JP2003181594A - Mold release agent for urethane casting mold, its manufacturing method, organic caking additive made by using the mold release agent and casting mold material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold release agent for a urethane casting mold effective to suppress stickers to the forming casting mold without impairing casting mold strength and to provide a method for manufacturing the same, an organic caking additive containing the mold release agent and a casting mold material. <P>SOLUTION: The mold release agent for the urethane casting mold contains a modified polybutadiene having a phenolic hydroxyl group at both or one end of a molecule as indispensable ingredient. The method for manufacturing the mold release agent for the urethane casting mold comprises a step of manufacturing the modified butadiene having isocyanate groups at both or one end of a molecule by reacting the polybutadiene having the alcoholic hydroxide groups at both ends of the molecule with a polyisocyanate compound, and a step of manufacturing the modified polybutadiene having phenolic hydroxide groups at both or one end of the molecule by reacting the modified polybutadiene obtained in the previous step with a compound having two or more phenolic nuclei in a molecule. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a urethane-based mold release agent effective for improving mold release troubles when molding a urethane-based mold (main mold, core) used in sand mold casting, and a method for producing the same. And an organic binder and a mold material using the release agent.

[0002]

2. Description of the Related Art A typical urethane mold used in sand mold casting is an energy-saving type that does not require heating utilizing the reaction of an organic solvent-soluble phenolic resin and a polyisocyanate compound in the presence of a curing catalyst at room temperature. 2. Description of the Related Art A gas hardening mold that is mass-produced by a mold making method, such as a cold box method, and a self-hardening mold that is non-massively manufactured by a room-temperature self-hardening method are widely known. In particular, the cold box method has recently been emphasized as a competitive technology of the shell mold method.

This cold box method uses a granular refractory aggregate and a two-component organic binder (phenolic resin organic solvent solution and polyisocyanate compound or its organic solvent solution).
And kneading in a mixer to produce a granular refractory aggregate coated with an organic binder, that is, a mold material, which is blow-filled in a mold and then aerated with an amine-based curing catalyst. This is a method of molding a gas curing mold (hereinafter referred to as a mold) by curing the mold material in the molding die in a short time.

[0004]

However, in this type of mold material, when the cured mold is taken out of the mold, the cured particles of the mold material or a part of the mold adheres to the mold surface and becomes rough on the mold surface. Phenomenon that causes a defect in the mold
Generally, a mold release trouble called "staining" is likely to occur. Naturally, it is difficult to obtain a casting with a beautiful casting surface by casting using a mold lacking such surface smoothness, and if there is a large defect, it is discarded as a defective mold. For this reason, at the molding site, it is inevitable to apply a mold release agent every time to a place where stains are likely to occur, or to perform frequent cleaning, which results in an increase in production cost and a decrease in productivity. ing. Under these circumstances, there is a strong demand in the technical field to improve the clinging property of the mold material to the mold.

The present invention has been made in order to overcome the mold release trouble caused by the above-mentioned clinging phenomenon.
It is an object of the invention to provide a urethane-based mold release agent for a mold, which is effective in suppressing the clinging property of the mold material to the mold without deteriorating the mold strength. A second object is to provide an organic solvent solution of a phenol resin and a urethane-based mold release agent that is not separated from the organic solvent solution. A third object is to provide a method for producing the release agent. Further, a fourth and a fifth object are such an organic mold release agent for urethane-type molds, and an organic binder for urethane-type molds and a urethane-type mold which contain fatty acid monoester useful as an essential component for improving the working environment. The purpose is to provide a casting mold material.

[0006]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventor has found that by using a specific modified polybutadiene, the clinging property of a mold material to a mold can be obtained without impairing the mold strength. The present invention was completed by further research based on this finding.

That is, in the present invention, a modified polybutadiene having a phenolic hydroxyl group at both ends or one end of the molecule, preferably a higher fatty acid having 10 or more carbon atoms and / or an unsaturated fatty acid modified alkyd resin is an essential component. It is a release agent for urethane type molds characterized by the above.

