 6 μm, there is a risk that an organic compound may generate an odor. In addition, as a measuring method of the film thickness of a coating layer, the casting sand particle in which the coating layer was formed is embedded in an epoxy resin etc., The cross section of the casting sand particle which cut using cutting devices, such as an ion cutter, The observation can be carried out using an optical machine such as an electron microscope, 10 cross-sectional particles can be randomly selected, and the film thickness of the coating layer can be measured. Moreover, regarding a film thickness, when a foundry sand particle is spherical, you may calculate from the average particle diameter of a foundry sand particle, and the addition amount of a foundry sand particle and an organic compound.

Further, the organic compound used in the present invention can be contained in a solid coating layer as well as those capable of forming a solid coating layer on the surface of casting sand particles. If it is present, it is not particularly limited, but it is preferably at least one selected from the group consisting of a cross-linking curable resin and its cured product, a thermoplastic resin, and a carbohydrate.

The crosslinking curing resin is, for example, heating or non-heating in the presence or absence of a curing agent such as hexamethylenetetramine, organic ester, organic acid, carbon dioxide, peroxide, metal ion, amine or curing catalyst (normal temperature (normal temperature) Under these conditions, crosslinking hardenability is developed, and foundry sand particles are mutually attached to form a mold. As such a crosslinkable curable resin, specifically, a phenol resin, a phenol urethane resin, an epoxy resin, a melamine resin, an unsaturated polyester resin, a polyfunctional acrylamide resin (refer to Japanese Patent Publication No. 7-106421) And unsaturated alkyd resins, unsaturated fatty acid modified alkyd resins, diallyl phthalate resins, and resins obtained by combining these resins as required. Among these, from the viewpoint of achieving the effects of the present invention more advantageously, particularly preferred are phenolic resins of novolac type and resol type, and phenolic urethane resins used by mixing with polyisocyanate compounds.

Further, the cured product of the crosslinkable curable resin is one obtained by increasing the molecular weight of a low molecular weight compound to a polymer compound by curing reaction. After coating the surface of the foundry sand particles with a low molecular weight material with low melt viscosity, hardening by heating or addition of a curing agent prevents alkaline deterioration and has a high molecular weight with good surface stability. A coating layer can be formed, and coexistence of coating property and surface stability is possible. In addition, in the cured product of the crosslinkable curable resin, 1) softening of the coating layer due to heat is suppressed and the mold strength is improved, and 2) it is necessary for curing in advance, as compared with the uncured crosslinkable curable resin. Because heat is consumed, heat is effectively used for thermal decomposition and thermal decomposition is accelerated, so that the mold disintegrability is further improved and, furthermore, 3) the gas associated with curing is released in advance. There is also an advantage that the amount of gas generated during casting can be reduced.

Further, as the thermoplastic resin, specifically, polyvinyl alcohol, polyvinyl acetate, polystyrene, styrene acrylonitrile copolymer, styrene butadiene acrylonitrile copolymer, ethylene vinyl acetate copolymer, polymethyl methacrylate, methacryl methacrylate Styrene copolymer, cellulose acetate, polycarbonate, resin comprising polyvinyl chloride and the like can be mentioned. Among them, polyvinyl alcohol, polyvinyl acetate, polystyrene, ethylene vinyl acetate copolymer, polymethyl methacrylate, cellulose acetate, and polycarbonate are particularly preferable from the viewpoint of solvent solubility (film forming property).

Furthermore, specific examples of the carbohydrate include those composed of glucose, fructose, galactose, lactose, sucrose, maltose, trehalose, starch, glycogen, cellulose and the like. Among them, trehalose, starch and glycogen are particularly preferable from the viewpoint of film formability. In addition, as other organic compounds, acrylamide, N-methylol acrylamide, diacrylamidodimethyl ether, methylene bis acrylamide, ethylene bis acrylamide, ethylene glycol diacrylamide and the like can be mentioned.

In the present invention, the organic compound contained in the coating layer on the surface of the casting sand is preferably a polymer compound (polymer, polymer) from the viewpoint of the covering property to the casting sand particles. Specifically, a polymer compound (polymer, multimer) having a weight average molecular weight of 300 or more, preferably 300 to 100,000,000, more preferably 500 to 50,000,000, and still more preferably 800 to 20,000,000 is advantageously used. Even organic compounds not included in the category of polymer compounds (polymers and polymers) are preferably those having a molecular weight of 300 or more from the viewpoint of surface stability of a solid coating layer, and it is preferable to From the viewpoint of the coatability of the (1), those of 100,000,000 or less are preferable.

In the present invention, a poorly water-soluble or water-insoluble organic compound is advantageously used, and a water-insoluble organic compound is particularly preferable as the organic compound contained in the solid coating layer. The reason is that when a water-soluble organic compound is used, it dissolves in the water contained in the liquid binder composition containing the water-soluble inorganic compound coated on the surface of the coating layer, and is solid This is because there is a risk that the coating layer can not be maintained. Specifically, in the present invention, the solubility in 100 g of water at 25 ° C. is 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.3% by mass or less, still more preferably 0.1% by mass The organic compound which is the following is used as an organic compound contained in a solid coating layer. The solubility means the amount of the organic compound dissolved in the solvent (water) when 100 g of water at 25 ° C. is charged with 10 g of the organic compound, stirred for 1 hour, and allowed to stand still for 1 hour. It is a thing. Further, the water-insoluble organic compound is an organic compound which does not dissolve in water.

Furthermore, in the wet mold material according to the present invention, a coupling agent may be contained in the coating layer provided on the surface of the molding sand. By including a coupling agent in such a coating layer, the wettability and adhesion of the coating layer can be improved, and the bond between the molding sand and the coating layer can be strengthened. As a coupling agent contained in a coating layer, a silane coupling agent, a zircon coupling agent, a titanium coupling agent etc. can be mentioned as a suitable thing, for example. The content of the coupling agent in the coating layer is generally 0.5 to 10 parts by mass, preferably 1 to 5 parts by mass, more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the organic compound. The ratio of

On the other hand, in the wet mold material according to the present invention, casting sand coated with the above-mentioned predetermined coating layer is coated with a liquid caking agent composition containing a water-soluble inorganic caking agent. . Any water-soluble inorganic binder contained in the liquid binder composition can be used as long as it is conventionally used in a template material (coated sand). Such water-soluble inorganic binders include, for example, water glass, sodium chloride, sodium phosphate, sodium carbonate, sodium vanadate, sodium borate, sodium aluminum oxide, potassium chloride, potassium carbonate and the like, and What has 2 or more types chosen from them as a main component etc. can be mentioned. Among them, water glass and water glass as a main component are preferable from the viewpoint of easy handling and the finally obtained mold strength. Here, water glass is an aqueous solution of a soluble silicate compound, and as such a silicate compound, for example, sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, lithium silicate, Although ammonium silicate etc. can be mentioned, sodium silicate (sodium silicate) will be used advantageously in the present invention. In addition, water glass may be used as the main component, and other water-soluble caking agents such as thermosetting resins, saccharides, proteins, synthetic polymers, salts and inorganic polymers may be blended. When water glass and another water-soluble binder are used in combination, the proportion of water glass in the total amount of the binder is 60% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more.

Moreover, although the water soluble inorganic caking agent mentioned above has a solid thing and a liquid thing as a form handled normally, a solid thing is used in the state of aqueous solution. And, advantageously, the viscosity of the liquid caking agent composition containing the water-soluble inorganic caking agent is adjusted to 5 to 2000 cP, preferably 7 to 1200 cP, more preferably 7 to 800 cP at 25 ° C. Be done. In such preparation, even if it is a liquid water-soluble inorganic binder such as water glass, it is possible to use one diluted with water in order to adjust the viscosity of the binder composition. In addition, it is also possible to separately add a solid or liquid water-soluble inorganic binder and water to the fireproof aggregate or the like at the time of kneading or mixing with foundry sand.

Here, sodium silicate, which is advantageously used in the present invention, is generally classified into the types 1 to 5 according to the molar ratio SiO ₂ / Na ₂ O. Being used. Specifically, sodium silicate No. 1 has a SiO ₂ / Na ₂ O molar ratio of 2.0 to 2.3, and sodium silicate No. 2 has SiO ₂ / Na ₂ O ₂ The molar ratio is 2.4 to 2.6, and sodium silicate No. 3 is the one having a molar ratio of SiO ₂ / Na ₂ O of 2.8 to 3.3. In addition, sodium silicate No. 4 has a SiO ₂ / Na ₂ O molar ratio of 3.3 to 3.5, and sodium silicate No. 5 has a SiO ₂ / Na ₂ O molar ratio Is 3.6 to 3.8. Among these, sodium silicate Nos. 1 to 3 are also defined in JIS-K-1408. Then, sodium These silicate, other uses alone may be used as a mixture, also by mixing more than two kinds, preparing a molar ratio of SiO ₂ / Na ₂ O Is also possible.

