JPS5913543A - Composition of resin coated sand and its production - Google Patents

Abstract

PURPOSE:To accelerate the collapsing property of a casting mold after charging molten metal by using sand grains for casting, which are coated with a phenolic resin incorporated with an arom. nitro compd., in forming the casting mold for casting low m.p. metals. CONSTITUTION:A casting mold formed by using the sand grains which are coated with a resin produced by adding 0.2-40pts.wt. arom. nitro compd. to 100pts.wt. phenolic resin is used in the stage of casting metals having lower m.p. as compared to iron, for example, Al and Mg. The arom. nitro compd. is o-, p- or m-nitrophenol, 2.4, 2.5 or 2.6 dinitrophenol, and dinitronaphthalene and the phenolic resin is novolak type, resol type or their mixed resins, and is further preferably incorporated therein with a lubricant such as ethylene-bis-stearamide. Then, the collapsion of the casting mold takes place at about 300-400 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a resin-coated sand composition for casting a metal having a lower melting point than iron, such as aluminum or magnesium, and a method for producing the same. related.

Recently, in order to reduce the weight of automobile casting parts, Confucian,
Instead of traditional iron, light metals such as aluminum and magnesium are used, and these materials have low melting points.

It is expected that casting of these light metals will become increasingly popular in the future.

On the other hand, when casting a resin-coated sand mold (
In order to conserve resources, a method has been adopted in which the shell mold is treated and the sand is recovered, and then this sand is reused for casting (2) to improve the sand yield as much as possible.

In the case of iron-based metals, the internal temperature of the shell mold during pouring is 8.
Since the temperature is between 00 and 1000℃, the phenolic resin used as a binder is exposed to high temperatures and is almost thermally decomposed (secondarily, the strength of the shell mold after pouring naturally decreases). Therefore, after casting, the shell core is in the form of sand and can be easily removed from the casting, but when casting low melting point metals such as aluminum or magnesium, the internal temperature of the shell mold during pouring is low. 300~b For this reason, the decomposition of the phenolic resin in the shell mold is insufficient, and since the shell mold maintains sufficient strength, it is possible to take out the shell core more efficiently than from the casting in complex casting shapes. Therefore, in such cases, the cast shell core should be removed by making it into a sandy state (2). We have to find a way to break it down.

This means that when producing large quantities of aluminum castings,
This has become a major obstacle to improving productivity and saving energy.

Next (Details of the second invention will be described.

To promote the disintegration of shell molds when pouring metals with low melting points such as aluminum, the chemical trivalent crosslinking structure that occurs after curing of the phenolic resin used as a binder is a methylene group, a methine group. , dimethylene ether group, etc. Among these crosslinked structures, the dimethylene ether group changes to a methylene group by heating (2).On the other hand, both methylene and methine groups are thermally decomposed (2), so they require high energy to decompose because they are stable. do.

Therefore, one method for making the thermal decomposition of phenolic resins occur at a low temperature of 300 to 400°C is the activation of heat (oxidative thermal decomposition of bistable methylene groups and mejy groups).
It is thought that adding a substance that has a tactile effect that reduces energy is effective.

After casting a low melting point metal such as aluminum, the inventors
In order to promote the disintegration of shell molds, as a result of intensive research into substances that provide the above-mentioned catalytic effect, we found that the presence of aromatic nitrides in corded sand, in which foundry sand grains are coated with phenolic resin (Second, note) It has been found that the disintegration of the shell mold after hot water is extremely promoted.

The aromatic nitrate of the present invention is 0 citrophenol, p-
=) Lophenol, m-w Trophenol, 2.4
Dinitrophenol, 2.5 dinitrophenol,
2.6 dinitrophenol, dinitronaphthalene, etc. One or more of these aromatic nitrides are combined with 4J, 4
It can be used for six purposes.

The blending ratio of the aromatic nitrate of the present invention to the phenol resin is 0.2 to 100 parts (2 parts) of the phenol resin.
A range of 40 parts by weight is optimal. 0 aromatic nitrides
．． If the amount is less than 2 parts by weight, the effect of promoting the disintegration of the shell mold will be poor, and if it exceeds 40 parts by weight, the properties such as strength and hardenability of the obtained shell mold will decrease.

The aromatic nitrate can be blended into the phenol resin at any time during the production of the phenol resin, at the start of the reaction between phenol and pornoaldehyde, during the reaction, or after the reaction is completed.

