JP2002028750A - Organic binder for casting mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic binder for producing a phenol urethane base gas-curing mold or a self-curing type mold used in a sand mold casting. SOLUTION: This organic binder contains an organic solvent soluble phenol resin, a polyisocyanate compound and a polybutadien as the indispensable components, and a functional group polybutadien which has the functional group at both ends of molecule, having at least one kind of the functional group selected among groups of a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group, an amino group, an amide group and an ester group, in the organic solvent soluble phenol resin, the polyisocyanate compound and molecule, as the indispensable components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic binder for producing a phenolurethane-based gas-curing mold or a self-hardening mold used in sand casting.

[0002]

2. Description of the Related Art A phenol urethane-based mold (hereinafter referred to as "mold"), which is one of the typical organic molds used in sand casting, includes a phenol resin and a polyisocyanate compound which do not require heating during molding. 2. Description of the Related Art Mass production type gas curing molds manufactured by a cold box method using an addition reaction and non-mass production type self-hardening molds manufactured by a normal temperature self-hardening method are widely known. For example, a mold by the cold box method is usually prepared by mixing a granular refractory aggregate (hereinafter simply referred to as “aggregate”) with an organic binder comprising a phenol resin solution and a polyisocyanate solution using an organic solvent as a solvent. A mold material was prepared by mixing and coating the surface of the aggregate with the binder, and was blown into a mold to form a mold.Then, an amine-based catalyst gas was passed through the mold to mold the mold. It is manufactured by a method of curing.

[0003]

However, a mold using this kind of mold material has a molding trouble in which a part of the mold adheres to the mold surface when the cured mold is removed from the mold. Since the phenomenon of "staining" tends to occur, it is difficult to obtain a casting having a beautiful casting surface by casting using a mold having no smooth surface. For this reason, when "staining" is likely to occur on the mold, it is necessary to apply a release agent every time or frequently clean the mold, so that the production cost increases and the productivity decreases. Therefore, there is a strong demand for improvement of "sticking" to the mold.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has the physical properties such as bending strength required for a mold used in sand casting and improved "sticking" to a mold. An object of the present invention is to provide an organic binder for producing a phenol urethane-based mold such as a cured mold or a self-hardening mold.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, by mixing a polybutadiene compound into a mold material, the molding of the mold has been performed without impairing physical properties such as strength. The inventors have found that "staining" on a mold can be significantly improved, and based on this finding, have completed the present invention. That is, the present invention is an organic binder for a mold, comprising an organic solvent-soluble phenol resin, a polyisocyanate compound and polybutadiene as essential components. Another aspect of the present invention is an organic binder for a mold, comprising, as essential components, an organic solvent-soluble phenol resin, a polyisocyanate compound, and a functional polybutadiene having a functional group in a molecule.

The phenolic resin used in the present invention is an organic solvent-soluble benzyl ether type phenol resin, a resol type phenolic resin, a novolak type phenolic resin obtained by adding and condensing phenols and aldehydes (preferably formaldehyde). Phenolic resins and their modified phenolic resins and mixtures thereof. From the viewpoints of lowering the viscosity, compatibility with the polyisocyanate component, coating properties on the aggregate, and the properties of the mold, these resins generally contain an active ingredient containing a combination of a polar organic solvent and a non-polar organic solvent as a solvent. Is prepared as a solution of about 40 to 80% by mass and used as a phenol resin component (A) of an organic binder. Examples of the organic solvent used herein include aromatic hydrocarbons, halogenated hydrocarbons, ketones, esters, ethers, aliphatic hydrocarbons, and alicyclic hydrocarbons. Examples of the phenol resin modifier include cashew oil, rosin, and xylene resin. The phenolic resin component (A) may further include a silane compound such as 3-glycidoxypropyltrimethoxysilane and isophthalic acid as a pot life extender in order to improve the adhesiveness between the resin component and the aggregate, if necessary. In addition to the acid chloride represented by acid chloride, a deterioration inhibitor, an anti-drying agent, a release agent and the like can be added.

The polyisocyanate compound used in the present invention is a polyisocyanate compound having two or more isocyanate groups in a molecule for causing a polyaddition reaction with the active hydrogen of the phenol resin to develop a chemical bond between aggregates. is there. Specific examples of such polyisocyanate compounds include polyisocyanates represented by aromatic, aliphatic or alicyclic compounds, such as diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate (hereinafter referred to as “polymeric MDI”), hexamethylene diisocyanate, In addition to 4'-dicyclohexylmethane diisocyanate, prepolymers having isocyanate groups obtained by reacting these polyisocyanate compounds with polyols can be mentioned.
These may be used alone or in combination of two or more. For the same reason as the phenolic resin component (A), these polyisocyanate compounds are also prepared as a solution having a non-polar organic solvent or a combination of the non-polar organic solvent and a polar organic solvent with an active ingredient amount of about 40 to 90% by mass. However, in some cases, it is used in the form of a stock solution. The polyisocyanate component (B) thus prepared
And an organic binder comprising the phenolic resin component (A) and the phenolic resin component (A).
The amount is usually 0.01 to 10 parts by mass, preferably 0.1 to 5.0 parts by mass with respect to 00 parts by mass.