Incidentally, to obtain advantageously the mold material Shimetai according to the present invention, the sodium silicate which constitutes the water glass used as a binder, the molar ratio of SiO ₂ / Na ₂ O, generally 1.9 or more, Preferably, it is preferably 2.0 or more, more preferably 2.1 or more, and in the above-mentioned classification of sodium silicate, sodium silicate corresponding to No. 1 and No. 2 is particularly advantageously used. . Such sodium silicates No. 1 and No. 2 are stable and provide a mold material having good properties even in a wide range of sodium silicate concentration in water glass. In addition, the upper limit of the molar ratio of SiO ₂ / Na ₂ O in such sodium silicate is appropriately selected according to the characteristics of water glass in the form of an aqueous solution, but generally not more than 3.5, It is preferably 3.2 or less, more preferably 2.7 or less. Here, when the molar ratio of SiO ₂ / Na ₂ O is smaller than 1.9, a large amount of alkali is present in the water glass, so the solubility of the water glass in the water increases, and the template material absorbs moisture and deteriorates. There is a risk that it will be easier to do. On the other hand, with sodium silicate having a SiO ₂ / Na ₂ O molar ratio of greater than 3.5, the solubility in water is low, so that the bonding area between foundry sand particles can not be obtained in the mold finally obtained. There is a risk that the mold strength may be reduced.

In addition, the water glass used in the present invention means a solution of a silicate compound in a state of being dissolved in water, and when producing the template material of the present invention, it is in the state of a stock solution as purchased in the market. Besides being used, water is added to such a stock solution to be used in a diluted state. And the non volatile matter (water glass component) except the volatilizable substance such as water and solvent from such water glass is referred to as solid content, and this corresponds to the soluble silicate compound such as sodium silicate described above It is a thing. Moreover, the higher the proportion of such solid content, the higher the concentration of the silicate compound in the water glass. Therefore, the solid content of water glass used in the present invention corresponds to the ratio excluding the amount of water in the stock solution when it is composed only of the stock solution, while the stock solution is water. When a diluted solution obtained by dilution is used, the ratio excluding the amount of water in the stock solution and the amount of water used for dilution corresponds to the solid content of the water glass used It becomes.

In the present invention, sodium chloride (NaCl), which can be used as a water-soluble inorganic binder, is edible as said to be common salt, is harmless to the human body, and can be used inexpensively and easily. It is possible. In addition, since it is easily dissolved in water, a mold material using sodium chloride as a binder can produce a mold that is easily disintegrated by water. The amount of sodium chloride dissolved in 100 g of water is 35.9 g (20 ° C.). Furthermore, since the melting point of sodium chloride is 1413 ° C. and is relatively high, a mold having high heat resistance can be produced.

Moreover, as sodium phosphate, monosodium phosphate hydrate (NaH ₂ PO ₄ .xH ₂ O; x is a known integer), disodium phosphate hydrate (Na ₂ HPO ₄ .x'H ₂ O) X 'is a known integer, trisodium phosphate hydrate (Na ₃ PO ₄ .x "H ₂ O; x" is a known integer) or the like. And sodium phosphate is soluble in water as represented by that the dissolution amount of trisodium phosphate hydrate in 100 g of water is 25.8 g (20 ° C.), and disodium phosphate water The melting point of sodium phosphate is relatively high, as typified by the melting point of the solvate being 1340 ° C. For this reason, the template material using sodium phosphate as a water-soluble inorganic binder can be easily disintegrated with water, and a template having high heat resistance can be manufactured.

Furthermore, sodium carbonate (Na ₂ CO ₃ ) has a dissolved amount of 17.4 g (20 ° C.) in 100 g of water, is easily dissolved in water, and is inexpensive. Also, the melting point is relatively high at 851 ° C. For this reason, the mold material using sodium carbonate as a water-soluble inorganic binder can be easily disintegrated with water, and a mold having high heat resistance can be manufactured.

In addition, sodium vanadate (Na ₃ VO ₄ ) is soluble in water and has a relatively high melting point of 866 ° C. For this reason, the template material using sodium vanadate as a water-soluble inorganic binder can be easily disintegrated with water, and a template having high heat resistance can be produced.

Furthermore, sodium aluminum oxide (NaAlO ₂ ) is soluble in water, and has a melting point as high as 1700 ° C. or higher. For this reason, the mold material using sodium aluminum oxide as a water-soluble inorganic binder can be easily disintegrated with water, and a mold having high heat resistance can be produced.

In addition, potassium chloride (KCl) is easy to dissolve in water and is inexpensive, as the amount dissolved in 100 g of water is 34.2 g (20 ° C.). Also, the melting point is relatively high at 776 ° C. For this reason, the template material using potassium chloride as a water-soluble inorganic binder easily disintegrates with water, and it is possible to produce a template having high heat resistance.

Potassium carbonate (K ₂ CO ₃ ) is easily dissolved in water so that the amount dissolved in 100 g of water is 111.9 g (20 ° C.), and the melting point is 891 ° C., which is relatively high. For this reason, the mold material using potassium carbonate as a water-soluble inorganic binder can be easily disintegrated with water, and a mold having high heat resistance can be produced.

And the content rate in the liquid caking agent composition of such a water soluble inorganic caking agent will be made into a suitable rate according to the kind etc. of the water soluble inorganic caking agent used. The solid content of the water-soluble inorganic binder is advantageously 10 to 80% by mass, preferably 15 to 70% by mass, more preferably 20 to 50%, from the viewpoint of molding speed and strength of the finally obtained mold. It is desirable to be contained in a liquid caking agent composition in a proportion by mass. By using a liquid binder composition containing the solid content of the water-soluble inorganic binder in such a proportion, such a casting when mixed (kneaded) with foundry sand particles having a predetermined solid coating layer The sand particles can be coated uniformly and uniformly with the water-soluble inorganic binder component, which makes it possible to advantageously mold the target mold according to the invention. . In addition, the concentration of the water-soluble inorganic caking agent component (solid content) in the liquid caking agent composition is too low, specifically, a liquid caking agent having a solid content of less than 10% by mass. When the composition is used, it is necessary to raise the heating temperature or to prolong the heating time for drying of the mold material during molding, which causes problems such as energy loss. Become. On the other hand, when a liquid caking agent composition having too high a solid content ratio is used, it becomes difficult to uniformly coat the surface of the foundry sand particles with the caking agent composition, and the characteristic problem in the mold Since there is a risk of causing the problem, the liquid content is such that the solid content is 80% by mass or less, so that the solvent such as water is 20% by mass or more (the water content is 10% by mass or more). It is desirable to prepare a binder composition.

The water-soluble inorganic binder is considered to be only the mass in the case of solid and the solid content in the case of liquid in 100 parts by mass of casting sand in the wet mold material according to the present invention. It is used in a proportion of 0.1 to 5 parts by mass, preferably 0.2 to 2.5 parts by mass, more preferably 0.5 to 2.0 parts by mass in terms of solid content desirable. By using a water-soluble inorganic binder in such a quantitative ratio, the surface of the solid coating layer provided on the surface of the foundry sand particles is a liquid caking agent containing a water-soluble inorganic binder. The wet mold material of the present invention coated with the composition is advantageously configured. In addition, the measurement of solid content is implemented as follows. That is, 10 g of the sample is accommodated in an aluminum foil sample plate (length: 9 cm, width: 9 cm, height: 1.5 cm), weighed, and placed on a heating plate maintained at 180 ± 1 ° C. After standing for a minute, the sample pan is inverted and left on the heating plate for a further 20 minutes. Then, the sample plate is taken out from the heating plate, allowed to cool in a desiccator, and weighed, and the solid content (% by mass) is calculated by the following equation.
Solid content (mass%)
= {[Mass of sample pan after drying (g)-mass of sample pan (g)]
/ [Mass of sample pan (g) before drying-mass of sample pan (g)] × 100

In the present invention, when the amount of the water-soluble inorganic binder used is too small, a sufficient amount of the water-soluble inorganic binder does not exist on the solid coating layer provided on the surface of the casting sand, There is a risk that the mold material may not be sufficiently solidified or cured. In addition, even if the amount of the water-soluble inorganic binder used is too large, an excessive amount of the water-soluble inorganic binder is present on the solid coating layer provided on the surface of the casting sand. Foundry sand particles may stick to each other to form agglomerates (composite particle formation), which adversely affects mold physical properties and also makes it difficult to remove core sand after metal casting. It comes to evoke.

Here, in the mold material according to the present invention, it is possible to include a coupling agent in the liquid binder composition containing the water-soluble inorganic binder as described above. By incorporating a coupling agent into the caking agent composition, the wettability and the adhesion are improved, and the bond between the coating layer on the surface of the casting sand and the water-soluble inorganic caking agent can be strengthened. Such effects can be achieved by incorporating the coupling agent in either the coating layer or the binder composition, but both the coating layer and the binder composition are coupled. By including the agent, the bonding strength between the two is further improved, and the strength is further improved in the finally obtained template, which is further preferable. As a coupling agent contained in a liquid caking agent composition, what was previously listed as a coupling agent which can be contained in a coating layer can be illustrated. The content of the coupling agent in the liquid caking agent composition is generally 0.5 to 10 parts by mass, preferably 100 parts by mass of the solid content of the water-soluble inorganic caking agent contained therein. The proportion is 1 to 5 parts by mass, more preferably 1 to 3 parts by mass.

In addition, the liquid binder composition containing a water-soluble inorganic compound may contain inorganic oxide particles. The inclusion of the inorganic oxide particles in the binder composition is effective in improving the flowability and filling properties of the mold material, and the moisture resistance of the finally obtained mold. The size of the inorganic oxide particles used in the present invention is preferably smaller than the casting sand particles that together constitute the template material, and specifically, the average particle diameter is preferably 0.01 μm to 300 μm, more preferably Inorganic oxide particles having a diameter of 0.3 μm to 200 μm, particularly preferably 0.5 μm to 100 μm, are used. The average particle diameter can be determined from a particle size distribution measured by a laser diffraction type particle size distribution measuring apparatus or the like. The content of the inorganic oxide particles in the binder composition is generally 5 to 200 parts by mass, preferably 10 to 100 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble inorganic binder contained therein. It is considered as a proportion of parts by mass.

