JPH11207432A - Molding composition for mold and molding method for mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide kneaded sand which uses binder containing water soluble saccharides for giving high mold strength and wetting resistance as the essential component, aldehyde compound having carbon-carbon double bond and acidic catalyst, and a molding method for a mold, with which this kneaded sand is dried and hardened. SOLUTION: The molding composition for mold obtd. by a process in which aggregate of one or more kinds among silica sand, zircon sand, olivine sand, chromite sand, alumina sand and mullite sand, to 100 pts.wt. of the aggregate 0.5-10 pts.wt. of the binder containing the water soluble saccharides having 10-50 dextrose equivalent and aldehyde compound having carbon-carbon double bond at the ratio of 50:50-99:1 and added with the water so as to become 20-75 wt.% concn. and to 100 pts.wt. of the solid content of the binder, 0.1-25 pts.wt. of the acid having >=1×10<-5> dissociation constant (ka), are added and mixed, is filled into a mold pattern, and successively, dried and hardened with drying gas or reduced pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for molding a mold having high strength and excellent moisture resistance, and a water-soluble saccharide comprising a water-soluble saccharide having a saccharide composition for imparting high mold strength and moisture resistance as a main component. A kneading sand containing a binder, an aldehyde compound having a carbon-carbon double bond and an acidic catalyst, and using a binder that is crosslinked by drying (hereinafter referred to as “oligo binder M”) and drying the kneaded sand The present invention relates to a molding method of a mold to be cured.

2. Description of the Related Art There are various methods for molding a mold.
There are a wide variety of binders used for this purpose, but they are roughly divided into inorganic binders and organic binders. As a molding method using an inorganic binder, there is a method of hardening a silicate mainly with ferrosilicon (N process), dicalcium silicate (dical method), or CO ₂ gas. A mold using silicate has disadvantages such as poor disintegration after casting and generation of a large amount of waste. As a molding method using an organic binder, a thermosetting mold such as a shell mold method, a room temperature curable mold in which a furan resin or a phenol resin is cured using an acid or an ester, or a urethane resin or a phenol resin in an amine gas, There is a molding method such as a gas-curable mold that is cured with an ester gas or a CO ₂ gas. There are drawbacks such as the generation of odors such as formaldehyde and the deterioration of the working environment due to the use of organic solvents, toxic hardeners or catalysts during mold making using these organic binders. In addition, when pouring, the binder, organic solvent, curing agent, catalyst and the cured product of the binder are thermally decomposed to generate various harmful gases and odors, thereby reducing the working environment in the factory and the external environment around the factory. There are drawbacks that make it worse. On the other hand, as binders of these inorganic binders and organic binders that do not have the above-mentioned drawbacks, there is a technique of using a water-soluble glue binder using a natural product or a dextrin derived from a natural product. Kaisho 52
-120225, JP-A-59-76642, JP-B-3-21254). However, a large amount of a water-soluble glue binder is required to obtain the strength of a practically usable mold, which is not practical. Further, the mold using the water-soluble glue binder has a limitation in the work process that the mold must be poured immediately after molding because the strength of the mold is significantly deteriorated due to the absorption of moisture in the air after molding. Furthermore, when these water-soluble glue binders are stored in an aqueous solution, they are easily rotted by microorganisms and the like, and have drawbacks in storage stability and hygiene.

Problems such as disintegration of inorganic binders and waste sand, lack of mold strength and storage stability of conventional water-soluble glue binders and organic binders, work environment and As a result of intensive studies to obtain a template that has solved the drawbacks such as adverse effects on the external environment, water-soluble saccharides, particularly saccharides having a restricted sugar composition, and a carbon-carbon double bond for cross-linking the water-soluble saccharide have been developed. By using an aldehyde compound and an acidic catalyst as essential components, and using an oligo-binding agent M containing a water-soluble acid-curable resin, an auxiliary agent, a silane coupling agent and a surfactant, the sand is easily disintegrated and the sand can be regenerated. The present invention has succeeded in obtaining a mold that is easy, has excellent mold strength and storage stability, and does not deteriorate the working environment due to generation of harmful odor, and has led to the present invention.