Another aspect of the present invention is to produce a modified polybutadiene having isocyanate groups at both ends or one end of the molecule by reacting polybutadiene having alcoholic hydroxyl groups at both ends of the molecule with a polyisocyanate compound. A step of reacting the modified polybutadiene obtained in the step with a compound having two or more phenol nuclei in the molecule, preferably bisphenol A, to produce a modified polybutadiene having a phenolic hydroxyl group at both ends or one end of the molecule. The method for producing a urethane-based mold release agent for a mold as described above, characterized by comprising:

In another aspect of the present invention, a phenol resin component, a polyisocyanate component and the above-mentioned releasing agent are used as essential components, or a fatty acid monoester is used as an organic solvent for at least one of these components. It is an organic binder for urethane type molds, which is characterized in that

Still another aspect of the present invention is a mold material for urethane type molds, which comprises the above organic binder as an essential component.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The urethane-based mold release agent for a mold according to the present invention (hereinafter referred to as a release agent component) is mainly described in 2 below.
A compound or an organic solvent solution thereof having a releasing ability effective for suppressing clinging to a mold of a mold material produced using a liquid organic binder (phenol resin component and polyisocyanate component), Specifically, modified polybutadiene having a phenolic hydroxyl group at both ends or one end of the molecule (hereinafter, simply referred to as phenol modified polybutadiene), preferably a phenolic hydroxyl group at both ends which is advantageous in terms of solubility in an organic solvent. A modified polybutadiene having
Or these phenol-modified polybutadiene and carbon number 1
It is a combination with 0 or more higher fatty acid and / or unsaturated fatty acid-modified alkyd resin.

This phenol-modified polybutadiene is prepared by first reacting a polybutadiene having an alcoholic hydroxyl group at both ends of the molecule (hereinafter, simply referred to as alcohol-modified polybutadiene) with a polyisocyanate compound to form an isocyanate group at both ends or one end of the molecule. It is produced by preparing a modified polybutadiene having and then reacting the isocyanate modified polybutadiene with a compound having two or more phenol nuclei in the molecule. The reaction is not particularly limited, but is generally 20 to 10 using no catalyst and, if necessary, a reaction catalyst such as lead naphthenate.
1-10 at a temperature of 0 ° C., preferably in the presence of an organic solvent.
It will take about an hour.

When the number average molecular weight of the alcohol-modified polybutadiene applied to the above reaction is less than 200, the effect of suppressing the clinging property is small, and conversely, when it exceeds 50,000, the coating property on the granular refractory aggregate is deteriorated. Since there is a tendency, those in the range of 200 to 50,000 are usually used. Further, when considering the solubility in an organic solvent, the number average molecular weight is preferably in the range of 500 to 10,000, more preferably in the range of 500 to 5,000. Preferable specific examples of the alcohol-modified polybutadiene include G1000 (trade name, manufactured by Nippon Petrochemical Co., Ltd.), R15HT and R45HT (both are trade names, manufactured by Idemitsu Petrochemical Co., Ltd.). It is not limited. These may be used alone or in combination of two or more.

The number average molecular weight of the alcohol-modified polybutadiene is a polystyrene conversion value measured by gel permeation chromatography and can be measured under the following conditions. ◇ Standard polystyrene: TSK-standard polystyrene ◇ Device: SC-8020 ◇ Column packing: TSK-Gel G2000H _XL +
TSK-Gel G4000H _XL ◇ Eluent: tetrahydrofuran (elution rate 1.0 ml /
Min) ◇ Detection condition: RI detector

Next, in the above reaction, the polyisocyanate compound is a combination of an alcohol-modified polybutadiene having a releasing ability and a compound having two or more phenol nuclei in the molecule described below, which has an ability to improve solubility in an organic solvent. A compound having a function, and examples of such a polyisocyanate compound include aromatic polyisocyanates such as diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate (hereinafter referred to as polymeric MDI), aliphatic polyisocyanates such as hexamethylene diisocyanate, Examples include alicyclic polyisocyanates such as 4,4′-dicyclohexylmethane diisocyanate and prepolymers having an isocyanate group obtained by reacting these polyisocyanates with polyols. It is, but is not limited thereto. These may be used alone or in combination of two or more.