In addition, although the inorganic oxide particles used in the present invention may be spherical particles or non-spherical particles, spherical particles are more advantageous in exhibiting the effects of the present invention, and in particular, they have a better cast surface. It is preferable in that it is possible to obtain a cast product having the same. And such a spherical particle should just show the spherical shape of generally recognized degree, and although it is not necessarily required to show a spherical shape, Usually, sphericity is 0.5 or more , Preferably 0.7 or more, more preferably 0.9 or more, is advantageously used. Here, in the observation using a scanning electron microscope, the sphericity is randomly selected from 10 single particles, and the aspect ratio (ratio of the minor axis / major axis) obtained from the projection shape is It means an average value. In the case where inorganic oxide particles that are not spherical are used, protrusions and depressions are present on the surface of the inorganic oxide particles, so that, for example, the inorganic oxide particles form a solution by the supplied water. If it tries to flow between casting sand particles together with the water glass, the projections on the surface of the inorganic oxide particles collide with the casting sand particles and other inorganic oxide particles, etc., resulting in an anti-slip effect, resulting in casting sand The flow of the water glass and the inorganic oxide particles between the particles is impeded, and as a result, the fillability of the finally obtained mold and the strength thereof may be reduced.

Further, the material constituting such inorganic oxide particles is not particularly limited, but an inorganic metal oxide is preferable. As particles consisting of inorganic metal oxides, particles consisting of silicon dioxide, aluminum oxide, titanium oxide etc. are advantageously used, and among them, in particular, silicon dioxide particles are such that strongly alkaline water glass is silicon dioxide. It can react with silanol groups formed on the surface, and upon evaporation of water, a strong bond can be formed between silicon dioxide and solid water glass to improve mold strength. Is preferred. Silicon dioxide is crystalline or amorphous, but amorphous is more preferable. As amorphous silicon dioxide, precipitated silica, pyrogenic silica formed in an electric arc or by flame hydrolysis, ZrSiO Examples include silica produced by the thermal decomposition of ₄ , silicon dioxide produced by oxidation of metallic silicon with a gas containing oxygen, quartz glass powder of spherical particles produced from crystalline quartz by melting and subsequent quenching, etc. . These can be used alone or in combination of two or more. In the present invention, silicon dioxide is treated as an inorganic metal oxide.

Furthermore, a moisture resistance improver may be contained in the liquid caking agent composition constituting the present invention. By incorporating a moisture resistance improver in the binder composition, the moisture resistance of the finally obtained mold can be improved. As the moisture resistance improver used in the present invention, any agent can be used as long as it does not inhibit the effects of the present invention as long as it is conventionally used in a mold material. Specifically, zinc carbonate, basic zinc carbonate, iron carbonate, manganese carbonate, copper carbonate, aluminum carbonate, barium carbonate, magnesium carbonate, calcium carbonate, lithium carbonate, potassium carbonate, carbonates such as sodium carbonate, tetraboric acid Sodium, potassium tetraborate, lithium tetraborate, ammonium tetraborate, calcium tetraborate, strontium tetraborate, silver tetraborate, sodium metaborate, potassium metaborate, lithium metaborate, ammonium metaborate, metaborate Calcium, silver metaborate Copper metaborate, lead metaborate, magnesium metaborate and other borates, sodium sulfate, potassium sulfate, lithium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, titanium sulfate, aluminum sulfate, sulfate Zinc, copper sulfate Sulfate, sodium phosphate, sodium hydrogen phosphate, potassium phosphate, potassium hydrogen phosphate, lithium phosphate, lithium hydrogen phosphate, magnesium hydrogen phosphate, calcium phosphate, calcium phosphate, titanium phosphate, aluminum phosphate, zinc phosphate etc. Phosphate, lithium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, aluminum hydroxide, hydroxides such as zinc hydroxide, silicon, zinc, magnesium, aluminum, calcium, lithium, copper Examples of such oxides include iron, boron, and zirconium. Among them, particularly basic zinc carbonate, sodium tetraborate, potassium metaborate, lithium sulfate and lithium hydroxide improve moisture resistance more advantageously when water glass is used as a water-soluble inorganic binder. It is possible. The moisture resistance improver including those described above may be used alone or in combination of two or more. In addition, although the compound which can be used as a water-soluble inorganic caking agent is also contained in the moisture resistance improving agent listed previously, in such a compound, the water-soluble inorganic caking agent different from it is mentioned When used, it can act as a moisture resistance improver.

The amount of such a moisture resistance improver used is generally 0.5 to 10 parts by mass of the solid content of the water-soluble inorganic binder in the liquid caking agent composition in the total amount. The amount is preferably about 50 parts by mass, more preferably 1 to 20 parts by mass, and particularly preferably 2 to 15 parts by mass. In order to advantageously enjoy the addition effect of the moisture resistance improver, it is desirable that the use amount be 0.5 parts by mass or more, and on the other hand, if the addition amount is too large, the binding of the water-soluble inorganic caking agent It is desirable that the amount be 50 parts by mass or less, because it may cause problems such as the strength of the finally obtained template being reduced.

Furthermore, in the mold material according to the present invention, a surfactant may be contained in the liquid binder composition covering the surface of the foundry sand particles. Due to the fact that the surfactant is contained in the binder composition containing the water-soluble inorganic binder, the wet mold material according to the present invention is prepared 1) in the presence of the surfactant. Allowing the amount of water added during the process to be minimized, and 2) the surface tension of water is suppressed, the flowability of the mold material is improved, and 3) the mold is formed In addition to the fact that the mold is excellent in the releasability from the mold, effects such as exhibiting excellent strength can be advantageously enjoyed. In the present invention, the content of the surfactant in the liquid caking agent composition is 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble inorganic caking agent contained therein. It is preferably part, particularly preferably 0.5 to 15.0 parts by mass, and particularly preferably 0.75 to 12.5 parts by mass.

In the present invention, as the surfactant added to the liquid caking agent composition, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, a silicone-based interface Both activators and fluorosurfactants can be used. Specifically, as the cationic surfactant, aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts and the like can be mentioned. Further, as anionic surfactants, fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-N-methyl-β-alanine salt, N-acyl glutamate, alkyl ether carboxylate, acyl Peptide, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfo borate, alkyl sulfo acetate, α-olefin sulfonate, N-acyl methyl taurine, sulfated oil, higher alcohol Sulfate ester, secondary higher alcohol sulfate, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate, polyoxyethylene alkyl phenyl ether sulfate, monoglysulfate, fatty acid alkylol amide sulfate, alkyl ether phosphorus Acid A stell salt, an alkyl phosphate ester salt etc. are mentioned. Furthermore, as the amphoteric surfactant, carboxybetaine type, sulfobetaine type, amino carboxylate, imidazolinium betaine and the like can be mentioned. In addition, as nonionic surfactants, polyoxyethylene alkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkyl phenyl ether (for example, Emulgen 911), polyoxyethylene sterol ether, polyoxyethylene lanolin derivative , Polyoxyethylene polyoxypropylene alkyl ether (eg, Neupol PE-62), polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, Polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fat Esters, sucrose fatty acid esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amines, alkyl amine oxides, acetylene glycol, acetylene alcohol, and the like.

Further, among various surfactants, in particular, those having a siloxane structure as a nonpolar site are called silicone surfactants, and those having a perfluoroalkyl group are called fluorosurfactants. Examples of silicone surfactants include polyester-modified silicone, acrylic-terminated polyester-modified silicone, polyether-modified silicone, acrylic-terminated polyether-modified silicone, polyglycerin-modified silicone, aminopropyl-modified silicone and the like. Moreover, as a fluorochemical surfactant, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl group Included oligomers and the like.

In the present invention, various surfactants as described above can be used alone or in combination of two or more. However, some surfactants react with the water-soluble inorganic binder, and there is a possibility that the surface activity decreases or disappears with the passage of time, so, for example, water glass as the water-soluble inorganic binder Such anionic surfactants which do not react with water glass, nonionic surfactants and silicone surfactants are particularly advantageously used in the template material of the present invention.

In addition, in the wet mold material according to the present invention, a polyhydric alcohol may be contained in the liquid binder composition covering the surface of the foundry sand particle on which the coating layer is formed. As described above, since the polyhydric alcohol is contained in the binder composition containing the water-soluble inorganic binder, the swelling property of the mold material in the wet state during heating of the mold is heated. It can be stably maintained until solidified or cured. In the present invention, the content of polyhydric alcohol in the binder composition is 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble inorganic binder contained therein. Among them, 0.5 to 15.0 parts by mass is more preferable, and 0.75 to 12.5 parts by mass is most preferable.

Specific examples of polyhydric alcohols that can be used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, dipropylene glycol, propylene glycol, butylene glycol, and 1,2-butanediol. 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 2-ethyl-1,3-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 1,2- Octanediol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane and the like can be exemplified.

Furthermore, in the wet-type mold material according to the present invention, various kinds of publicly known additives may be used alone or together with the above-mentioned coupling agent or the like in the liquid caking agent composition covering the periphery of casting sand particles. It is also possible to optionally contain additives. Incidentally, in order to incorporate such an additive into the binder composition, when a liquid binder composition is prepared, it is added to the composition together with a water-soluble inorganic binder etc. A method of mixing or mixing a caking agent composition containing an additive with a foundry sand, or adding a predetermined additive to the foundry sand separately from the caking agent composition A method of uniformly kneading or mixing is adopted.