The present invention will be described in further detail. The aggregate used in the present invention includes silica sand, zircon sand, olivine sand, chromite sand, alumina sand, mullite sand and the like. Solids concentration 20 per 100 parts by weight of aggregate
0.5 to 10 parts by weight of ~ 75% by weight oligo binder M,
An object of the present invention is to provide a composition for mold molding obtained by adding 0.1 to 25 parts by weight of an acidic catalyst to 100 parts by weight of the solid content of the oligo binder M and kneading the mixture. One. Still another object is to provide a method for filling a desired model with the composition for molding a mold, drying and curing the composition to mold a mold. The drying method is described in further detail. The temperature is 0 ° C. to 4.9 kPa at a pressure of 4.9 to 390 kPa from the upper part, lower part or side part of the model.
A dry gas (hot air) at 400 ° C. is passed through to forcibly remove moisture. At this time, at the same time, it is more effective to carry out forced drying by reducing the pressure from the portion on the opposite side of the hot air blowing port,
The mold can be cured in a short time. When hot air drying at 80 ° C. or higher is performed, a drying gas at a temperature of 50 ° C. or lower is passed through the mold under the same conditions as the above pressure to cool the mold. At this time, as in the case of forced drying, it is more effective to simultaneously cool the mold under reduced pressure. At the time of drying, it is also possible to use dielectric heating by high frequency, microwave, or the like. However, also in this case, it is necessary, for example, to ventilate the air and forcibly discharge the moisture to the outside. At this time, CO ₂ , He, Ne, Ar,
Obviously, N ₂ can also be used. Further, the mold making method of the present invention can be dried only by reduced pressure. In that case, the kneading sand obtained by using the oligo-binding agent M is filled into a mold, and the mold is placed in a closed container. Then, the pressure in the vacuum box is reduced to 48.0 kPa or less by a vacuum pump, and Forcibly remove water. The pressure in the vacuum box is kept at 48.0 kPa or less until moisture in the mold is removed, and after drying and curing, the pressure is returned to the atmospheric pressure (101.3 kPa), and then the mold is taken out. As shown in FIG. 1, a method of placing a mold in a closed container and drying it in a vacuum is as follows: a closed container (vacuum box) 1 or a mold 2 is moved up and down as indicated by an arrow in FIG.
As shown in FIG. 3, the mold 2 is a slide type in which the mold 2 moves left and right as indicated by the arrow in the figure. Further, as shown in FIG. There is a stationary type in which the mold 2 is placed on the mold 2 and the periphery of the mold 2 is covered with the airtight flexible film 4 to make a vacuum. The water-soluble saccharide used in the present invention includes a natural oligosaccharide and / or a water-soluble saccharide having a dextrose equivalent (hereinafter referred to as “DE”) = 10 to 50 obtained by hydrolyzing starch using an acid or an enzyme. Or a water-soluble saccharide having a molecular weight equivalent to the starch hydrolyzate obtained by hydrolyzing a natural high-molecular saccharide. More preferably, the content of monosaccharide is 1% by weight or less in terms of solid content, 5% by weight or less of disaccharide, 5 to 25% by weight of trisaccharide, and 3 to 15% of tetrasaccharide.
It is a water-soluble saccharide having a saccharide composition of 3% to 20% by weight of pentasaccharide, 3 to 25% by weight of hexasaccharide, and 35% by weight or more of 7 or more saccharides. In addition, by containing an organic compound having an aldehyde group and a double bond as an essential component and an acidic catalyst, the water-soluble saccharide can be crosslinked by drying and curing, thereby improving mold strength and water resistance. Here, when a water-soluble saccharide having a composition deviating from the water-soluble saccharide, particularly an equivalent molecular weight obtained by hydrolyzing a saccharide having a DE of less than 10 or a high-molecular saccharide is used, the solubility in water is low, and Requires a large amount of water, and a long time is required in the mold drying step. In addition, the viscosity when dissolved in water is high, and the kneading property with the sand is deteriorated, and the fluidity of the obtained kneaded sand is also deteriorated. In addition, when a water-soluble saccharide having an equivalent molecular weight obtained by hydrolyzing a saccharide or a high-molecular saccharide having a DE of greater than 50, that is, a water-soluble saccharide containing a large amount of monosaccharide, is used, the water solubility and the viscosity of the aqueous solution are reduced. However, high mold strength after drying and curing cannot be obtained. Also, the amount of the aldehyde compound serving as a cross-linking agent must be large, which is economically disadvantageous and is not suitable as a binder.
On the other hand, DE is a water-soluble saccharide having an equivalent molecular weight obtained by hydrolyzing a saccharide or a high-molecular saccharide having a DE of 10 to 50. In particular, the monosaccharide content is 1% by weight or less in terms of solids, and the disaccharide is 5% by weight. Hereinafter, a saccharide composition of 5 to 25% by weight of trisaccharide, 3 to 15% by weight of tetrasaccharide, 3 to 20% by weight of pentasaccharide, 3 to 25% by weight of hexasaccharide, and 35% by weight or more of 7 or more saccharides. When a water-soluble saccharide is used as a binder, it is easy to prepare an aqueous solution, and since the viscosity of the aqueous solution is low, it has good kneadability with sand and obtains kneaded sand (ie, a composition for mold molding). Good). In addition, a sufficiently high mold strength can be obtained for practical use. In addition, when reacted with a polyfunctional aldehyde compound, a high mold strength and moisture resistance can be obtained by forming a hardly soluble hard film. Oligo binder M in the present invention is a water-soluble, in order to further improve the strength of the mold and maintain the hot strength involved in maintaining the shape of the mold until the molten aluminum or iron at the time of pouring solidifies. It is effective to use at least one of phenol resins, urea resins, melamine resins, and acid-curable resins such as furan resins. It is also effective to use a water-soluble polymer such as polysaccharide, protein, polyvinyl alcohol, sodium polyacrylate, or vinyl acetate resin as an auxiliary agent in the oligo binder M. Further, by adding a silane coupling agent or a surfactant to the oligo-binding agent N, it is possible to obtain higher normal strength and better storage stability of the template. The oligo binder M in the present invention has a solid concentration of 20.
To 75% by weight, preferably 30 to 65% by weight. If the solid content exceeds 75% by weight, the viscosity of the oligo binder M becomes high, and it becomes difficult to sufficiently knead the aggregate and the binder, and the fluidity of the kneaded sand is deteriorated. On the other hand, when the solid content is less than 20% by weight, the amount of water is large and not only takes much time to dry the mold, but also the practically usable strength of the mold cannot be obtained. The mixing ratio of the water-soluble saccharide which is an essential component in the oligo-binding agent M and the organic compound having an aldehyde group and a double bond is such that the saccharide is 50% of the solid content.