Alternatively, 1. After the production of the phenol resin, the phenol resin and the aromatic nitrate may be mixed by pulverization and dispersed, or kneaded using an extruder or the like (or melt-mixed using a second method).

Additionally, an aromatic nitrate may be added during the manufacturing process of the resin-coated sand composition.

Timing of addition during the manufacturing process of the resin-coated sand composition) It is possible to add it before, after, or simultaneously with the addition of the phenol resin.

Further, the aromatic nitrate may be blended as it is or after being dispersed or dissolved in a medium.

Regardless of the blending method, the disintegration properties of shell molds produced from the resulting resin-coated sand composition are significantly promoted.

As the phenolic resin used in the present invention, any of a mixture of a novolac type resin and a resol type resin and a novolac type resin and a resol type resin can be used.

Phenols used as raw materials during the production of the phenolic resin of the present invention include phenol, cresol, xylenol, etc., and those in which resorcinol, catechol, hydroquinone, aniline, urea, melamine, cashew naratonel oil, etc. are present. can also be used. Formaldehyde is formalin, rose formaldehyde,
Aldehyde materials selected from trioxane and the like can be used.

In addition, the reaction catalyst for novolac type resin is general (=, oxalic acid,
Acidic substances such as hydrochloric acid and sulfuric acid, and metal salts of organic acids.

As reaction catalysts for resol type resins, general basic substances such as ammonia, triethylamine, sodium hydroxide, and barium hydroxide are used.

As the lubricant for carrying out the present invention, ordinary lubricants can be used, but ethylene bisstearamide, methylenebinustearamide, oxinstearamide, stearamide, and methylolstearamide are preferable.

Furthermore, even if this lubricant is added at any time during the production of the phenol resin, before the start of the reaction, during the reaction, and after the completion of the reaction, a phenol resin containing the lubricant can be produced.

The method for producing the resin-coated sand composition employed in the present invention may be any of the dry hot coating method, semi-hot coating method, cold coating method, and powder solvent method. 2. Preferably, a dry hot coating method is recommended for implementation.

The present invention will be explained below using Example C2. However, the present invention is not limited to these Example C2.

In addition, the "part" and 1 part described in each example and comparative example.
%" indicates 1 part by weight J and "% by weight."

Production Example 1.2 Two reaction vessels equipped with a cooler and a stirrer were prepared, and 1000 parts of phenol, 650 parts of 37% formalin, and then 10 parts of oxalic acid were charged into each of them. The temperature gradually rises to 96
After refluxing for 120 minutes after reaching the temperature, 10 parts of methylene bisstearamide, further (-2,4 dinitrophenol and dinitronaphthalene) were added to the reaction vessel (21 parts).
100 parts of each seed was added. After mixing and dispersing, a dehydration reaction was performed under vacuum and the mixture was taken out of the pot. The blending amount of the zero-aromatic nitrate to obtain 1070 parts of each novolac type phenolic resin was 10 parts each based on 100 parts of the novolak type phenolic resin.

Production Example 3.4 Two reaction vessels equipped with a cooler and a stirrer were prepared, and 1000 parts of phenol, 1795 parts of 37% formalin, and
Next, 160 parts of 28% aqueous ammonia and 90 parts of 50% aqueous sodium hydroxide solution were added. The temperature was gradually raised until the temperature reached 96°C (==). After the addition and reflux reaction, 40 parts of methylene bisstearamide, 2.4 dinitrophenol, and dinitronaphthalene were added to the reaction vessel, one each. After mixing and dispersing the mixture, a dehydration reaction was carried out under vacuum, and the mixture was taken out of the pot and rapidly cooled. 1320 parts of each resol type phenolic resin were obtained.
The blending amount of each aromatic nitrate was 20 parts per 100 parts of the resol type phenol resin.

Production Example 5.6 Two reaction vessels with a cooler and a stirrer were prepared, and each of them was
1000 parts of nibenol, 650 parts of 37% formalin,
Next, 10 parts of oxalic acid was charged. The temperature gradually increases until the temperature reaches 9
After reaching 6°C, the mixture was refluxed for 30 minutes, and then 0 parts and 485 parts of methylene, 10 parts of stearamide, and 2.4 parts of dinitrophenol (=2.4) were added to the reaction vessel.The mixture was mixed and dispersed. After that, a dehydration reaction was carried out under vacuum and the pot was taken out.