As one of such additives, in the present invention, a lubricant which contributes to the improvement of the flowability of the mold material is advantageously used. Examples of lubricants usable in the present invention include waxes such as paraffin wax, synthetic polyethylene wax and montanic acid wax; fatty acid amides such as stearic acid amide, oleic acid amide and erucic acid amide; methylenebisstearic acid amide and ethylene bis Alkylene fatty acid amides such as stearic acid amide; stearic acid, stearyl alcohol; lead stearate, zinc stearate, calcium stearate, metal stearate such as magnesium stearate; stearic acid monoglyceride, stearyl stearate, hydrogenated oil etc. You can do it. Further, as a mold release agent, paraffin, wax, light oil, machine oil, spindle oil, insulating oil, waste oil, vegetable oil, fatty acid ester, organic acid, graphite fine particles, mica, vermiculite, fluorine-based mold release agent, silicone-based mold release Agents and the like can also be used. These other additives are generally 0.5 to 10 parts by mass, preferably 1 to 100 parts by mass of the solid content of the water-soluble inorganic binder contained in the liquid caking agent composition. It is contained in a proportion of ̃5 parts by mass, more preferably 1 to 3 parts by mass.

By the way, the mold material in a wet state according to the present invention is 1) first, after forming a solid coating layer containing an organic compound on the surface of casting sand, 2) for casting sand on which such a coating layer is formed. It is possible to produce advantageously by adding and kneading or mixing a liquid caking agent composition containing a water-soluble inorganic caking agent.

In producing the wet mold material of the present invention according to such a production method, first, as a method of forming a solid coating layer containing an organic compound on the surface of casting sand, among various known methods, From the above, ones according to the characteristics and the like of the organic compound are appropriately selected and adopted. For example, as a method of forming a solid coating layer containing an organic compound on the surface of casting sand, a dry hot coating method, a cold coating method and the like can be exemplified, but a solid coating layer can be formed. If there is, the method is not particularly limited.

In the dry hot coating method, solid organic compounds are added to and mixed with foundry sand heated to 130 to 180 ° C., and solid organic compounds are melted by the heat of the foundry sand, and the melted organics This is a method of forming a solid coating layer on the surface of casting sand by coating the surface of the refractory aggregate with a compound and then cooling while maintaining this mixture. In the cold coating method, the organic compound is dissolved as it is or in a solvent such as methanol to make a liquid, the liquid is added to casting sand and mixed, and the solvent is volatilized, etc. Is a method of forming a solid coating layer.

Moreover, when using a crosslinking curable resin as the organic compound, for example, after forming a solid coating layer according to the coating method described above, by further heating, and / or by adding a curing agent or a curing catalyst, The crosslinkable curable resin may be cured to increase the molecular weight of the crosslinkable curable resin contained in the coating layer. In the case of curing the crosslink-curable resin by heating, for example, it is placed in a thermostatic bath of 120 ° C. to 300 ° C. and reaction hardened for about 5 to 60 minutes, or casting sand is heated to 150 ° C. to 300 ° C., 120 ° C. There is a method of kneading for 5 to 60 minutes with a kneader heated to 300 ° C. for reaction hardening. In addition, since the mold material in which the crosslink-curable resin contained in the coating layer is cured has a strong neck between casting sand particles (sand particles), there is a possibility of forming an integrated block or forming composite particles, so the coating layer In order to improve the surface condition of the casting sand coated with the above, it is preferable to carry out reaction hardening with a quick kneader (speed muller) which has kneading and has a high rotational speed. Further, if kneading is performed for a long time, peeling may occur and fine powder may be generated. Therefore, it is preferable to react at high temperature for a short time. On the other hand, in the case of curing the crosslinkable curable resin using a curing agent or curing catalyst, for example, hexamethylenetetramine, organic ester, organic acid, carbon dioxide gas, peroxide, metal ion, etc. as the curing agent or curing catalyst. An amine or the like is used. In addition, when the crosslinkable curing resin is a phenol urethane resin, it is also possible to cure by mixing a phenol resin and a polyisocyanate resin. Even in the case of curing the crosslink-curable resin using a curing agent, it is desirable to carry out reaction curing while kneading with a kneader.

Then, when a casting sand provided with a solid coating layer containing an organic compound on its surface is coated with a liquid caking agent composition containing a water-soluble inorganic caking agent, for example, the coating layer is A solid containing an organic compound by kneading or mixing a water-soluble inorganic caking agent in the form of an aqueous solution as a caking agent, if necessary, with additives to the foundry sand, and uniformly mixing it. A wet mold material according to the present invention is obtained, which consists of a mixture of foundry sand provided with the following coating layer and a liquid binder composition containing a water-soluble inorganic binder. The various conditions for mixing are appropriately determined according to the type and water content of the water-soluble inorganic binder in the form of an aqueous solution, and the temperature for mixing is generally room temperature to 40 ° C. It is said that In the production of a moist mold material according to the present invention, the water content thereof is adjusted so that the obtained mold material exhibits an appropriate wet state, but, for example, as a water-soluble inorganic caking agent When water glass is used, the water content in the mold material is preferably 70 to 900% by mass, more preferably 95 to 500% by mass so as to be more than 55% by mass of the solid content of waterglass Adjusted to In the wet mold material according to the present invention, the moisture content of which is thus adjusted, the mold air in the wet state is dried and blocked by blow air at the time of filling the mold at the time of mold making. In addition to being able to prevent and maintain the wettability of the wet mold material, excellent properties are also imparted to molds molded using such mold material . The water content of the mold material can be measured by the weight change when heated by the Karl Fischer method, a drier or the like.

When molding the target mold using the wet mold material (coated sand) according to the present invention thus obtained, various conventionally known methods can be employed. For example, the above-mentioned wet mold material (coated sand) is loaded into the mold cavity of the mold which gives the desired mold, while such mold is brought to a temperature of 80-300.degree. C., preferably 100-200.degree. Heat and hold in the mold until the filled mold material (coated sand) is dry. By such heating and holding in the mold, solidification or curing of the filled mold material (coated sand) proceeds.

That is, by filling and holding a wet mold material (coated sand) in the cavity of the heated mold, molding sand particles constituting the mold material are added to the binder composition present in the periphery. Assemblages (bindings) of template materials are formed which are linked and linked to each other through the water-soluble inorganic binder contained, and exhibit an integral template shape. At this time, a curing agent may be added into the cavity as an additive for promoting the curing of the water-soluble inorganic binder. The water-soluble inorganic binder usually solidifies by evaporation of water if no additive is added, and hardens when a curing agent is added. is there. In the present invention, the mold consisting of an aggregate (binding body) of the mold material may be any of a mold material (coated sand) simply solidified (solidified material) and a hardened material (hardened material) by a curing agent. It is included.

In addition, as a curing agent, organic acids such as carbon dioxide (carbonated water), sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, oxalic acid, carboxylic acid, para-toluenesulfonic acid, methyl formate, ethyl formate, propyl formate, γ- Examples include esters of butyrolactone, γ-propion lactone, ethylene glycol diacetate, diethylene glycol diacetate, glycerin diacetate, triacetin, propylene carbonate, etc., and monohydric alcohols such as methanol, ethanol, butanol, hexanol, octanol, etc. Can do. These curing agents can be used alone or in combination of two or more.

Further, when heating the mold material in a wet state (coated sand) in the cavity of the mold, it is advantageous to heat the mold in a state of being preheated to a predetermined temperature (preheated) and kept warm at that temperature. It is preferred to prepare and fill the mold material into the cavity of such mold and to heat the mold material. Thus, by heating the mold in advance, it is possible to accelerate the drying of the mold material and shorten the molding time. As the temperature for keeping warm by this preheating, 80 to 300 ° C., preferably 100 to 200 ° C., more preferably 120 to 180 ° C. is employed. The temperature is preferably 80 ° C. or higher from the viewpoint of accelerating the drying and shortening the molding time and from the viewpoint of improving the moisture resistance by the additive, it is preferable that the temperature be 80 ° C. or higher. The temperature is preferably 300 ° C. or less from the viewpoint of preventing the occurrence of the problem that the template strength is not developed. By heating the mold at a temperature within such a temperature range, the moisture resistance of the finally obtained mold can be improved, and drying of the mold material can be advantageously advanced.

Furthermore, during the retention of the mold material in the mold, hot air or superheated steam is blown into the mold to accelerate the filling phase (mold material) in the mold in order to accelerate the evaporation of water. The method is preferably adopted. By such hot air or superheated steam aeration, it is rapidly dried to the inside of the filling phase consisting of the mold material, and the solidification or curing of such filling phase is more advantageously promoted, whereby the solidification (curing) is achieved. In addition to advantageously increasing the speed, it is possible not only to advantageously improve the properties such as the die strength of the resulting mold, but also to advantageously contribute to the shortening of the molding time of the mold. In addition, in order to promote the solidification or hardening of the mold material more advantageously during the holding of the mold material in the mold, a carrier gas consisting of at least one of carbon dioxide, argon, nitrogen, helium and air is molded. A method of blowing into the mold and venting the filling phase is preferably employed. At this time, carbon dioxide acts as a curing agent, and argon, nitrogen, helium and air act as solidification accelerators. The air is preferably air from which part or all of the water vapor has been removed (dry air), and dry air having a humidity of 50% or less, more preferably dry air having a humidity of 30% or less is used. By neutralizing the water-soluble inorganic binder with a carrier gas, it is possible to further accelerate the solidification or curing of the mold material. In addition, although ventilation of hot air or superheated steam and ventilation of carrier gas may be performed only one or the other, it is also possible to implement both, and ventilation of hot air or superheated steam and ventilation of carrier gas are also possible. It is possible to carry out simultaneously, ventilating the carrier gas after ventilating hot air or superheated steam, or ventilating hot air or superheated steam after ventilating the carrier gas. In addition, after the mold material in a wet state is filled in the cavity of the molding die, if it is during holding in the molding die, it does not matter whether the hot air or the like and / or the carrier gas is ventilated at any timing. Absent.