Among the polyisocyanate compounds,
Aromatic polyisocyanates, particularly diphenylmethane diisocyanate, are preferred from the viewpoint of improving the solubility in organic solvents. The compounding amount of the polyisocyanate compound is not particularly limited, but considering the remarkable increase of the molecular weight and the production of by-products, it is preferable that the isocyanate group of the polyisocyanate compound is 1 mol of the alcoholic hydroxyl group of the alcohol-modified polybutadiene. 1.5 ~
It is 3.5 mol, and particularly preferably 2.0 to 3.0 mol.

Next, a compound having two or more phenol nuclei in the molecule (hereinafter referred to as polyphenol compound) is
As mentioned above, it is a compound which improves the solubility of the alcohol-modified polybutadiene in the organic solvent by reacting with the modified polybutadiene having isocyanate groups at both ends or one end of the molecule prepared by the pre-reaction. Examples of such compounds include bisphenols such as bisphenol F and bisphenol A, phenol oligomers such as trisphenol and tetraphenol, novolac type, resol type, and benzyl ether type phenol resins. These may be used alone or in combination of two or more.

Among these polyphenol compounds, bisphenol is preferable from the viewpoint of solubility in organic solvents and cost, and bisphenol A is particularly preferable. The amount of such a polyphenolic compound is not particularly limited, but considering that the presence of excess unreacted compound may adversely affect the template strength depending on its type, preferably the polyisocyanate compound used in the pre-reaction is The amount of the phenolic hydroxyl group contained in the polyphenol compound is 1.0 to 1.2 mol based on 1 mol of the isocyanate group contained.

The thus obtained phenol-modified polybutadiene is generally used by dissolving it in the phenol resin component described below or as a solution in an organic solvent. Has the advantage that no separation of
The organic solvent solution of phenol-modified polybutadiene is used together with the phenol resin component and the polyisocyanate component when preparing the template material.

This phenol-modified polybutadiene is used in an amount of 0.1 parts by weight based on 100 parts by weight of the total amount of the phenol resin component and the polyisocyanate component added to the granular refractory aggregate.
It is used in a proportion of 001 to 20 parts by mass, preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass. If the amount used is less than 0.001 part by mass, the effect of suppressing clinging is small, and if it exceeds 20 parts by mass, the mold strength tends to decrease.

The phenol-modified polybutadiene has a higher fatty acid having 10 or more carbon atoms, for example, saturated fatty acid (for example, myristic acid, palmitic acid, stearic acid, etc.), unsaturated fatty acid (for example, oleic acid, etc.) for further anti-staining effect. Linoleic acid, linolenic acid, etc.) and mixtures containing unsaturated fatty acids as main components (eg tall oil fatty acids, linseed oil fatty acids, etc.) and / or unsaturated fatty acid modified alkyd resins (eg modifiers: tall oil fatty acids, linseed oil fatty acids) Etc.) is preferably used together. Among the higher fatty acids, a mixture containing unsaturated fatty acid or unsaturated fatty acid as a main component, which has high solubility in an organic solvent and is difficult to separate even at low temperature, has a wide range of storage and use conditions of the product, but the latter mixture is particularly preferable. preferable.

This higher fatty acid and / or unsaturated fatty acid-modified alkyd resin is used in a proportion of 0.01 to 5 parts by mass with respect to 100 parts by mass of the phenol resin component. If the amount used is less than 0.01 part by mass, the combined effect is not observed, and conversely, if it exceeds 5 parts by mass, the mold strength tends to decrease significantly.