~ 99% by weight. If the amount of the saccharide in the solid content exceeds 99% by weight, the ratio of the aldehyde compound is small, the crosslinking point is small, and a sufficient crosslinking effect cannot be obtained. Therefore, the effect on the mold strength and moisture resistance is small. If it is less than 50% by weight, that is, even if the proportion of the aldehyde compound increases, a remarkable crosslinking effect cannot be obtained. In addition, the amount of the crosslinking agent increases, which is economically disadvantageous. Further, an acid is required as a crosslinking catalyst for the crosslinking reaction, and the dissociation constant of the acid is Ka = 1.
An acid catalyst of × 10 ^-5 or more is required. Naturally, an acid having an acid dissociation constant of less than Ka = 1 × 10 ⁻⁵ cannot provide a sufficient catalytic action, so that the cross-linking reaction is not completed during drying and curing, so that sufficient mold strength and moisture resistance cannot be obtained. Examples of the water-soluble saccharide used in the oligo-binding agent M of the present invention include naturally occurring saccharides and saccharides obtained by hydrolyzing a naturally occurring polysaccharide with an acid or an enzyme. , Potato starch, sweet potato starch, corn starch,
The starch is not particularly limited as long as it is a carbohydrate such as high amylose corn starch, waxy corn starch, wheat starch, tapioca starch, sago starch and the like, cellulosic material, chitin, mannan, hyaluronic acid, pectin and the like. Hydrolysis of these carbohydrates is also carried out by a method using an acidic catalyst such as a strong acid such as sulfuric acid or hydrochloric acid or a weak acid such as oxalic acid, or α-
The method is not particularly limited as long as it is a method of hydrolyzing a carbohydrate such as a method using an enzyme represented by amylase as a catalyst, and a combination thereof. The degree of this hydrolysis may be a water-soluble saccharide having a DE of 10 to 50 or an equivalent molecular weight obtained by hydrolyzing a high molecular weight saccharide, and more preferably D.
E is 15 to 30. In order to obtain a desired composition from these hydrolysates, for example, low molecular weight saccharides obtained by chromatographic separation represented by using a Na ⁺ type ion exchange resin of a styrene-divinylbenzenesulfonic acid copolymer resin or a yeast treatment ( Monosaccharides to trisaccharides), and further the removal of glucose by glucose oxidase treatment.
5% by weight or less of disaccharides, 5 to 25% by weight of trisaccharides, 3 to 15% by weight of 4 sugars, 3 to 20% by weight of 5 sugars, 3 to 25% by weight of hexasaccharides, and 35% by weight of 7 or more sugars % Is not particularly limited as long as it is a method capable of controlling the molecular weight distribution so that the molecular weight becomes not less than%. The saccharide composition thus obtained is purified by a conventional method, and if necessary, concentrated to obtain a solution having a desired concentration. Furthermore, it is possible to dry and store it as a powder for a long time. An aldehyde compound having a carbon-carbon double bond is used as an essential component of the binder of the present invention. As this aldehyde compound, crotonaldehyde, acrolein, or the like can be used. Examples of the type of acidic catalyst required for the crosslinking reaction include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as oxalic acid, benzenesulfonic acid, formic acid, and acetic acid, and the dissociation constant of the acid is Ka = 1 × 10 ^−. There is no particular limitation as long as the acidic catalyst is ⁵ or more. As one of the additives of the present invention, an acid-curable resin such as a water-soluble phenol resin, urea resin, melamine resin and furan resin is used. As the water-soluble phenol resin, a resol-type water-soluble phenol resin can be generally used. These phenolic resins are obtained by condensing phenols and aldehydes in the presence of an alkali or acid catalyst. Examples of phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol F, bisphenol C, bisphenol H, cumylphenol, nonylphenol, isopropenylphenol purified residue, bisphenol A purified residue, bisphenol F purified residue, butylphenol, phenylphenol And phenols including ethyl phenol, octyl phenol, amyl phenol, naphthol, catechol, hydroquinone, pyrogallol, and substituted products thereof.
Aldehydes include, but are not limited to, formalin, paraformaldehyde, α-polyoxymethylene, acetaldehyde, and the like. As a catalyst for condensing these phenols and aldehydes,
Acidic substances such as oxalic acid, hydrochloric acid and sulfuric acid, and organic acid metal salts,
Alternatively, there are hydroxides of alkali metals such as potassium hydroxide, sodium hydroxide, and lithium hydroxide, and hydroxides of alkaline earth metals. Other water-soluble acid-curable resins include urea, methylol urea, dimethylol urea, a urea resin containing dihydroxyethylene urea as a main component, melamine and the above aldehydes obtained by reacting with an alkali or an acid as a catalyst. Melamine resin, furfuryl alcohol resin, furfuryl alcohol / furfural cocondensation resin, furfuryl alcohol / urea cocondensation resin, furfuryl alcohol / phenol cocondensation resin, furfural / phenol cocondensation resin, and the like can be used. These water-soluble phenolic resins, urea resins, melamine resins, and furan resins can be rapidly polymerized by hot air drying or dielectric heating in the presence of an acidic catalyst or by a cross-linking reaction with a water-soluble sugar to improve mold strength,
It is effective in improving the hot strength at the time of pouring, improving the storage stability of the mold by improving the moisture resistance of the mold, and is also effective in preventing decay due to the influence of microorganisms on the binder itself. In addition, polysaccharides, proteins, polyvinyl alcohol,
Water-soluble polymers such as sodium polyacrylate and vinyl acetate resin have a lower solubility in water than water-soluble saccharides, so they dry faster than water-soluble saccharides, and separate after drying to form a strong film. I do. Since this film is more excellent in moisture resistance than the water-soluble saccharide, when added to the oligo binder, the moisture resistance of the mold is improved. The polysaccharide refers to simple or complex polysaccharides of vegetable or animal origin.
For example, starch, modified starch, dextrin, cellulose,
Chemically modified cellulose, dextran, levan, alginates, pectin, hemicellulose, glucomannan,
Galactomannan, vegetable gum, hyaluronic acid and the like.
A protein refers to a vegetable or animal protein containing a peptide. For example, it refers to proteins derived from animals and fungi such as soybean protein, wheat protein, other beans, cereal proteins, casein, albumin, collagen, and hemoglobin. These proteins also include enzymes derived from plants, animals and fungi. The polyvinyl alcohol includes completely saponified, intermediate saponified and partially saponified polyvinyl alcohols, and preferably has a degree of polymerization of about 200 to 3000. Also includes modified polyvinyl alcohol. As the vinyl acetate resin, a solution-type or emulsion-type vinyl acetate resin is preferable, and in some cases, a vinyl acetate resin containing a metal salt such as zinc chloride, aluminum chloride, and zirconyl nitrate and having improved moisture resistance is also included. These auxiliaries can be used in the oligo binder M in an amount of 1 to 30 parts by weight in terms of solids based on 100 parts by weight of the solids. Also,