In addition, in order to accelerate the solidification or curing by heating, the carrier gas which is obtained by converting the organic acid, the ester, the monohydric alcohol and the like exemplified above as the curing agent into a gas or mist is inside the mold. You may ventilate.

On the other hand, with regard to the molding of a mold using a wet mold material (coated sand) according to the present invention, by adding a curing agent in the mold other than the method of heating in the mold as described above, A method of solidifying or curing the mold material, or a method of solidifying or curing the mold material by depressurizing the inside of the mold filled with the mold material can also be employed.

The method of adding the curing agent into the molding die is to cause the curing to proceed by the reaction between the water-soluble inorganic binder and the curing agent. As a method of adding the curing agent, a curing agent is added to the mold material before filling into the mold, and the mold material to which the curing agent is added is filled into the mold, and in the mold. It is possible to add the curing agent to the filled mold material by aerating it as a carrier gas. In addition, while curing by the curing agent proceeds while holding in the mold, hot air or superheated steam may be blown into the mold in order to accelerate the evaporation of water. Furthermore, in order to accelerate the solidification or curing of the mold material more advantageously, a carrier gas consisting of at least one of carbon dioxide, argon, nitrogen, helium and air may be blown into the mold. When the addition of the curing agent is performed, heating of the mold is not necessarily required, but in order to accelerate solidification or curing more advantageously, it is preferable to heat the mold. In addition, as a curing agent that can be used here, organic acids such as carbon dioxide (carbonated water) listed above as curing agents, esters such as methyl formate, monohydric alcohols such as methanol, and the like are similarly exemplified. I can do it.

On the other hand, in the method of reducing the pressure in the mold, the mold material filled in the cavity of the mold is dried and solidified by the reduced pressure. As a pressure reduction method, for example, pressure reduction in the inside of the mold by a known suction means and the like can be mentioned. Further, when the pressure in the mold is reduced, hot air or superheated steam may be blown into the mold in order to accelerate the evaporation of water. Furthermore, in order to accelerate the solidification or curing of the mold material more advantageously, a carrier gas consisting of at least one of carbon dioxide, argon, nitrogen, helium and air may be blown into the mold. When the pressure of the mold is reduced, heating of the mold is not always required, but in order to accelerate solidification or curing more advantageously, it is preferable to heat the mold.

And, in any of the molds obtained according to the above-described manufacturing method using the wet mold material according to the present invention, and the molds obtained according to other manufacturing methods, the following excellent effects are advantageously enjoyed. It is possible. That is, when casting is carried out using such a mold, the heat produced by the molten metal effectively decomposes the organic compound contained in the solid coating layer on the surface of the foundry sand, and such thermal decomposition generates a gas. From the point of view, the disintegrability of the mold after casting becomes good. The wet mold material of the present invention contains the organic compound in the solid coating layer on the surface of the foundry sand, but in the whole mold material, the content of the organic compound is constituted using the organic caking agent. When casting is carried out using a mold consisting of the wet mold material of the present invention, the amount of gas generation at that time is an organic binder, since it is very small compared to the mold material to be Compared to the case of using a mold made of mold material, there is an advantage that it is much less. In particular, the template material is produced such that the amount of gas generated when heating the template finally obtained at 1000 ° C. for 240 seconds is 3 to 30 ml, preferably 4 to 28 ml, more preferably 6 to 20 ml per 1 g of the template It is preferable to prepare

In addition, casting is carried out using a mold consisting of a wet mold material according to the present invention, and in casting sand (recovered sand) recovered from the casting mold after such casting, an organic compound present on the casting sand surface Since the solidified or hardened material of the water-soluble inorganic binder is in a state of being easily peeled off from the surface of the casting sand by the gas generated by the thermal decomposition of the powder, dry recovery treatment is performed on such recovered sand. It is possible to reproduce easily.

Here, the dry regeneration treatment for recovered sand may be any method as long as it is a dry regeneration treatment method conventionally known as a regeneration method for recovered sand. In general, a method of treating recovered sand comprising at least a polishing treatment and optionally including a calcination treatment, a classification treatment and the like is called a dry regeneration treatment.

In the polishing process in the dry regeneration process, the deposit remaining on the surface of the recovered sand is scraped off. Specifically, the recovered sand is charged into the rotating rotor, where it is broken into single particles of casting sand, and further, deposits on the surface of the casting sand particles (water-soluble inorganic caking agent) The solidified material or hardened material) is scraped off. The polishing method is not particularly limited, and examples thereof include polishing using a rotary reclaimer, a sandflusher, a sand Shiner or the like. In addition, various polishing conditions such as polishing time in the polishing process are appropriately determined in accordance with the adhesion state of the deposit on the surface of the recovered sand.

In addition, the firing treatment is carried out for the purpose of burning and removing organic compounds, dust, impurities, and the like of the coating layer adhering to the recovered sand. In the firing process, for example, a roasting furnace such as a rotary kiln or a tunnel kiln is used, and the recovered sand is fired in the furnace while throwing the recovered sand into the roasting furnace as needed. The firing temperature in the roasting furnace is 200 to 700 ° C., preferably 300 to 700 ° C., more preferably 350 to 650 ° C., and still more preferably 400 to 600 ° C. If the firing temperature is lower than 200 ° C., there is a risk that dust and the like adhering to the recovered sand may not be sufficiently burned. On the other hand, when the firing temperature exceeds 700 ° C., the water-soluble inorganic binder remaining on the surface of the recovered sand may be sintered, and it may be difficult to separate from the surface of the sand particles. Such baking treatment may be performed before, after, or before or after the above-mentioned polishing treatment.

Classification is generally carried out after the above-mentioned polishing treatment or after the firing treatment if such firing treatment is carried out after the polishing treatment, and the foundry sand taken out from the above-described process step. A process of flowing the treated material by an air flow to remove fine powder contained in such a cast sand process by a dust collector, and a sieving process of removing foreign matter contained in the cast sand process by a sieve have. Specifically, in the dust collection step, the cast sand processing product is made to flow by the air flow, and the fine powder such as shavings, dust and fine powder contained in the cast sand processing product can not be removed in the previous steps. The body is removed by a driven dust collector, which effectively removes minute residues from the foundry sand treatment. Further, in the sieving process, by classifying the particle size of the foundry sand processing material using a sieve, the foreign matter contained in such a foundry sand processing material, which could not be removed in the previous steps, is removed. Thereby, sand of appropriate particle diameter is selectively taken out.

In addition, the classification process employ | adopted in this invention is not limited to what has the above-mentioned dust collection process and a sieving process, For example, it has only any one of a dust collection process and a sieving process. However, there is no problem even if the dust collection process is performed after the sieving process is performed. Furthermore, the classification step may adopt any other known method as long as the molding sand can be classified to a predetermined size.

And, as described above, the foundry sand regenerated by the method for reclaiming recovered foundry sand according to the present invention is again provided to the manufacturing process of the mold material and the molding process of the mold to provide the foundry sand having excellent properties. It will be used to advantage.

Hereinafter, the present invention will be more specifically clarified using some examples, but the present invention should not be construed as limiting in any way by the description of such examples. Should be understood. In the following examples and comparative examples, “%” and “parts” are all indicated on a mass basis unless otherwise noted. In addition, measurement of viscosity of liquid caking agent composition, measurement of solubility of organic compound in water, measurement of gas generation amount of mold made of mold material (coated sand: CS) obtained in Examples and Comparative Examples, The evaluation of the cast surface, the disintegratability and the abrasive removability was performed as follows.

-Measurement of viscosity of liquid caking agent composition-
According to "9. Viscosity measurement method with a single cylindrical shape rotary claymeter" defined in JIS-Z-8803-2011 "Viscosity measurement method of liquid", using the device of the same principle as the device described there The viscosity (cP) at 25 ° C. of the liquid caking agent composition used in Examples and Comparative Examples is measured. In addition, when not using additives, such as a silicon dioxide particle in the case of manufacture of CS, a liquid caking agent composition means water glass aqueous solution or potassium carbonate aqueous solution itself, and CS is used using an additive. When manufacturing, it means a liquid obtained by adding an additive to a water glass aqueous solution or the like.