The polybutadiene and / or functional polybutadiene (hereinafter referred to as “polybutadiene-based compound”) used in the present invention plays a role in suppressing the “sticking” of a mold to a mold. 1,2-polybutadiene having an unsaturated double bond in the molecule obtained by polymerizing butadiene;
A butadiene polymer such as polybutadiene, and a functional polybutadiene are functional polybutadienes having a functional group in the molecule of the butadiene polymer. This is superior to polybutadiene in terms of the effect of suppressing "staining". Among them, a telechelic functional polybutadiene having functional groups at both molecular terminals is particularly preferable. Examples of the functional group include, but are not limited to, a hydroxyl group, a carboxyl group, a glycidyl group, an isocyanate group, an amino group, an amide group, an ester group, an acryl group, a maleic anhydride residue, a halogen group, and a nitrile group. It is not something to be done. Above all, from the viewpoint of the effect of suppressing "staining",
A hydroxyl group, a carboxyl group, a glycidyl group, an isocyanate group, an amino group, an amide group and an ester group are preferred. These functional groups are more preferably introduced in the molecule, particularly at both ends, in the same or different kind.

Specific examples of the polybutadiene include, for example, trade names: B700, B1000, manufactured by Nippon Petrochemical Co., Ltd.
Nippon Soda's trade name: B1000 and the like. Specific examples of the functional polybutadiene include, for example, trade name: M1000-2 (functional group is maleic anhydride residue), E700-3.5 (functional group is glycidyl group), manufactured by Nippon Petrochemical Co., Ltd., manufactured by Nippon Soda Co., Ltd. Trade name: C1000 (functional group is carboxyl group), G1000 (functional group is hydroxyl group), EP
B-13 (functional group is glycidyl group), TEA1000
(Functional group is acrylic group), trade name: R, manufactured by Idemitsu Petrochemical Co., Ltd.
15HT and R45HT (functional group is hydroxyl group), HTP
9 (functional group is an isocyanate group) and the like,
It is not limited to these. These may be used alone or in combination of two or more. Among such polybutadiene compounds, the number average molecular weight measured by gel permeation chromatography is 200 to 50,000, preferably 500 to 10,000, more preferably 500 to 500 in terms of polystyrene.
0 and a liquid polybutadiene compound at 25 ° C. are preferred. When the number average molecular weight is less than 200, the effect of suppressing "staining" is small, and conversely, the number average molecular weight is 5,000.
If it exceeds 0, the coating property on the aggregate will be reduced.
The number average molecular weight is measured by gel permeation chromatography manufactured by Tosoh Corporation. ◇ Standard polystyrene: TSK-standard polystyrene ◇ Equipment: SC-8020 カ ラ ム Column: TSK-Gel G2000H _XL + TSK
-Gel G4000H _XL ◇ Eluent: tetrahydrofuran (elution rate 1.0 ml /
Min) ◇ Detection conditions: RI detector

The above-mentioned polybutadiene compound is usually used in an amount of 0.001 to 100 parts by mass based on the total amount of the active ingredients of the phenol resin component (A) and the polyisocyanate component (B).
20 parts by mass, preferably 0.01 to 10 parts by mass. If the amount is less than 0.001 part by mass, the effect of suppressing "staining" is small, and if it exceeds 20 parts by mass, the mold strength is reduced.

[0011] The mold material for a cold box using the organic binder of the present invention is usually composed of a phenolic resin component (A) and a polyisocyanate component (B) as an organic binder, and a polybutadiene-based component as an inhibitor component for "staining". It is produced by thoroughly kneading the compound and the aggregate with a mixer, preferably at a temperature in the range of -10 to 50C.
The mold material used for room-temperature self-hardening is produced by mixing a curing catalyst such as a base, an amine, or a metal ion during mixing. At this time, the polybutadiene-based compound is prepared separately from a phenol resin solution and a polyisocyanate solution in advance, and the polybutadiene-based compound is added to one or both of them, or a solution of the polybutadiene-based compound is separately prepared. It may be added at the time of kneading together with the solution. Next, the obtained mold material is shaped into a mold by a cold box method or a normal temperature self-hardening method, and then subjected to casting. Examples of the aggregate herein include special sands such as silica sand, oripin sand, zircon sand, chromite sand, and alumina sand; slag-based particles such as ferrochrome-based slag, ferronickel-based slag, and converter slag; ), Regenerated sands thereof, and mixtures thereof.

[0012]

The reason why the organic binder of the present invention improves the adhesion of the mold to the mold during molding of the mold (so-called soaking) as compared with the conventional organic binder is not clear, but is as follows. Inferred to. That is, the polybutadiene-based compound, which is one component of the binder, has a different affinity for the phenolic resin and the polyisocyanate compound, so that phase separation easily occurs, and a polybutadiene cured film is formed by the reaction between the mold and the mold. Since it is formed, the load when the mold is released from the mold is small, and it is possible to prevent the mold from being caught on the mold side. In addition, the functionalized polybutadiene having a functional group forms a cured film having a release agent effect on the mold surface by polymerizing it, and a chemical interaction between the functional group and the metal surface causes the mold to move from the mold to the mold. It is presumed that the film does not easily peel off from the mold even when the mold is removed, and the release agent effect is maintained.