These auxiliaries can be used by adding them at the time of kneading the oligo binder M and the aggregate without forming a solution in addition to the oligo binder M. In addition, by using a silane coupling agent or a surfactant in combination with the oligo binder M in the present invention, the fluidity of the kneading sand and the strength of the mold can be further improved. As the silane coupling agent, γ-glycidoxypropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, N-glycidyl-N, N-bis (3- (trimethoxysilyl)
Propyl) amine, ureidopropyltriethoxysilane and the like can be used. The above silane coupling agent is preferably added to the oligo binder N in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the solid content. As the surfactant used in the present invention, a nonionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a silicone-based surfactant, a fluorine-based surfactant, and the like can be used. The activator is not particularly limited. These surfactants have the effect of improving the wettability between the binder and the aggregate. The fluidity of the kneading sand when filling the model is also improved. By improving the fluidity, the filling density of the mold is improved, high mold strength is obtained, and a mold having an excellent surface can be obtained. The amount of the surfactant is 0.01 to 5 parts by weight based on 100 parts by weight of the solid content of the oligo binder M.
Parts by weight are preferred.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following Examples,
Various modifications can be made within the scope of the gist. 1. Comparative Evaluation Example in Which Kind of Crosslinking Agent, Addition Amount, and Kind of Acid Catalyst are Changed [Example 1] Corn starch having a water content of 13% is adjusted to be a 30% by weight solid suspension in water. The pH is adjusted to 6.2 using calcium hydroxide. 0.1% by weight of α-amylase (termamamil, manufactured by Novo Nordisk Industries) per starch solid content was added, and 107 ° C.
For 5 minutes to obtain a liquefied starch solution. Furthermore, after treating this liquefied liquid at 90 ° C. for 1 hour, the enzyme reaction is stopped by adding oxalic acid. Decolorization and desalination purification using activated carbon or ion exchange resin is carried out by a conventional method. Then, the mixture was concentrated and dried to obtain a powdery water-soluble sugar. The DE of this water-soluble sugar was 25. 42.5 parts by weight of the above-mentioned water-soluble sugar, 9.2 parts by weight of crotonaldehyde, and 48.3 parts by weight of water were mixed to obtain an oligo-binding agent M shown in Table 1. Next is quartz sand (Iide F-6 No. 6 quartz sand)
4.0 parts by weight of the oligo-binding agent M was added to 100 parts by weight, and a phenolsulfonic acid aqueous solution (solid content: 50%) was added.
0.2% by weight (solid content of oligo binder M 100)
(10 parts by weight with respect to parts by weight) using a kneader to knead the mixture for 60 seconds to obtain a composition for mold making (kneading sand). 10 kneading sand
mm × 10mm × 60mm test piece pressure 29
Blowing at 4 kPa, hot air of air heated to 250 ° C. is sent into the mold at a pressure of 98 kPa, and 5
Suction from the lower part of the mold under reduced pressure of 3.2 kPa,
After that, dry air at room temperature was passed through the mold at a pressure of 98 kPa for 20 seconds, and molded. The bending strength of the obtained mold was measured immediately after molding and after being stored in a thermo-hygrostat (35 ° C., 80%) for 48 hours. Table 2 shows the results. [Example 2] DE = 25 obtained in the same manner as in Example 1.
Is adjusted to be a 35% aqueous solution, and 0.5% by weight of a commercially available dry yeast (Nippon Flour Milling Co., Ltd., Fluffy Pan Dry Yeast) is added to the solid content of the water-soluble sugar. Treat at 36 ° C. with stirring for 3 hours. After deactivating the yeast by boiling, the yeast is subjected to decolorization and desalination purification using activated carbon or an ion exchange resin by a conventional method. Then, the mixture was concentrated and dried to obtain a powdery water-soluble sugar. The DE of this water-soluble saccharide is 19, and its composition is “TSKgel G-Oligo-P” manufactured by Tosoh Corporation.
The analysis was performed by a liquid chromatography apparatus using "W". Its saccharide composition does not include monosaccharides, but contains 1.4% by weight of disaccharides, 13.3% by weight of 3 saccharides, 8.8% by weight of 4 saccharides, 12.6% by weight of 5 saccharides, and 12.6% by weight of hexasaccharides. 15.0% by weight, and 78.9 or more saccharides were 48.9% by weight. 42.5 parts by weight of the above-mentioned water-soluble sugar, 9.2 parts by weight of crotonaldehyde, and 48.3 parts by weight of water were mixed to obtain oligo binder M shown in Table 1. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. [Example 3] DE = 19 obtained in the same manner as in Example 2
42.5 parts by weight of a water-soluble sugar, crotonaldehyde
4 parts by weight of water and 48.3 parts by weight of water were mixed to obtain an oligo binder M shown in Table 1. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. Example 4 DE = 19 obtained in the same manner as in Example 2.
42.5 parts by weight of water-soluble saccharide, crotonaldehyde 9.2
By weight, 48.3 parts by weight of water were mixed to obtain an oligo-binding agent M shown in Table 1. Next is silica sand (Iide F-6 No. 6 silica sand).
4.0 parts by weight of the oligo binder M was added to 0 parts by weight, and 0.5 part by weight of acetic acid (50% by weight of the active ingredient) was further added (based on 100 parts by weight of the solid content of the oligo binder M). 10 parts by weight) using a kneader to knead the mixture for 60 seconds to obtain a mold molding composition (kneaded sand). Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. [Comparative Example 1] DE = 25 obtained in the same manner as in Example 1.
Was mixed with 50.0 parts by weight of water-soluble sugar and 50.0 parts by weight of water to obtain a water-soluble binder. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. [Comparative Example 2] DE = 19 obtained in the same manner as in Example 2.
Was mixed with 50.0 parts by weight of water-soluble sugar and 50.0 parts by weight of water to obtain a water-soluble binder. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. [Comparative Example 3] 50.0 parts by weight of anhydrous crystalline glucose, water 5
0.0 parts by weight were mixed to obtain a water-soluble binder. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. [Comparative Example 4] A water-soluble sugar having a DE of 7 (Sanwa Starch Co., Ltd.)
Manufactured by Sundeck # 70) and 50.0 parts by weight of water to obtain a water-soluble binder. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. Comparative Example 5 42.5 parts by weight of anhydrous crystalline glucose, 9.2 parts by weight of crotonaldehyde, and 48.3 parts by weight of water were mixed to obtain a water-soluble binder. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results. [Comparative Example 6] DE = 19 obtained in the same manner as in Example 2.
17.5 parts by weight of a water-soluble sugar, glutaraldehyde
5 parts by weight and 50.0 parts by weight of water were mixed to obtain an oligo binder M shown in Table 1. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 2 shows the results.