-Measurement of water solubility of organic compounds-
10 g of the organic compound is placed in a flask, and 100 g of water at 25 ° C. is further charged into the flask and stirred for 1 hour. Then let it stand for 1 hour. The supernatant in the flask after standing is precisely collected in 10 ml with a hole pipet etc. and transferred to an evaporation dish of known mass (mass: W1 (g)). Evaporate, dry, and solidify with a gas burner or the like so as not to bump. Next, the dried and solidified sample is thoroughly dried in a drier at 110 ° C. for 3 hours or more together with an evaporation pan, and the mass (W2 (g)) is measured. The dissolved amount (W3 (g)) of the organic compound is determined from the following equation in consideration of the mass of the evaporating dish.
W3 (g) = (W2-W1) x 10
The solubility of the organic compound in water at 25 ° C. is calculated from the following formula using W3 calculated as described above.
Solubility (mass%)
= {Dissolved amount / water amount} x 100 = {W3 / 100} x 100

-Measurement of gas generation-
Using each CS, a cylindrical test piece of 3 cm in diameter and 5 cm in length is molded, and the test piece is put in a quartz glass tube of 4.5 cm in diameter and 45 cm in length, and attached with a glass tube. Seal with silicone rubber. Using a horizontal casting sand dilatometer EOS-3 (product name, manufactured by Ozawa Scientific Co., Ltd.), the test piece is heated at 1000 ° C. for 4 minutes together with the glass tube. The amount of gas generated is measured every 30 seconds with a wet gas meter W-NK type (product name, manufactured by Shinagawa Co., Ltd.). The total amount of gas generated (total gas generation amount) generated 4 minutes after the start of heat exposure was divided by the mass of the test piece to obtain the gas generation amount.
Gas generation amount (ml / g)
= [Total gas generation amount (ml) after 4 minutes] / [specimen mass (g)]

-Collapse test-
First, as shown in FIG. 1, a half hollow main mold 6 having a pouring inlet 2 at the upper part and a core fixing part 4 of the core at the lower part (cavity diameter: Within 6 cm, height: 6 cm), circular fixed non-air element 10 (diameter: 5 cm, height: 5 cm) with baseboard 8 made using each CS is adhesively fixed with base wood fixing part 4 After that, the half mold half molds 6 are bonded and fixed to each other to make a casting test sand mold 12. In order to prevent leakage of the molten metal at the time of casting, the bonded main mold is clamped with a vise or wound, or a wire is wound and fixed firmly. Next, molten iron FC150 (temperature 1350 ± 50 ° C.) is poured from the pouring inlet 2 of the sand mold 12 for casting test and solidified, and then the main die 6 is broken, and the cylindrical casting shown in FIG. 16 is taken out, and the round non-aircraft 10 is discharged by striking the casting 16 at room temperature using an air hammer. At the time of such discharge, the chipping pressure is 0.3 MPa, and an impact is applied to the casting 16 every three seconds with an air hammer. Then, the ease of discharging CS (hereinafter, referred to as core CS) constituting the circular non-airspacer 16 from the casting 16 is evaluated in five steps in accordance with the criteria shown below. In the present invention, A to C pass.
A: All core CS are discharged within 10 strikes.
B: All core CSs were discharged within 30 hits.
C: All core CSs are discharged within 60 hits.
D: The core CS is discharged in an amount of 50% to less than 100% after 60 hits.
E: The core CS is discharged in an amount of 0 to less than 50% after 60 impacts.

-Evaluation of casting surface-
The cast obtained in the above-mentioned disintegration test is cut in half, the condition of the cast surface (skin of the cast) is checked visually and by hand, and evaluated in four stages according to the criteria shown below. In the present invention, ◎ and を are passed.
◎: No sticking was observed, and the surface was smooth.
○: Although burn-in is not observed, roughness is observed on the surface.
Δ: A part of the cast surface is seized and a rough surface is also observed.
X: Burn-in is observed on the entire surface of the cast surface, and roughness is also observed on the surface.

-Abrasive peelability test-
100 g of the sand (recovered sand) which was taken out in the above-mentioned disintegration test and which was a circular non-air-core was put into a ball mill and polished for 1 hour. Thereafter, sieving is carried out with 200 mesh for 1 minute to separate into foundry sand and exfoliated fine powder, the amount of obtained fine powder is measured, and the ease of exfoliation in recovered sand is determined in 5 stages according to the criteria shown below. Evaluate. In the present invention, A to C are accepted.
A: The amount of fine powder is 2% by mass or more with respect to the mass of casting sand.
B: The amount of fine powder is 1% by mass or more and less than 2% by mass with respect to the mass of casting sand.
C: The amount of fine powder is 0.5% by mass or more and less than 1% by mass with respect to the mass of casting sand.
D: The amount of fine powder is 0.25% by mass or more and less than 0.5% by mass with respect to the mass of casting sand.
E: The amount of fine powder is less than 0.25% by mass with respect to the mass of casting sand.

Moreover, about the novolak-type phenol resin etc. which were used when manufacturing each CS, what was manufactured according to the following procedures, or the commercial item was prepared, respectively.

(1) Novolak Type Phenolic Resin In a reaction vessel equipped with a thermometer, a stirrer and a condenser, 940 parts of phenol, 479 parts of 47% formalin and 2.8 parts of oxalic acid were charged. Then, the temperature in the reaction vessel is gradually raised to reach the reflux temperature, and then the reaction is carried out by reflux for 90 minutes, and the reaction solution is heated and concentrated under reduced pressure until the temperature reaches 170 ° C. A novolac phenolic resin having a weight average molecular weight (Mw) of 2900 was obtained.

(2) Resol type phenolic resin A
As the resol type phenol resin A, SP400 (trade name, Mw: 2100) manufactured by Asahi Organic Materials Co., Ltd., which is an ammonia resol type phenol resin, was used.

(3) Resol type phenolic resin B
In a reaction vessel equipped with a thermometer, a stirrer and a condenser, 940 parts of phenol, 957 parts of 47% formalin and 20 parts of potassium hydroxide were charged. Then, the temperature in the reaction vessel was gradually raised to 75 ° C. in 60 minutes and reacted at that temperature for 5 hours. After that, dehydration was performed to 80 ° C. under reduced pressure to obtain resol-type phenol resin B having a weight average molecular weight (Mw) of 1,500.

(4) Phenolic Urethane Resin A benzylic ether type phenol resin (Asahi Organic Material Co., Ltd., trade name: CBP-160EH, Mw: 1200) and a polyisocyanate resin, polymeric MDI (Asahi Organic Material Co., Ltd .; CB-) In preparing MT3) and forming a coating layer on the surface of molding sand, a mixture of the two resins mixed in a ratio of 1: 1 (mass ratio) was used.

(5) Polyvinyl acetate As poly (vinyl acetate), a polyvinyl acetate solution of Gohtheil M35-X6 (manufactured by Japan Synthetic Chemical Industry Co., Ltd., 35% solution in methanol) was used.

(6) Starch Starch manufactured by Wako Pure Chemical Industries, Ltd. was used as a starch solution (concentration: 25%) obtained by dissolving it in hot water at 70 ° C.

-Production example 1 of wet condition CS-
As cast sand, Lunamos # 60 (trade name, manufactured by Kao Quaker Co., Ltd.), which is a commercially available artificial sand for casting, was prepared, and a novolac phenolic resin was prepared as an organic compound. Then, after heating Lunamos # 60 to a temperature of about 130 ° C., it is introduced into a whirl mixer (manufactured by Enshu Iron Works), and further, a ratio of 0.3 part of novolac type phenolic resin to 100 parts of Lunamos # 60 The mixture is added for 3 minutes and the water is evaporated, while stirring and mixing until the sand lumps are disintegrated and then taken out, a solid of novolak-type phenolic resin is formed on the surface of the foundry sand particles. A coating layer was formed. The film thickness of the formed solid coating layer was calculated to be 0.2 μm from the average particle diameter of spherical foundry sand particles and the addition amount of the foundry sand and the organic compound (novolak-type phenolic resin).

Then, as water glass which is a water-soluble inorganic binder, a commercial product: No. 1 sodium silicate (trade name: manufactured by Fuji Chemical Co., Ltd., a molar ratio of SiO ₂ / Na ₂ O: 2.0) is prepared. A water glass aqueous solution having a solid component (concentration) of 31% and a viscosity at 25 ° C. of 11 cP was prepared using Then, the casting sand provided with a solid coating layer on the surface is charged into a Shinagawa universal stirrer (5DM-r type, manufactured by Dalton Co., Ltd.) at normal temperature, and a water glass aqueous solution is further added. Add 2.5 parts (solid component: 0.775 parts) to 100 parts of Lunamos # 60, perform kneading for 3 minutes, stir until it becomes uniform, take out, and then take out. Thus, a wet mold material (CS1) composed of a mixture of a molding sand and a water glass aqueous solution provided with a coating layer on the surface was obtained. When the water content of CS1 was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production examples 2 to 5 of wet state CS
In Production Example 1 of the wet CS, the above Production Example 1 was used except that the use amount of novolac type phenol resin at the time of forming the coating layer was 0.5 parts, 1 part, 2 parts, 5.5 parts, respectively. A wet mold material (CS2-CS5) was obtained according to the same procedure. The obtained water content of CS2 to CS5 was calculated from the addition amount of the added material, and all corresponded to 223% by mass of the solid content of water glass.

-Production example 6 of wet condition CS-
In the same manner as in the above-mentioned Production Example 4 except that the amount of water glass added is 3.5 parts (solid component: 1.085 parts) in Production Example 4 of the wet CS, a wet mold material ( Got CS6). When the water content of CS 6 obtained was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 7 of wet condition CS-
In Production Example 1 of wet CS, the amount of novolac type phenol resin used at the time of forming a coating layer is 0.8 parts, and silicon dioxide particles 971U (trade name, manufactured by Elchem Co., average particle diameter: 0) A wet mold material (CS7) was obtained according to the same procedure as in Production Example 1 except that 1 part of .15 μm) was added to the aqueous solution of water glass. It was the quantity corresponded to 223 mass% of solid content of water glass when computed from the addition amount of the added material of the water content of obtained CS7.