The organic binder according to the present invention is crosslinked and hardened at room temperature in the presence of a hardening catalyst such as metal ions and triethylamine to bond the granular refractory aggregates to develop strength, and at the same time, to form the template material. A binder capable of suppressing clinging to a molding die, wherein at least a phenol resin component, a polyisocyanate component, and the urethane-based mold release agent (release agent component) are essential components,
It is configured.

This phenol resin component is generally made of the following phenol resin in combination with a polar organic solvent and a non-polar organic solvent from the viewpoints of low viscosity, compatibility with polyisocyanate component, coatability on granular refractory aggregate, mold strength and the like. It is prepared by using a combination solvent with an organic solvent to prepare a solution of about 40 to 80% by mass and used. In addition, the phenol resin component may include a silane coupling agent such as 3-glycidoxypropyltrimethoxysilane as a strength improver, a carboxylic acid chloride typified by isophthalic acid chloride as a pot life extender, and a strength improver. Phosphonic acid chloride, phosphonyl chloride and the like can be added.

As the phenol resin, an organic solvent-soluble phenol resin (for example, benzyl ether type phenol resin, obtained by reacting phenols and aldehydes in the presence of an acidic divalent metal salt, an acidic catalyst and a basic catalyst). Examples thereof include, but are not limited to, a resol type phenol resin and a novolac type phenol resin), a modified phenol resin obtained by reacting or mixing a modifier during or after the production of the phenol resin, and a mixture thereof.

Examples of the phenols mentioned here include alkylphenols such as phenol, cresol, xylenol and p-tert-butylphenol, bisphenols such as bisphenol F and bisphenol A, and mixtures thereof. Examples of aldehydes include formalin, paraformaldehyde, polyoxymethylene, and mixtures thereof.
Examples of the modifier include alkyd resin, xylene resin, epoxy compound, polyvinyl alcohol, urea, amides, linseed oil, cashew oil, rosin, and mixtures thereof.

Examples of the organic solvent include ketones such as isophorone, dibasic acid esters such as dibasic acid methyl ester mixture, vegetable oil methyl esters such as soybean oil methyl ester, methyl linolenate and butyl stearate. Esters such as fatty acid monoesters, ethers such as isopropyl ether, polar organic solvents such as furfuryl alcohol and, for example, Ipsol 150 (trade name, petroleum solvent manufactured by Idemitsu Petroleum Co., Ltd.), Shoishi Hisol (trade name, Non-polar organic solvents such as Showa Shell Sekiyu Co., Ltd. petroleum solvent) are exemplified. Among them, JP-A-9-253786 and JP-A-2000-84
The fatty acid monoester described in Japanese Patent No. 643 is useful for substituting or reducing the nonpolar organic solvent from the viewpoint of environmental problems.

On the other hand, the polyisocyanate component is preferably a polyisocyanate compound described above from the viewpoints of generally lowering the viscosity, compatibility with the phenol resin component, coating property on the granular refractory aggregate, mold strength and the like. It is generally used by preparing a solution of about 40 to 90% by mass with a polar organic solvent, but in some cases, it is also used as a stock solution. Specific examples of such a polyisocyanate compound include the polyisocyanate compounds listed in the above-mentioned production of the phenol-modified polybutadiene.

The mold material according to the present invention preferably comprises, for example, a granular refractory aggregate; an organic binder containing a phenol resin component, a polyisocyanate component and a release agent component as essential components and, if necessary, a curing catalyst. It is produced by sufficiently kneading with a mixer at an aggregate temperature of about ℃. Then, the obtained mold material, for example, a mold material containing a curing agent, is filled in a molding die, filled while being vibrated in some cases, and left standing at room temperature for about several hours to 24 hours to be cured at room temperature. Or by the cold box method as described above. At this time, the phenol resin component and the polyisocyanate component are each usually 0.01 to 5.0 parts by mass, preferably 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the granular refractory aggregate. Used in proportion.