Table 1 Properties of oligo binder M and comparative binders (Notes 1 and 2) (Types of cross-linking agent and types of acidic catalyst) Note 1. The solid content concentration of all binders was 50% by weight. Note2. The drying and curing treatment method was performed under a pressure of 250 ° C. Air. Note3. Shows the amount of binder added to 100 parts by weight of solids.

[Table 2] Temporal change of mold strength 2. Comparative Evaluation Example in which Various Additives were Added to Oligo Binder M [Example 6] DE = 19 obtained in the same manner as in Example 2
36.1 parts by weight of water-soluble sugar, crotonaldehyde 6.4
Parts by weight, water-soluble resol type phenol resin (PL-4746 (50% by weight of solid content), manufactured by Gunei Chemical Industry Co., Ltd.) 1
5.0 parts by weight and 42.5 parts by weight of water were mixed to obtain oligo binder M shown in Table 3. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results. Example 7 DE = 19 obtained in the same manner as in Example 2.
36.1 parts by weight of water-soluble sugar, crotonaldehyde 6.4
By weight, 7.5 parts by weight of soybean peptide protein (manufactured by Fuji Oil Co., Ltd., Hynute) and 50 parts by weight of water were mixed to obtain oligo binder M shown in Table 3. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results. Example 8 DE = 19 obtained in the same manner as in Example 2.
42.1 parts by weight of a water-soluble sugar of crotonaldehyde 7.4
Parts by weight, silane coupling agent (Nihon Unicar Co., Ltd.)
(A-1100), 0.5 parts by weight of water and 50.0 parts by weight of water to obtain an oligo binder M shown in Table 3. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results. Example 9 DE = 19 obtained in the same manner as in Example 2.
42.2 parts by weight of a water-soluble sugar of crotonaldehyde 7.5
Parts by weight, fluorinated surfactant (manufactured by Sumitomo 3M Co., Ltd., FC
-129) 0.3 parts by weight of water and 50.0 parts by weight of water are mixed,
An oligo binder M shown in Table 3 was obtained. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results. [Example 10] DE = 1 obtained in the same manner as in Example 2
34.6 parts by weight of water-soluble sugar of No. 9, crotonaldehyde 6.
1 part by weight, water-soluble resol type phenol resin (PL-4746 (50% by weight solid content), manufactured by Gunei Chemical Industry Co., Ltd.)
10.0 parts by weight, casein (manufactured by Nissei Kyoeki Co., Ltd.) 3.5
Parts by weight, silane coupling agent (Nihon Unicar Co., Ltd.)
A-1100), 0.5 parts by weight of a fluorosurfactant (FC-129, manufactured by Sumitomo 3M Limited), and 45.0 parts by weight of water. A binder M was obtained. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results. [Comparative Example 7] DE = 19 obtained in the same manner as in Example 2.
42.5 parts by weight of a water-soluble sugar, 15.0 parts by weight of a water-soluble resol type phenol resin (PL-4746 (solid content: 50% by weight) manufactured by Gunei Chemical Industry Co., Ltd.) and 42.5 parts by weight of water After mixing, a water-soluble binder was obtained. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results. [Comparative Example 8] DE = 19 obtained in the same manner as in Example 2.
42.5 parts by weight of water-soluble sugar, 7.5 parts by weight of soybean peptide protein (manufactured by Fuji Oil Co., Ltd., Hynute), and 50.0 parts of water
The parts by weight were mixed to obtain a water-soluble binder. Example 1 below
A mold was formed in the same manner as described above, and the bending strength was measured.
Table 4 shows the results. [Comparative Example 9] DE = 19 obtained in the same manner as in Example 2.
49.5 parts by weight of a water-soluble sugar, 0.5 part by weight of a silane coupling agent (A-1100, manufactured by Nippon Unicar Co., Ltd.) and 50.0 parts by weight of water are mixed to obtain a water-soluble binder. Was. Thereafter, a mold was formed in the same manner as in Example 1, and the bending strength was measured. Table 4 shows the results.