-Production example of wet CS
The above production is performed in Production Example 3 of wet CS, except that 0.01 part of a silane coupling agent KBE 903 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is added to the novolac phenol resin at the time of forming a coating layer. Following the same procedure as in Example 3, a wet mold material (CS8) was obtained. It was the quantity corresponded to 223 mass% of solid content of water glass when computed from the addition amount of the added material of the water content of obtained CS8.

-Production example 9 of wet condition CS-
The same procedure as in Production Example 3 above, except that 0.025 parts of KBE 903 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silane coupling agent, is added to a water glass aqueous solution in Production Example 3 of wet CS. A wet mold material (CS9) was obtained according to When the obtained water content of CS9 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 10 of wet condition CS-
The same procedure as in Production Example 8 except that 0.025 parts of KBE 903 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silane coupling agent, is added to the aqueous solution of water glass in Production Example 8 of wet CS. A wet mold material (CS10) was obtained according to When the obtained water content of CS10 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 11 of wet condition CS-
In the above Preparation Example 3 except that in the Preparation Example 3 of the wet CS, 0.075 parts of a borate (sodium tetraborate decahydrate) as a moisture resistance improver is added to the water glass aqueous solution. A wet mold material (CS11) was obtained according to the same procedure. When the obtained water content of CS11 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 12 of wet condition CS-
A wet mold material (CS12) was prepared according to the same procedure as in Production Example 3 above, except that a coating layer was formed using Resol type phenolic resin A instead of the novolak type phenolic resin in Production Example 3 of wet CS. Got). When the water content of the obtained CS12 was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of the water glass.

-Production example 13 of wet condition CS-
In Production Example 3 of wet CS, the coating layer is formed using the resol-type phenol resin B instead of the novolak-type phenol resin and setting the amount to 1.6 parts (solid content: 1.0 part) In the same manner as in Production Example 3 above, a wet mold material (CS13) was obtained. When the obtained water content of CS13 was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of the water glass.

-Production example 14 of wet state CS-
The procedure of Production Example 3 is repeated except that the coating layer is formed according to the following procedure in order to replace the organic compound forming the coating layer from the novolak type phenol resin with the phenol urethane resin in Production Example 3 of wet CS. The wet mold material (CS14) was obtained. That is, Lunamus # 60 is introduced into a whirl mixer (manufactured by Enshu Iron Works) at 130 ° C., and a benzylic ether type phenol resin and a polyisocyanate resin for constituting a phenol urethane resin are further added at a mass ratio of 1: 1, The total amount of them is added in an amount of 1.4 parts and kneading is carried out in a mixer, and a benzylic ether type phenol resin and a polyisocyanate resin are reacted to obtain a phenol urethane resin (solid content: 1.0 part) ), Cured and solidified until it was stirred and mixed, then taken out. When the obtained water content of CS14 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 15 of wet condition CS-
In Production Example 3 of wet CS, the novolak type phenol resin is replaced with a polyvinyl acetate solution (methanol 35% solution), the amount used is 1.54 parts (solid content: 1.0 part), and a coating layer is formed A wet mold material (CS15) was obtained according to the same procedure as in Production Example 3 except that the solvent was evaporated. When the water content of the obtained CS15 was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of the water glass.

-Production example of wet condition CS-
In Production Example 3 of wet CS, using a starch solution (concentration: 25%) prepared by dissolving starch in hot water at 70 ° C. instead of novolak-type phenolic resin, the amount used is 4 parts (solid content: 1 A wet mold material (CS16) was obtained according to the same procedure as in the above Production Example 3 except that the content was changed to .0 part). When the water content of the obtained CS16 was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of the water glass.

-Production example 17 of wet condition CS-
In Production Example 3 of wet CS, a commercially available product No. 1 sodium silicate (trade name: Fuji Chemical Co., Ltd., molar ratio of SiO ₂ / Na ₂ O: 2.0) is used as a water glass aqueous solution. The wet mold material (CS17) was prepared according to the same procedure as in Production Example 3 except that a water glass aqueous solution was prepared so that the solid component (concentration) was 46% and the viscosity at 25 ° C was 1050 cP. Got). When the water content of the obtained CS17 was calculated from the added amount of the added material, it was an amount corresponding to 117% by mass of the solid content of the water glass.

-Production example 18 of wet condition CS-
In Production Example 3 of the wet CS, 0.15 parts of hexamethylenetetramine was added at the time of kneading to form a solid coating layer made of novolac-type phenolic resin on the casting sand surface, and then this coating layer was formed. A casting mold material (CS18) in a wet state was obtained according to the same procedure as in Production Example 3 except that casting sand was placed in a thermostat at 180 ° C. for 30 minutes to accelerate the curing of the novolak-type phenolic resin. It was the quantity corresponded to 223 mass% of solid content of water glass when computed from the addition amount of the added material of the water content of obtained CS18.

-Production example 19 of wet condition CS-
In Production Example 12 of wet CS, after forming a solid coating layer of resol type phenolic resin A on the surface of casting sand, casting sand on which such a coating layer is formed is placed in a thermostat at 180 ° C. for 30 minutes. Then, a wet mold material (CS19) was obtained according to the same procedure as in Production Example 12 except that the curing of resol type phenol resin A was promoted. When the obtained water content of CS19 was calculated from the added amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 20 of wet condition CS-
In Production Example 3 of wet CS, using a potassium carbonate aqueous solution prepared so that the solid component (concentration) of potassium carbonate is 50% and the viscosity at 25 ° C. is 8 cP, instead of the water glass aqueous solution. A wet mold material (CS20) was obtained according to the same procedure as in Production Example 3 except that the amount used was 3 parts. When the obtained water content of CS20 was calculated from the addition amount of the added material, it was an amount corresponding to 100% by mass of the solid content of potassium carbonate.

-Production example 21 to 24 of wet condition CS
In the production examples 1, 7, 8 and 11 of the wet CS, the procedure similar to the above production examples 1, 7, 8 and 11 is carried out except that the step of forming a solid coating layer is not carried out. The mold material (CS21 to CS24) was obtained. The water content of the obtained CS21 to CS24 was calculated from the added amount of the added material, and all corresponded to 223% by mass of the solid content of the water glass.

-Production example of wet CS
A wet mold material (CS25) was obtained according to the same procedure as in Production Example 20 except that the step of forming a solid coating layer was not performed in Production Example 20 of wet CS. When the water content of the obtained CS25 was calculated from the added amount of the added material, it was an amount corresponding to 100% by mass of the solid content of potassium carbonate.

-Production example 26 of wet state CS-
The same procedure as in Production Example 25 above, except that 0.03 part of KBE 903 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silane coupling agent, is added to a potassium carbonate aqueous solution in Production Example 25 of wet CS. A wet mold material (CS26) was obtained according to When the obtained water content of CS26 was calculated from the addition amount of the added material, it was an amount corresponding to 100% by mass of the solid content of potassium carbonate.

-Production example 27 of wet condition CS-
A wet CS preparation example 25 was carried out according to the same procedure as in the above-mentioned preparation example 25 except that 0.09 part of sodium tetraborate decahydrate as a moisture resistance improver was added to the aqueous solution of potassium carbonate. The mold material (CS27) was obtained. When the obtained water content of CS27 was calculated from the addition amount of the added material, it was an amount corresponding to 100% by mass of the solid content of potassium carbonate.

-Example of mold formation (Examples 1 to 20, Comparative Examples 1 to 7)-
After filling CS 1 to 27 manufactured according to the above-described procedures into a molding die heated to 150 ° C., the CS 1 to 27 are held in the molding die, and each CS filled in such a molding die is cured Thus, a mold was produced which was used as a circular non-air-filled test piece (diameter: 5 cm × height: 5 cm). The CSs used for producing the molds (test pieces) according to each of Examples 1 to 20 and Comparative Examples 1 to 7 are as shown in Tables 1 to 4 below.

As apparent from Tables 1 to 4, in the mold (Examples 1 to 20) obtained using the wet mold material according to the present invention, the mold has excellent disintegration after casting and is obtained. It is recognized that the casting surface of the cast product is good. In addition, with regard to sand recovered after casting, it has been found that solidified or hardened material of water-soluble inorganic binder adhered thereto can be easily removed by polishing, according to the present invention. It is also confirmed that the wet mold material is easy to regenerate the foundry sand.

-Production example of wet CS, 29-
In Production Example 7 of wet CS, silicon dioxide particles 971U (trade name, manufactured by Elchem Co., average particle size: 0.15 μm) as a filling improver are each silicon dioxide particles HS312 (trade name, Nippon Steel Sumikin Materials shares) Same as in Production Example 7 except that aluminum oxide particles AZ-75 (trade name, manufactured by Nippon Steel & Sumikin Materials Co., Ltd., average particle size: 2.5 μm) are used instead of the company-made average particle size: 9.5 μm A wet mold material (CS28, CS29) was obtained according to the following procedure. When the water content of the obtained CS28 and CS29 was calculated from the added amount of the added material, it was an amount corresponding to 226% by mass of the solid content of the water glass.

-Production example of wet CS, 31-
In Production Example 11 of wet CS, the above Production Example 11 except that the borate (sodium tetraborate decahydrate) is replaced with sulfate (lithium sulfate) and carbonate (basic zinc carbonate), respectively. A wet mold material (CS30, CS31) was obtained according to the same procedure as in. When the water content of the obtained CS30 and CS31 was calculated from the added amount of the added material, it was an amount corresponding to 226% by mass of the solid content of the water glass.