Examples of the granular refractory aggregates used herein include special sands such as silica sand, olivine sand, zircon sand, chromite sand and alumina sand, slags such as ferrochrome slag, ferronickel slag and converter slag. Examples thereof include particles, mullite-based artificial particles such as nigai cera beads (trade name), and recovered sand and / or reclaimed sand thereof. These may be used alone or 2
You may use it in combination of 2 or more types.

[0031]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. "Parts" and "%" are all "mass parts"
And "mass%".

Example 1 <Preparation of Release Agent for Urethane Mold> As alcohol-modified polybutadiene in a reaction flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube,
Polybutadiene having alcoholic hydroxyl groups at both ends of the molecule (trade name R15HT manufactured by Idemitsu Petrochemical Co., Ltd., number average molecular weight 1200, hydroxyl group content 1.83 mol / 100)
18 parts, diphenylmethane diisocyanate as a polyisocyanate compound (trade name: Cosmonate PH, manufactured by Mitsui Chemicals, Inc., isocyanate group content: 33.
(5% by mass) was added, and the mixture was reacted under stirring in a nitrogen atmosphere at 80 ° C. for 3 hours to obtain a modified polybutadiene having isocyanate groups at both ends of the molecule.
Next, dibasic acid methyl ester mixture (dimethyl succinate: dimethyl glutarate: dimethyl adipate = 25
Part: 55 parts: 20 parts) 60 parts and 1 part of bisphenol A
After adding 1 part, homogenize by stirring in a nitrogen atmosphere, then add 0.0085 parts of lead naphthenate and react at 50 ° C. for 1 hour to make modified polybutadiene having phenolic hydroxyl groups at both ends of the molecule (phenol-modified polybutadiene). A solution having a content of 40%, that is, an organic solvent solution of a so-called urethane-based mold release agent was obtained.

<Preparation of Organic Binder A> 50 parts of benzyl ether type phenol resin manufactured by Asahi Organic Materials Co., Ltd., which is a constituent of phenol resin component, 17 parts of dibasic acid methyl ester mixture, 28 parts of petroleum solvent and 0.3 parts of 3-glycidoxypropyltrimethoxysilane and 5 parts of the 40% phenol-modified polybutadiene solution as the release agent component are mixed by stirring to mix the release agent-containing phenol resin component (a-
1) was prepared. The releasing agent-containing phenol resin component (a-1) was composed of 98% of the phenol resin component and 2% of the phenol-modified polybutadiene, and the phenol-modified polybutadiene was not separated even after standing for 6 months after the preparation. In addition, the polyisocyanate component (b-
1) is a polymeric MDI as a polyisocyanate compound (trade name: Cosmonate M20 manufactured by Mitsui Chemicals, Inc.)
0) 75 parts, 25 parts of petroleum solvent and 0.3 part of isophthalic acid chloride were mixed by stirring to prepare. These two components {(a-1) and (b-1)} were set as an organic binder A.

<Preparation of mold material and its evaluation> Laboratory supplies 100 parts of Sanei No. 6 silica sand and the above-mentioned organic binder A, that is, a releasing agent-containing phenol resin component (a-) in a river mixer
0.9 parts of each of 1) and the polyisocyanate component (b-1) were added and then kneaded for 40 seconds to prepare a template material A. With respect to the obtained mold material, the mold strength was measured immediately after the mold was removed and the clinging property was evaluated by the following test method. The results are shown in Table 1.