970 parts each of novolak type phenolic resin, 145 parts
The blending amount of the obtained 5 parts of the zero aromatic nitrate was 100 parts of the novolac type phenolic resin (0 parts and 50 parts for the two, respectively).

Production Example 7 A reaction vessel with a cooler and a stirrer was prepared, and this (=1000 parts of phenol, 1795 parts of 37% polymerin, then 2
160 parts of 8% aqueous ammonia and 60 parts of 50% aqueous sodium hydroxide solution were added. The mouth temperature gradually rose to 96℃ (
After two consecutive reflux reactions for 30 minutes, 40 parts of methylene bisstearamide was added, a dehydration reaction was carried out under vacuum, and the mixture was taken out of the pot and rapidly cooled. Resol type phenolic resin 1
I got 100 copies.

Example 1 Sanei No. 6 silica sand 7000 heated to a temperature of 130-140°C
After adding 140 parts of the novolak type phenolic resin obtained in Production Example 1 to a whirl mixer (= charging, 4 parts
The mixture was kneaded for 0 seconds.

Next, 21 parts of hexamethylenetetramine was dissolved in 105 parts of water and mixed and kneaded until the coated sand disintegrated.Furthermore, 7 parts of calcium stearate was added, mixed for 30 seconds, and the sand was drained to perform air layering. A resin coated sand composition was obtained.

Example 2 A resin-coated sand composition was obtained under the same manufacturing conditions as in Example 1 except that the novolac type phenolic resin obtained in Production Example 2 was used.

Example 3 Temperature: 130-140°C (-heated Sanei No. 6 silica sand 700
0 part was placed in a Whirl mixer, 140 parts of the resol type phenolic resin obtained in Production Example 3 was added, and after kneading for 40 seconds, 105 parts of cooling water was added and kneaded until the resin coated sand collapsed. 7 parts of calcium stearate was added, mixed for 30 seconds, and the sand was removed and aerated to obtain a resin coated sand composition.

Example 4 Production conditions were the same as in Example 3 except that the resol type phenolic resin obtained in Production Example 4 was used (a resin-coated sand composition was obtained).

Example 5 Sanei No. 6 silica sand 70 heated to a temperature of 130 to 140'C1
00 parts were placed in a Whirl mixer, and 130 parts of the novolak type phenol resin obtained in Production Example 5 (2) were added thereto and kneaded for 20 seconds. Then, 13 parts of 2.4 dinitrophenol was added and kneaded for 20 seconds. 21 parts of hexamethylenetetramine dissolved in 105 parts of water was added and kneaded until the resin coated sand collapsed.

Then, 7 parts of calcium stearate was added, mixed for 30 seconds, and air layered to obtain a resin-coated sand composition.

Example 6 Sanei No. 6 silica sand 7000 heated to 130-140°C
1 part was placed in a Whirl mixer, 13 parts of 2,4 dinitrophenol was added thereto, and the mixture was kneaded for 20 seconds.

Next, 78 parts of the novolac type phenolic resin obtained in Production Example 5 (2) and 52 parts of the resol type phenolic resin obtained in Production Example 7 (2) were added and kneaded for 20 seconds.

Furthermore, 13 parts of hexamethylenetetramine dissolved in 63 parts of water was added, and the mixture was kneaded until the resin-coated sand collapsed.

Then, 7 parts of calcium stearate was added, mixed for 9 seconds, and the sand was removed and air layered to obtain a resin coated sand composition.

Comparative Example 1 Sanei No. 6 silica sand 7000 heated to a temperature of 130-140°C
After adding 140 parts of the novolak type phenolic resin obtained in Production Example 5 to a Whirl mixer, 40 parts of
After kneading for seconds, 21 parts of hexamethylenetetramine was mixed with 10 parts of water.
5 parts (=dissolved and added, kneaded until the resin coated sand disintegrated, then added 7 parts of calcium stearate, mixed for 30 seconds, drained the sand, aerated and made the resin coated sand. I got it.

Comparative Example 2 A resin-coated sand composition was obtained under the same manufacturing conditions as in Comparative Example 1 except that the novolac type phenolic resin obtained in Manufacturing Example 6 was used.