Table 3 Properties of oligo binder M and comparative binder (Notes 1, 2, 3, 4) (Addition of acid-curable resin, auxiliary agent, silane coupling agent, surfactant) Note 1. The solid content concentration of all binders was 50% by weight. Note2. The binder in the examples has a solids ratio of oligosaccharide: crotonaldehyde = 85: 15. Note3. The binder in the examples contains 10 parts by weight of phenolsulfonic acid per 100 parts by weight of oligo binder. Note4. The drying and curing treatment method was performed under a pressure of 250 ° C. Air. Note5. The numerical values indicate the combined parts by weight based on 100 parts by weight of the solid content of the oligo binder M.

[Table 4] Temporal change of mold strength 3. Oligo Binder M and Comparative Example Comparative Evaluation Example by Changing Drying Method of Binder [Example 11] Oligo binder M obtained in the same manner as in Example 10 was treated with silica sand (Iideyo F- No. 6 silica sand) 4.0 parts by weight were added to 100 parts by weight, and 0.2 parts by weight of a phenolsulfonic acid aqueous solution (solid content: 50% by weight) was further added, and the mixture was kneaded with a kneader for 60 seconds to form a mold. A composition (kneading sand) was obtained. The kneaded sand is blown into a 10 mm × 10 mm × 60 mm TP mold at a pressure of 294 kPa, and hot air of N ₂ heated to 250 ° C. is sent into the mold at a pressure of 98 kPa, and from the bottom of the mold at a reduced pressure of 53.2 kPa. Suction was performed and drying was performed for 2 minutes. Finally, dry air at room temperature was passed through the mold at a pressure of 98 kPa for 20 seconds to mold. Immediately after molding of the obtained mold, and in a thermo-hygrostat (35 ° C, 80%)
After storing for 8 hours, the bending strength was measured. Table 6 shows the results
Shown in Example 12 A mold composition obtained in the same manner as in Example 11 was blown into a 10 mm × 10 mm × 60 mm TP mold at a pressure of 294 kPa, and air at 25 ° C. was applied at a pressure of 1
Drying is performed by ventilating the mold at 96 kPa to 3
Performed for minutes and molded. The bending strength of the obtained mold was measured immediately after molding and after being stored in a thermo-hygrostat (35 ° C., 80%) for 48 hours. Table 6 shows the results. Example 13 A mold composition obtained in the same manner as in Example 11 was put into a 10 mm × 10 mm × 60 mm TP mold, and was then carried into a vertical vacuum box as shown in FIG.
The pressure in the vacuum box was set to 0.8 kPa and held for 3 minutes.
Immediately after molding of the obtained mold and in a thermo-hygrostat (35 ° C., 8
0%) for 48 hours, and the bending strength was measured. In addition, the odor was evaluated at the time of molding and at the time of removing the mold. Table 6 shows the results. Example 14 The mold composition obtained in the same manner as in Example 11 was put into a 10 mm × 10 mm × 60 mm TP mold, and then was carried into a vertical vacuum box as shown in FIG.
The pressure inside the vacuum box was kept at 48.0 kPa for 15 minutes. Immediately after molding of the obtained mold, and in a thermo-hygrostat (35
(80 ° C., 80%) for 48 hours, and the bending strength was measured. In addition, the odor was evaluated at the time of molding and at the time of removing the mold. Table 6 shows the results. Comparative Example 10 A mold composition obtained in the same manner as in Example 11 was blown into a 10 mm × 10 mm × 60 mm TP mold at a pressure of 294 kPa, and hot air of air heated to 450 ° C. was molded at a pressure of 98 kPa. Inside and
Suction was performed from the lower part of the mold under a reduced pressure of 53.2 kPa, and drying was performed for 1 minute. Finally, dry air at room temperature was passed through the mold at a pressure of 98 kPa for 20 seconds to mold. The bending strength of the obtained mold was measured immediately after molding and after being stored in a thermo-hygrostat (35 ° C., 80%) for 48 hours. The odor was evaluated at the time of molding and at the time of removing the mold. Table 6 shows the results. [Comparative Example 11] The mold composition obtained in the same manner as in Example 11 was put into a 10 mm x 10 mm x 60 mm TP mold, and then was carried into a vertical vacuum box as shown in FIG.
The pressure in the vacuum box was kept at 60.0 kPa for 20 minutes. Immediately after molding of the obtained mold, and in a thermo-hygrostat (35
(80 ° C., 80%) for 48 hours, and the bending strength was measured. In addition, the odor was evaluated at the time of molding and at the time of removing the mold. Table 6 shows the results.

[Table 5] Drying method for oligo binder M and comparative binder (Note 6) Note6. All binders used are the same as in Example 10 in Table 3.

[Table 6] Temporal change of mold strength

According to the present invention described in detail above, a water-soluble saccharide, particularly a water-soluble saccharide having a restricted saccharide composition, an aldehyde having a double bond and a binder containing an acidic catalyst as essential components. By using a water-soluble saccharide binder containing a water-soluble acid-curable resin, an auxiliary agent, a silane coupling agent and a surfactant, a mold for obtaining a mold having high strength and excellent moisture resistance can be obtained. Compositions can be provided. Further, according to the present invention, it is possible to provide a mold molding method capable of obtaining a high-strength mold in a short time by using the above-described composition for mold molding using a drying gas and drying under reduced pressure.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a method of placing a mold in a closed container and vacuum-drying the same in the mold making method of the present invention.

FIG. 2 is an explanatory view showing another example of a method of vacuum-drying by placing a mold in a closed container in the mold making method of the present invention.

FIG. 3 is an explanatory view showing still another example of a method of placing a mold in a closed container and drying in a vacuum in the mold making method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed container (vacuum box) 2 Mold 3 Perforated plate 4 Airtight flexible membrane

Continuation of the front page (72) Inventor Akihiro Okubo 700, Shukudaidaicho, Takasaki City, Gunma Prefecture Gunei Chemical Industry Co., Ltd.

Claims (30)