1. Measurement of Mold Strength Immediately after Demolding After the mold material was placed in the sand magazine of the cold box molding machine, it was placed in the mold for making the mold strength test piece.
Blow filling was performed with a gauge pressure of 3 MPa. Next, in the mold, a triethylamine gas generator was used to generate 0.0
Triethylamine was gassed for 1 second with a gauge pressure of 5 MPa, air-purged with a gauge pressure of 0.3 MPa for 10 seconds, and then die-cut to obtain a bending strength test piece (width 30 mm x length 80 mm).
× thickness 10 mm) was produced. The bending strength of the obtained test piece was immediately measured by a shell mold bending strength tester (manufactured by Tohoku Seimitsu Co., Ltd.), and the bending strength (N /
cm ² ).

2. Measurement of Stainability After the mold material was put into the sand magazine of the cold box molding machine, the test mold 3 shown in FIG.
Of which the mold material is removably embedded in the bottom portion and has a pre-weighed metal piece 1 for evaluation of clinging property) is filled with a mold material at a blow pressure of 0.4 MPa, and triethylamine gas is added at a gauge pressure of 0. Gassing at 05 MPa for 1 second, air purging at a gauge pressure of 0.1 MPa for 15 seconds, and then removing the mold from the test mold 3 While repeating the molding operation, the metal from the test mold 3 was removed every 5, 10, 15 and 20 times. The piece 1 was removed and weighed, and the difference in mass between the metal piece 1 before and after the test was taken as the amount of clinging (mg). The larger the value, the poorer the clinging property, that is, the poorer the releasability.

Example 2 To 100.3 parts of the release agent-containing phenol resin component (a-1) prepared in exactly the same manner as in Example 1, 1.5 parts of tall oil fatty acid as a higher fatty acid was added and mixed. The obtained release agent-containing phenol resin component (a-2) and the polyisocyanate component (b-1) described in Example 1 were set as an organic binder B. The release agent-containing phenol resin component (a-2) is 96.5% phenol resin component,
It was composed of 2.0% of phenol-modified polybutadiene and 1.5% of tall oil fatty acid, and no separation of phenol-modified polybutadiene and tall oil fatty acid was observed even after standing for 6 months after preparation. Further, in the same manner as in Example 1, a template material B made of the organic binder B was prepared. With respect to the obtained mold material, the mold strength immediately after the mold was removed and the clinging property were evaluated by the test method described in Example 1. The results are shown in Table 1.

Example 3 First, 55 parts of a benzyl ether type phenol resin which is a constituent of a phenol resin component, 20 parts of a dibasic acid methyl ester mixture, 20 parts of soybean oil methyl ester and 3-
0.3 parts of glycidoxypropyltrimethoxysilane,
A release agent-containing phenol resin component (a-3) was prepared by stirring and mixing 5 parts of a 40% phenol-modified polybutadiene solution as a release agent component and 1.5 parts of tall oil fatty acid. The releasing agent-containing phenol resin component (a-3) was composed of 96.5% phenol resin component, 2.0% phenol-modified polybutadiene and 1.5% tall oil fatty acid, and left for 6 months after adjustment. However, no separation of phenol-modified polybutadiene and tall oil fatty acid was observed. The polyisocyanate component (b-2) was prepared by stirring and mixing 85 parts of polymeric MDI as a polyisocyanate compound, 15 parts of soybean oil methyl ester and 0.3 part of isophthalic acid chloride. These two components {(a-3) and (b-2)} were set to be an organic binder C.

Next, in the same manner as in Example 1, the organic binder C
A template material C according to was produced. With respect to the obtained mold material, as a result of measuring the mold strength immediately after mold release and evaluating the clinging property according to the test method described in Example 1, soybean oil methyl ester has performance comparable to petroleum-based solvents. It was confirmed. The results are shown in Table 1.

Comparative Example 1 First, 50 parts of a benzyl ether type phenol resin, 22 parts of a dibasic acid methyl ester mixture, 28 parts of a petroleum solvent and 0.3-glycidoxypropyltrimethoxysilane.
Phenol resin component (a-4) obtained by stirring and mixing parts
And the polyisocyanate component (b-
1) and was set as an organic binder D. Next, in the same manner as in Example 1, a template material D was prepared using the organic binder D. With respect to the obtained mold material, the mold strength immediately after the mold was removed and the clinging property were evaluated by the test method described in Example 1. The results are shown in Table 1.