Comparative Example 3 Temperature: 130-140°C (2-heated Sanei No. 6 silica sand 700
After adding 140 parts of the resol type phenolic resin obtained in Preparation 1 and Production Example 7 (2) to a whirl mixer (=Preparation 1), 105 parts of cooling water was added after kneading for 40 seconds, and the resin coated sand collapsed. After kneading, add 7 parts of calcium stearate, mix for 30 seconds, remove sand,
I obtained resin-coated sand by performing Air Lane Four.

Example 1.2.3.4.5.6. and Comparative Example 1.2.
3. Tables 1 and 2 show the characteristic values of each resin-coated sand composition obtained and the disintegration properties of the shell mold.

The test method is as follows.

Bending strength: According to JACT test method 8M-1.

Adhesion point: Depends on JACT test method.

Hot tensile strength 2 JACT test method 5M-10 (according to 2).

Disintegration Resin coated sand with a diameter of 29 mm,
Place in a 150 mm long iron vibrator and pre-fire at 250℃ for 30 minutes. The pipe is coated with aluminum m and treated at 370° C. for 3 hours.

After cooling, take out the pipe and The impact tester shown in Figure 1 (2) Eh, every time (- take out the collapsed sand and measure the amount of remaining sand, and check that the amount of remaining sand is O. Find the number of impacts that resulted in C2.

Figure 1 (2, A is the sample, B represents a part of the hammer.

Part of the hammer is an arm that rotates around a fulcrum C. The fulcrum of part of the hammer is installed at a height of 30 cIn, and part of the hammer is installed horizontally (
= After being lifted, let it fall naturally, and apply an impact to the sample with the fulcrum as the center (d).

[Brief explanation of the drawing]

Figure 1 shows a 118 impact testing machine for testing disintegration properties. A is the sample, B is a part of the hammer, and C is the fulcrum where you can take part of the hammer.

Claims (1)

[Scope of Claims] (1) A resin-coated sand composition in which foundry sand particles are coated with a phenolic resin, and the disintegrability is promoted by the presence of an aromatic nitrate. (2), aromatic nitration is 0-, -) lophenol, p-=-trophenol, m-nitrophenol, 2
．． 4 dinitrophenol, 2.5 dinitrophenol,
2. The resin-coated 9-end composition according to claim 1, which is dinitrophenol and dinitronaphthalene. (3) Phenol resin 1 for blending aromatic nitrates
Special YF which is 0.2 to 40 parts by weight per 00 parts by weight
A resin coated sand composition according to item 1 of the scope of Ni'J requirements. (4) A patent in which phenol 1 is a novolac type phenolic resin! ! The resin coated sand composition according to item 1 or 3 of the desired scope. (5) The resin coated sand composition according to claim 1 or 3, wherein the phenolic resin is a resol type phenolic resin. (6) The resin coated sand composition according to claim 1 or 3, wherein the phenol resin is a mixed resin of a novolac type phenol resin and a resol type phenol resin. (Resin-coated sand composition according to claim 1, 3, 4, 5 or 6, characterized in that the phenolic resin contains a lubricant, (8) ), the introduction of a resin-coated sand grain that coats foundry sand grains with a phenolic resin (2) a resin-coated sand composition in which disintegration is promoted by the presence of an aromatic nitrate; (9) Aromatic nide "1 compound is 0-ditrophenol,
p-nitrophenol, m-nitrophenol, nol, 2
4 dinitrolaenol, 2.5 dinitrophenol, 2
．． 9. The method for producing a resin-coated sand composition according to claim 8, wherein 6D nitrophenol and dinitronaphthalene are used. 1 (Il) of the resin-coated sand composition according to claim 8, wherein the blended amount of the aromatic nitrate is 0.2 to 40 parts by weight per 100 parts by weight of the phenolic resin (2). Method 01), a method for producing a resin-coated sand composition according to claim 8 or 10, wherein the phenolic resin is a novolac type phenolic resin. (+21. Patent where the phenolic resin is a resol type phenolic resin) A method for producing a resin-coated sand composition according to claim 8 or 10. (13) Claim 8, wherein the phenolic resin is a mixed resin of a novolac type phenolic resin and a resol type phenolic resin. A method for producing a resin-coated sand composition according to item 1 or 10. 1. The phenolic resin contains a lubricant.Claims $8, 10, 11, and 12 14. A method for producing a resin-coated sand composition according to item 1 or 13.