-Production example of wet CS
In the above Production Example 11 of Wet CS, the above-mentioned production is performed except that 1 part of silicon dioxide particles 971U (trade name, manufactured by Elchem, average particle size: 0.15 μm) as a filling improver is added to a water glass aqueous solution. Following the same procedure as in Example 11, a wet mold material (CS32) was obtained. When the water content of CS32 obtained was calculated from the added amount of the added material, it was an amount corresponding to 226% by mass of the solid content of water glass.

-Production example of wet CS
In the above Production Example 30 of the wet CS, except that 1 part of silicon dioxide particles 971 U (trade name, manufactured by Elchem, average particle size: 0.15 μm) as a filling improver is added to an aqueous solution of water glass, Following the same procedure as in Example 30, a wet mold material (CS33) was obtained. When the obtained water content of CS33 was calculated from the addition amount of the added material, it was an amount corresponding to 226% by mass of the solid content of the water glass.

-Production example 34 of wet condition CS-
In the above Production Example 31 of the wet CS, except that 1 part of silicon dioxide particles 971 U (trade name, manufactured by Elchem, average particle size: 0.15 μm) as a filling improver is added to an aqueous solution of water glass, Following the same procedure as in Example 31, a wet mold material (CS34) was obtained. When the obtained water content of CS34 was calculated from the addition amount of the added material, it was an amount corresponding to 226% by mass of the solid content of the water glass.

90, after blowing and filling each CS into a mold heated to 150 ° C. at a gauge pressure of 0.3 MPa using each of CS3, CS7, CS8, CS9, CS10, CS11 and CS28 to CS34 By holding for second, a test piece for width test (width: 1 cm × height: 1 cm × length: 8 cm) was produced. The moisture absorption strength retention of the obtained test pieces was calculated according to the following procedure (Examples 21 to 33). The results are shown in Tables 5 and 6 below.

-Moisture absorption strength retention rate-
The breaking load of the test piece obtained using each CS is measured using a measuring instrument (a digital casting sand strength tester manufactured by Takachiho Seiki Co., Ltd.), and then, using this measured breaking load The bending strength was calculated by the following equation. In addition, the measurement of the breaking load was performed using the test piece of the normal temperature 1 hour after shaping | molding passed.
Breaking strength (N / cm ² ) = 1.5 × LW / ab ²
[Wherein L: distance between supporting points (cm), W: breaking load (N), a: width of the test piece (cm), b: thickness of the test piece (cm). ]
Next, put water, a glycerol mixed solution and 4 pieces of clogged wire netting in a container, and place each test piece on the metal netting so that the test piece does not touch the water and glycerol mixed solution (20% concentration), The whole container was placed in a temperature controller and kept at 40 ° C. for 24 hours to degrade each test piece by moisture absorption. The flexural strength of each test piece after the moisture absorption deterioration was measured in the same manner as described above. From the flexural strength before moisture absorption and the flexural strength after moisture absorption, the moisture absorption strength retention was calculated based on the following formula.
Moisture absorption strength retention rate (%) = (post-moisture strength after bending / strength before moisture absorption) × 100

As apparent from Table 5 and Table 6, by adding a borate, which is a moisture resistance improver, a sulfate, a carbonate or the like to the binder composition, or by adding silicon dioxide particles. It is recognized that the moisture absorption strength retention rate of the finally obtained mold is significantly improved. In addition, although it has been found that the retention of moisture absorption strength of the mold is improved by incorporating the coupling agent in any of the solid coating layer and the liquid binder composition, the solid coating layer and the liquid It is recognized that the moisture absorption strength retention rate of the mold is further improved by incorporating the coupling agent into both of the binder compositions of the present invention.

-Production example of wet CS
In the same manner as in the above-mentioned Production Example 8 except that the amount of the silane coupling agent added to the novolak-type phenolic resin is 0.03 part in Production Example 8 of the wet CS, a wet mold material ( Got CS 35). When the obtained water content of CS35 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 36 of wet condition CS-
The wet mold material (CS36) was prepared according to the same procedure as in Production Example 9 except that the addition amount of the silane coupling agent added to the aqueous solution of water glass was changed to 0.075 parts in Production Example 9 of wet CS. Got). When the obtained water content of CS36 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

-Production example 37 of wet state CS-
In Production Example 10 of wet CS, 0.03 parts of the addition amount of the silane coupling agent added to the novolak-type phenol resin and 0.075 parts of the addition amount of the silane coupling agent added to the water glass aqueous solution A wet mold material (CS37) was obtained according to the same procedure as in Production Example 10 except for the above. When the obtained water content of CS37 was calculated from the addition amount of the added material, it was an amount corresponding to 223% by mass of the solid content of water glass.

Using each of CS3, CS8, CS9, CS10 and CS35 to CS37, after blowing and filling each CS at a gauge pressure of 0.3 MPa in a mold heated to 150 ° C., hold for 90 seconds Test pieces (width: 1 cm × height: 1 cm × length: 8 cm) were produced. The bending strength of the obtained test piece was calculated according to the following procedure (Examples 34 to 40). The results are shown in Table 7 below.

-Break strength-
The breaking load of the test piece obtained using each CS is measured using a measuring instrument (a digital casting sand strength tester manufactured by Takachiho Seiki Co., Ltd.), and then, using this measured breaking load The bending strength was calculated by the following equation. In addition, the measurement of the breaking load was performed using the test piece of the normal temperature 1 hour after shaping | molding passed.
Breaking strength (N / cm ² ) = 1.5 × LW / ab ²
[Wherein L: distance between supporting points (cm), W: breaking load (N), a: width of the test piece (cm), b: thickness of the test piece (cm). ]

As apparent from Table 7 above, in the template material according to the present invention, the final state is achieved by including a coupling agent in either or both of the solid coating layer and the water-soluble inorganic binder. It can be seen that the strength is improved in the mold obtained in In particular, it is recognized that the incorporation of the coupling agent into each of the solid coating layer and the water-soluble inorganic binding agent results in a mold which exhibits very high mold strength by synergetic effect.

2 Molten metal injection port 4 Baseboard fixing part 6 Main type 8 Baseboard section 10 Core 12 Sand type 14 Waste core outlet 16 Casting

Claims

1. A wet mold material characterized in that a foundry sand coated with a solid coating layer containing an organic compound is coated with a liquid caking agent composition containing a water-soluble inorganic caking agent.
The mold material according to claim 1, wherein the thickness of the solid coating layer is 0.1 to 6 μm.
The mold material according to claim 1 or 2, wherein the organic compound is at least one selected from the group consisting of a cross-linking curable resin and a cured product thereof, a thermoplastic resin, and a carbohydrate.
The mold material according to claim 3, wherein the crosslinkable curing resin is a phenol resin.
The template material according to any one of claims 1 to 4, wherein the organic compound is a polymer compound having a weight average molecular weight of 300 or more.
The mold material according to any one of claims 1 to 5, wherein the solubility of the organic compound in 100 g of water at 25 ° C is 1% by mass or less.
The mold material according to any one of claims 1 to 6, wherein the solid coating layer contains a coupling agent.
The mold material according to any one of claims 1 to 7, wherein a solid content of the water-soluble inorganic binder in the liquid binder composition is 10 to 80% by mass.
The mold material according to any one of claims 1 to 8, wherein the liquid binder composition contains a coupling agent.
The mold material according to any one of claims 1 to 9, wherein the liquid binder composition contains inorganic oxide particles.
11. The template material according to claim 10, wherein the inorganic oxide particles are silicon dioxide particles.
The mold material according to any one of claims 1 to 11, wherein the liquid caking agent composition contains a moisture resistance improver.
The mold material according to any one of claims 1 to 12, wherein the water-soluble inorganic binder is water glass.
The mold material according to any one of claims 1 to 13, wherein the liquid binder composition comprises water.
The mold shape | molded using the mold material in any one of Claims 1-14.
The mold according to claim 15, wherein a gas generation amount when heated at 1000 ° C for 240 seconds is 3 to 30 ml per 1 g.
Forming a solid coating layer containing an organic compound on the surface of the casting sand;
Adding a liquid caking agent composition containing a water-soluble inorganic caking agent to the foundry sand on which the solid coating layer is formed, and kneading or mixing;
A method of producing a wet mold material having
The organic compound is a cross-linking curable resin, and the method comprises the step of curing the cross-linking curable resin contained in the solid coating layer after forming the solid coating layer on the surface of the casting sand. Item 18. A method for producing a mold material according to Item 17.
The method for producing a mold material according to claim 17 or 18, wherein the water-soluble inorganic binder is water glass.
The method for producing a mold material according to any one of claims 17 to 19, wherein the liquid binder composition contains water.
After filling the mold material according to any one of claims 1 to 14 into a mold, the mold material is held in the mold, and a) the mold is heated by heating the mold; b) the mold The target mold can be obtained by solidifying or curing the mold material filled in the mold by adding a curing agent inside or c) reducing the pressure in the mold. A method for producing a mold characterized by the present invention.
The method for producing a mold according to claim 21, wherein hot air or superheated steam is ventilated in the mold while holding the mold.
The method for manufacturing a mold according to claim 21 or 22, wherein a carrier gas consisting of at least one of carbon dioxide, argon, nitrogen, helium and air is allowed to flow into the mold while holding the mold.
The method for manufacturing a mold according to any one of claims 21 to 23, wherein the mold is heated to a temperature of 80 属 C to 300 属 C.
After casting is performed using a mold made of a solidified or hardened material of a mold material according to any one of claims 1 to 14, casting sand is recovered from the mold and subjected to dry regeneration treatment. A method of reclaiming foundry sand characterized by applying to obtain reclaimed sand.