Comparative Example 2 100.3 parts of a phenol resin component (a-4) prepared in exactly the same manner as in Comparative Example 1 was further added with tall oil fatty acid 1.
A release agent-containing phenol resin component (a-5) obtained by adding and mixing 5 parts and the polyisocyanate component (b-1) described in Example 1 were set as an organic binder E. The releasing agent-containing phenol resin component (a-5) consisted of 98.5% phenol resin component and 1.5% tall oil fatty acid, and separation of tall oil fatty acid was observed even after 6 months of preparation. There wasn't. Next, in the same manner as in Example 1, a template material E was prepared using the organic binder E. With respect to the obtained mold material, the mold strength immediately after the mold was removed and the clinging property were evaluated by the test method described in Example 1. The results are shown in Table 1.

[0042]

[Table 1]

[0043]

As described above, the urethane-based mold release agent for a mold, the organic binder and the mold material according to the present invention have the following effects. 1. The urethane-based mold release agent according to the present invention can significantly improve the clinging property of the mold material to the mold without deteriorating the mold strength, and can be easily dissolved in the organic solvent solution of the phenol resin. Therefore, it is possible to provide remarkably high convenience such that the mold material can be easily manufactured by the existing kneading equipment without providing a new mold release agent adding equipment. 2. In the organic binder according to the present invention, since a phenol resin component containing a urethane-based mold release agent having excellent dissolution stability that does not separate from an organic solvent solution of a phenol resin is used, a stable mold release ability is exhibited, It can contribute to stabilization of the molding process. In addition, since the fatty acid monoester has a performance comparable to that of petroleum-based solvents, it can contribute to the improvement of working environment by using it as an alternative solvent. 3. Since the mold material according to the present invention can greatly improve the clinging property to the mold during molding without impairing the mold strength, it is necessary to apply a mold release agent and clean the mold as in the conventional case. In addition, it is possible to improve the production cost and productivity, such as reducing molding defects. Further, since the surface of the obtained mold is smooth, it is possible to provide a casting having a beautiful casting surface.

[Brief description of drawings]

FIG. 1 is a side sectional view of a mold for producing a test piece for measuring stainability.

[Explanation of symbols]

1 ... Metal piece 2 ... Blow mouth 3 ... Test mold

Claims (7)

[Claims] 1. A urethane-based mold releasing agent for molds, which comprises a modified polybutadiene having a phenolic hydroxyl group at both ends or one end of the molecule as an essential component. 2. The urethane-based mold releasing agent according to claim 1, further comprising a higher fatty acid and / or unsaturated fatty acid-modified alkyd resin having 10 or more carbon atoms as an essential component. 3. A process of reacting polybutadiene having an alcoholic hydroxyl group at both ends of the molecule with a polyisocyanate compound to produce a modified polybutadiene having an isocyanate group at both ends or one end of the molecule, and a step obtained in the process. And a step of reacting the modified polybutadiene with a compound having two or more phenol nuclei in the molecule to produce a modified polybutadiene having a phenolic hydroxyl group at both ends or one end of the molecule. 2. The method for producing a urethane mold release agent according to 2. 4. The method for producing a urethane mold release agent according to claim 3, wherein the compound having two or more phenol nuclei in the molecule is bisphenol A. 5. An organic binder for a urethane-based template, which comprises a phenol resin component, a polyisocyanate component and the release agent according to claim 1 or 2 as essential constituent components. 6. An organic binder for a urethane-based template, characterized in that a fatty acid monoester is used as an organic solvent for at least one component according to claim 5. 7. A mold material for urethane-type molds, which comprises the organic binder according to claim 5 or 6 as an essential component.