[Claims] 1. An aggregate of at least one of silica sand, zircon sand, olivine sand, chromite sand, alumina sand, and mullite sand, and natural oligosaccharides and / or A water-soluble saccharide having a dextrose equivalent of 10 to 50 obtained by hydrolyzing starch or a water-soluble saccharide having a molecular weight equivalent to the starch hydrolyzate obtained by hydrolyzing a natural high molecular weight saccharide, and a carbon-carbon double bond Wherein the weight ratio of solids thereof is water-soluble saccharide: aldehyde compound = 50: 50-99: 1,
Further, 0.5 to 10 parts by weight of a water-soluble binder having a solid content concentration of 20 to 75% by weight and an acid dissociation constant of Ka
= 1 × 10 ^-5 or more inorganic acids or for mold formation composition that features can be obtained by mixing 0.1 to 25 parts by weight added to 100 parts by weight of solid content of an organic acid wherein the binder . 2. The saccharide composition in the binder is 1% by weight or less in terms of solid content of monosaccharides, 5% by weight or less of disaccharides, 5 to 25% by weight of trisaccharides, and 3 to 15% of tetrasaccharides. 3% by weight pentasaccharide
The composition for mold making according to claim 1, wherein the composition is a water-soluble saccharide of -20% by weight, 6-25% by weight of hexasaccharide, and 35% by weight or more of saccharides. 3. A binder comprising at least one of a water-soluble phenol resin, a urea resin, a melamine resin and a furan resin in a solid content of 1 to 50 parts by weight per 100 parts by weight of the binder solid content. The composition for mold making according to claim 1 or 2, wherein the composition comprises parts by weight. 4. A binder comprising at least one of a polysaccharide, a protein, polyvinyl alcohol, sodium polyacrylate and a vinyl acetate resin as an adjuvant with respect to 100 parts by weight of the solid content of the binder. The composition for mold making according to any one of claims 1 to 3, wherein the composition comprises 1 to 30 parts by weight in terms of solid content. 5. The binder according to claim 1, wherein the binder contains 0.1 to 5 parts by weight of a silane coupling agent based on 100 parts by weight of the solid content of the binder. Item 2. The composition for mold making according to Item 1. 6. The binder according to claim 1, wherein the binder contains 0.01 to 5 parts by weight of a surfactant based on 100 parts by weight of the solid content of the binder. Item 10. The composition for mold making according to item 8. 7. One or more aggregates of silica sand, zircon sand, olivine sand, chromite sand, alumina sand, and mullite sand, and natural oligosaccharides and / or A water-soluble saccharide having a dextrose equivalent of 10 to 50 obtained by hydrolyzing starch or a water-soluble saccharide having a molecular weight equivalent to the starch hydrolyzate obtained by hydrolyzing a natural high molecular weight saccharide, and a carbon-carbon double bond Wherein the weight ratio of solids thereof is water-soluble saccharide: aldehyde compound = 50: 50-99: 1,
Further, 0.5 to 10 parts by weight of a water-soluble binder having a solid content concentration of 20 to 75% by weight and an acid dissociation constant of Ka
= 1 × 10 ⁻⁵ or more of an inorganic acid or an organic acid is added to 0.1 to 25 parts by weight based on 100 parts by weight of the solid content of the binder, and the resulting mixture is mixed with a mold for molding. And then forcibly air, CO ₂ , He, Ne, Ar,
And casting mold making method characterized by drying cured at one or more dry gas N _2. 8. The saccharide composition in the binder is 1% by weight or less in terms of solid content of monosaccharides, 5% by weight or less of disaccharides, 5 to 25% by weight of trisaccharides, 3 to 15% by weight of tetrasaccharides. 3% by weight pentasaccharide
The method according to claim 7, wherein the water-soluble saccharide is -20% by weight, hexasaccharides are 3-25% by weight, and 7 or more saccharides are 35% by weight or more. 9. A water-soluble phenol resin, a urea resin, and a binder, based on 100 parts by weight of a solid content of the binder.
9. The method according to claim 7, wherein at least one of melamine resin and furan resin is contained in an amount of 1 to 50 parts by weight in terms of solid content. 10. The binder has a solid content of 100%.
10. The composition according to claim 7, wherein at least one of polysaccharides, proteins, polyvinyl alcohol, sodium polyacrylate, and vinyl acetate resin is contained as a supplement in an amount of 1 to 30 parts by weight as solids. The method of molding a mold according to any one of the above items. 11. The binder according to claim 1, wherein the binder has a solid content of 100.
The silane coupling agent is contained in an amount of 0.1 to 5 parts by weight based on part by weight.
The molding method according to the above item. 12. The binder according to claim 1, wherein the binder has a solid content of 100.
The method according to any one of claims 7 to 11, wherein the surfactant is contained in an amount of 0.01 to 5 parts by weight with respect to part by weight. 13. An aggregate of at least one of silica sand, zircon sand, olivine sand, chromite sand, alumina sand, and mullite sand, and natural oligosaccharides and / or A water-soluble saccharide having a dextrose equivalent of 10 to 50 obtained by hydrolyzing starch or a water-soluble saccharide having a molecular weight equivalent to the starch hydrolyzate obtained by hydrolyzing a natural high molecular weight saccharide, and a carbon-carbon double bond Which have a solid content weight ratio of water-soluble saccharide: aldehyde compound = 50: 50-99: 1 and a solid content concentration of 20-75% by weight of water-soluble caking. 0.5 to 10 parts by weight of an agent and 0.1 to 25 parts by weight of an inorganic or organic acid having a dissociation constant of Ka = 1 × 10 ⁻⁵ or more based on 100 parts by weight of the solid content of the binder Casting obtained by adding and mixing The molding composition, in a method of forcibly dried and cured after filling in the mold model, pressure temperature 0 ° C. to 80 ° C. in a dry gas into said model from 4.9 to 3
A method for molding a mold, characterized in that aeration is performed at 90 kPa, or suction is performed at a reduced pressure of 1.33 to 101 kPa simultaneously with aeration at the above pressure. 14. The saccharide composition in the binder is 1% by weight or less in terms of solid content of monosaccharides, 5% by weight or less of disaccharides, 5 to 25% by weight of trisaccharides, 3 to 15% by weight of tetrasaccharides. 14. The method according to claim 13, wherein the water-soluble saccharide is 3 to 20% by weight of a pentasaccharide, 3 to 25% by weight of a hexasaccharide, and 35% by weight or more of 7 or more saccharides. 15. The binder according to claim 15, wherein the binder has a solid content of 100.