[0013]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In addition, “part” means “part by mass”.

Example 1 As a phenol resin component (A) of an organic binder, 50 parts of a benzyl ether type phenol resin, 20 parts of a fatty acid methyl ester mixture, IP150 (trade name: petroleum solvent,
A phenol resin solution comprising 30 parts of Idemitsu Petrochemical Co., Ltd.) and 0.3 part of 3-glycidoxypropyltrimethoxysilane was prepared. On the other hand, as a polyisocyanate component (B), 75 parts of polymeric MDI,
A polyisocyanate solution consisting of 25 parts 150 and 0.3 parts isophthalic chloride was prepared.

[0015] Next, 10 silver white silica sand No. 6 (trade name, manufactured by Sanei Silica) was used as an aggregate in a laboratory-type river mixer.
0 parts, 0.9 parts each of a phenolic resin component (A) and a polyisocyanate component (B) as an organic binder, and C1000 as a functional polybutadiene (trade name, liquid polybutadiene having a carboxyl group as a functional group,
After adding 0.0045 parts (manufactured by Nippon Soda Co., Ltd.), the mixture was kneaded for 40 seconds to prepare a mold material 1.

Examples 2 to 9 In Example 1, the functional polybutadiene (trade name: C
The mold materials 2 to 9 were prepared in the same manner as in Example 1 except that the addition amount was changed to 1000) and the amount of the functional polybutadiene or polybutadiene shown in Table 1 was added.

Comparative Example 1 The procedure of Example 1 was repeated except that the polybutadiene compound was not used and the addition amount was changed as shown in Table 1.
A template material for comparison was prepared in the same manner as described above.

Next, the mold materials prepared in Examples 1 to 9 and Comparative Example 1 and the mold material for comparison were measured for the bending strength (N / cm ² ) immediately after the removal by the following test method, The evaluation of "stickiness" was performed. Table 1 shows the results. 1. Measurement of bending strength immediately after removal of the mold After placing the mold material in the sand magazine of the cold box molding machine, the mold material was blow-filled with a gauge pressure of 0.3 MPa into the test piece preparation mold, and the test piece for bending strength measurement ( 10
^H mm × 30 ^W mm × 80 ^L mm), and then triethylamine gas was introduced into the mold at a gauge pressure of 0.05 MPa.
After gassing for 1 second at 10 MPa at a gauge pressure of 0.3 MPa
A test piece was prepared by air purging for 2 seconds and removing the mold. The bending strength of the prepared test piece was measured immediately, and this was defined as the punching strength (N / cm ² ). 2. Evaluation of Stainability After the mold material was placed in a sand magazine of a cold box molding machine, a blow port 2 having a diameter of 10 mm was provided at the upper part shown in FIG.
The mold material is charged at a blow pressure of 0.4 MPa into a test mold 3 in which a metal piece 1 for evaluating "stainability" weighed in advance at the bottom is detachably buried, and triethylamine gas is charged at a gauge pressure of 0.4 MPa. Gassing for 1 second at 05MPa, air purge for 15 seconds at a gauge pressure of 0.1MPa and test mold 3
Was removed from the mold. Next, the above operation was repeated 10 times without removing the stain on the surface of the metal plate, and then the metal piece 1 was removed from the test mold 3 and weighed. (Mg), and the larger the value, the worse the “staining property”.

[0019]

[Table 1]

As is clear from Table 1, the organic binder of the present invention impairs physical properties such as strength required for casting by using a polybutadiene compound, particularly a functional polybutadiene having a functional group introduced into the molecule. Without "stickiness"
Was significantly improved.

[0021]

The organic binder for a mold according to the present invention, which uses a polybutadiene and / or a functional polybutadiene, does not impair the physical properties such as strength, and has a phenol resin component and a polyisocyanate component as essential components. Since the disadvantage of the organic binder of the present invention, that is, the sticking of the mold to the mold surface, so-called "staining", can be remarkably reduced, troubles in the releasability are greatly improved. For this reason, it is possible to reduce the application of the release agent and the cleaning of the mold as in the related art, thereby improving the production cost and productivity.
Moreover, such a mold that is manufactured efficiently and economically and has a smooth surface can provide a casting with a beautiful casting surface.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a molding die for evaluating adhesion.

[Explanation of symbols]

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

Claims (4)

[Claims] 1. An organic binder for a mold comprising, as essential components, an organic solvent-soluble phenol resin, a polyisocyanate compound and polybutadiene. 2. An organic binder for a mold comprising, as essential components, an organic solvent-soluble phenol resin, a polyisocyanate compound and a functional polybutadiene having a functional group in a molecule. 3. The organic binder for a template according to claim 2, wherein the functional polybutadiene has a functional group at both molecular terminals. 4. The organic binder according to claim 2, wherein the functional group is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group, an amino group, an amide group and an ester group. .