The method according to claim 13, wherein at least one of a water-soluble phenol resin, a urea resin, a melamine resin, and a furan resin is contained in an amount of 1 to 50 parts by weight on a solid basis with respect to parts by weight. . 16. The binder has a solid content of 100%.
16. The composition according to claim 13, wherein at least one of a polysaccharide, a protein, polyvinyl alcohol, sodium polyacrylate, and a vinyl acetate resin is contained as a supplement in an amount of 1 to 30 parts by weight as solids. The method of molding a mold according to any one of the above items. 17. A method according to claim 17, wherein the binder has a solid content of 100.
The composition for mold making according to any one of claims 13 to 16, wherein the composition contains 0.1 to 5 parts by weight of a silane coupling agent with respect to part by weight. 18. The binder according to claim 1, wherein the binder has a solid content of 100.
The method according to any one of claims 13 to 17, wherein the surfactant is contained in an amount of 0.01 to 5 parts by weight based on part by weight. 19. One or more aggregates of silica sand, zircon sand, olivine sand, chromite sand, alumina sand, and mullite sand, and natural oligosaccharides and / or A water-soluble saccharide having a dextrose equivalent of 10 to 50 obtained by hydrolyzing starch or a water-soluble saccharide having a molecular weight equivalent to the starch hydrolyzate obtained by hydrolyzing a natural high molecular weight saccharide, and a carbon-carbon double bond Which have a solid content weight ratio of water-soluble saccharide: aldehyde compound = 50: 50-99: 1 and a solid content concentration of 20-75% by weight of water-soluble caking. 0.5 to 10 parts by weight of an agent and 0.1 to 25 parts by weight of an inorganic or organic acid having a dissociation constant of Ka = 1 × 10 ⁻⁵ or more based on 100 parts by weight of the solid content of the binder Casting obtained by adding and mixing The molding composition, in a method of forcibly dried and cured after filling in the mold model, pressure drying gas temperature 80 to 400 ° C. in 該模 the type 4.9 to 3
Aerating at 90 kPa, or at the same time as aeration at a reduced pressure of 1.33 to 101 kPa, followed by aerating a dry gas at a temperature of 50 ° C. or less at the pressure and quenching. Method. 20. The saccharide composition in the binder according to claim 1, wherein the monosaccharide is 1% by weight or less in terms of solids, the disaccharide is 5% by weight or less, the trisaccharide is 5 to 25% by weight, and the tetrasaccharide is 3 to 15%. 20. The method according to claim 19, wherein the water-soluble saccharide is 3 to 20% by weight of a pentasaccharide, 3 to 25% by weight of a hexasaccharide, and 35% by weight or more of 7 or more saccharides. 21. A binder having a solid content of 100
21. The mold molding method according to claim 19, wherein at least one of a water-soluble phenol resin, a urea resin, a melamine resin, and a furan resin is contained in an amount of 1 to 50 parts by weight on a solid basis with respect to parts by weight. . 22. The binder according to claim 1, wherein the binder has a solid content of 100.
22. The composition according to claim 19, wherein at least one of a polysaccharide, a protein, polyvinyl alcohol, sodium polyacrylate and a vinyl acetate resin is contained in an amount of 1 to 30 parts by weight as a solid content with respect to parts by weight. The method of molding a mold according to any one of the above items. 23. A binder having a solid content of 100
The composition for mold making according to any one of claims 19 to 22, comprising 0.1 to 5 parts by weight of a silane coupling agent with respect to part by weight. 24. The binder according to claim 1, wherein the binder has a solid content of 100.
The method according to any one of claims 19 to 23, wherein the surfactant is contained in an amount of 0.01 to 5 parts by weight with respect to part by weight. 25. One or more aggregates of silica sand, zircon sand, olivine sand, chromite sand, alumina sand, and mullite sand, and natural oligosaccharides and / or A water-soluble saccharide having a dextrose equivalent of 10 to 50 obtained by hydrolyzing starch or a water-soluble saccharide having a molecular weight equivalent to the starch hydrolyzate obtained by hydrolyzing a natural high molecular weight saccharide, and a carbon-carbon double bond Which have a solid content weight ratio of water-soluble saccharide: aldehyde compound = 50: 50-99: 1 and a solid content concentration of 20-75% by weight of water-soluble caking. 0.5 to 10 parts by weight of an agent and 0.1 to 25 parts by weight of an inorganic or organic acid having a dissociation constant of Ka = 1 × 10 ⁻⁵ or more based on 100 parts by weight of the solid content of the binder Casting obtained by adding and mixing In a method of forcibly drying and curing the molding composition after filling it into a mold model, after placing the molding composition in a closed container, the pressure in the container is maintained at 48.0 kPa or less, A mold molding method characterized by forcibly removing moisture in a mold and drying and curing. 26. The saccharide composition in the binder according to the present invention is such that monosaccharides are 1% by weight or less in terms of solid content, 2 saccharides are 5% by weight or less, 3 saccharides are 5 to 25% by weight, and 4 saccharides are 3 to 15%. 26. The method according to claim 25, wherein the water-soluble saccharide is 3 to 20% by weight of pentasaccharide, 3 to 25% by weight of hexasaccharide, and 35% by weight or more of 7 or more saccharides. 27. The binder according to claim 1, wherein the binder has a solid content of 100.
27. The method of claim 25 or 26, wherein at least one of a water-soluble phenol resin, a urea resin, a melamine resin, and a furan resin is contained in an amount of 1 to 50 parts by weight on a solid basis with respect to parts by weight. . 28. A method according to claim 28, wherein the binder has a solid content of 100.
28. The composition according to claim 25, wherein at least one of a polysaccharide, a protein, polyvinyl alcohol, sodium polyacrylate and a vinyl acetate resin is contained as a supplement in an amount of 1 to 30 parts by weight as solids. The method of molding a mold according to any one of the above items. 29. The binder according to claim 1, wherein the binder has a solid content of 100.
The composition for mold making according to any one of claims 25 to 28, comprising 0.1 to 5 parts by weight of a silane coupling agent with respect to part by weight. 30. A binder having a solid content of 100
The method according to any one of claims 25 to 29, wherein the surfactant is contained in an amount of 0.01 to 5 parts by weight based on part by weight.