JPS6137346A - Coated sand composition having excellent collapsing property - Google Patents

Abstract

PURPOSE:To obtain a compsn. having an excellent low-temp. collapsing property in the stage of producing the coated sand compsn. consisting of sand grains for casting coated with a phenolic resin by incorporating the salt of a specific nitrogenous org. compd. as a collapsing property assistant into said compsn. CONSTITUTION:The hydrochloride and/or hydrobromate of the nitrogenous org. compd. such as >=1 kinds amount an org. amine, melamine resin, urea resin and melamine-urea cocondensation resin which are the collapsing property assistant is incorporated into the coated sand compsn. consisting of the phenolic resin coated with the sand grains for casting in the stage of producing said compsn. The casting mold manufactured by using such coated sand compsn. maintains the prescribed strength during pouring and the collapsing property of the molding sand after casting is good not only in the case of a high pouring temp. but also in the case of producing an Al casting having the low pouring temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to foundry sand used in the production of foundries, and more particularly to a coated sand composition with excellent disintegrability in which the surface of the foundry sand is coated with a resin.

[Conventional technology]

Generally, foundry sand is preferably one that maintains the necessary strength during pouring and has good disintegration properties after casting.

Therefore, phenolic resin is usually used as the binder, and coated sand compositions are used in which the surface of the sand is coated with the resin so that it can maintain a specified strength during pouring. .

However, although such coated sand compositions exhibit relatively good disintegration properties when used with materials such as cast iron, which have a high casting temperature, they do not show sufficient disintegration properties when used with materials such as aluminum, which have a low casting temperature. As a result, there are problems such as removing sand from the casting after casting and removing the core, which is not satisfactory in terms of workability. Therefore, in the foundry manufacturing industry, it is desired to develop coated sand compositions with excellent low-temperature disintegration properties.

[Problem that the invention seeks to solve]

The present invention solves the problems that occur when the coated sand composition as described above is used in the production of aluminum castings at low casting temperatures, such as the time-consuming process of removing sand from the casting and removing the core after casting. This was done to solve the problem.

[Means for solving problems]

The present invention uses organic amines as disintegration aids, melamine resin, urea resin, and melamine-urea cocondensation resin when producing a coated sand composition in which foundry sand grains are coated with phenolic resin. hydrochloride of at least one nitrogen-containing organic compound selected from the group and/or
The present invention relates to a coated sand composition with excellent disintegrability characterized by containing a hydrobromide salt.

〔Example〕

The organic amines used in the present invention have 0 to 15 carbon atoms.
monovalent amine, divalent amine having 1 to 15 carbon atoms, 1 carbon number
-5 trivalent amines and 1c include tetravalent amines having 1 to 6 carbon atoms. These organic amines may be used alone or in combination of two or more.

As the monovalent amine having 0 to 15 carbon atoms, any of primary, secondary, or tertiary monovalent amines can be used, and specific examples thereof include monoethanolamine, jetanolamine, and monoethanolamine. , hydroxylamine, pyridine, morpholine, propylamine, butylamine, hexylamine, diisopropylamine, methylethylamine, trimethylamine, triethylamine, vinylamine, allylamine, amylamine, triallylamine, aniline, 1]roaniline, m-aminephenol, benzyl)amine , toluidine, xylidine and the like, among which monoethanolamine, jetanolamine, triethanolamine, hydroxylamine, pyridine, morpholine or 0-coroaniline are preferred.

Examples of divalent amines having 1 to 15 carbon atoms include 1c, such as ethylene diamine, propylene diamine, 1-rimethylene diamine, tetramethylene diamine, hexamethylene diamine, urea, phenylene diamine, diaminodiphenylmethane, methylene bis Examples include orthochloroaniline, among others, ethylenediamine, hexamethylenediamine or urea are preferred.

As the trivalent amine having 1 to 5 carbon atoms, for example, guanidine, glycocyamine, etc. are preferably used.

As the tetravalent amine having 1 to 6 carbon atoms, for example, hexamethylenetetramine, carbonohydrazide, etc. are preferably used.

There are no particular limitations on the formalin addition rate, viscosity, etc. of the melamine resin, urea resin, or melamine-urea cocondensation resin used in the present invention, and any commonly used commercially available resin may be used.

Specific examples of the melamine resin include Super Beckamine 47-508-60, L-120-60 (manufactured by Dainippon Ink Chemical Co., Ltd.), and Kneepan 203E-60 (manufactured by Dainippon Ink Chemical Co., Ltd.).
Mitsui Toatsu Chemical Co., Ltd.), Sumire Resin 607AC, Sumire Resin 607 Syrup, Sumire Resin 61
Specific examples of urea resins include Beckamine 1800 (manufactured by Dainippon Ink Chemical Co., Ltd.), Kneepan 10R (manufactured by Mitsui Toatsu Chemical Co., Ltd.), and Sumitomo Resin 614 Special (manufactured by Mitsui Toatsu Chemical Co., Ltd.). Examples of melamine-urea cocondensation resins include Super Beckamine 0O-L-131-60 (manufactured by Dainippon Ink Chemical Industry ■) and Kneepan 134 (manufactured by Mitsui Toatsu Chemical Industry ■). can.

In the present invention, the above organic amines, melamine resins, urea resins, and melamine-urea cocondensation resins are all used in the form of hydrochlorides or hydrobromides. By using these salts, the object of the present invention can be achieved.

The neutralization rate of organic amines is closely related to the disintegrability of the mold formed from the resulting 21-ted sand composition, and is determined as appropriate depending on the purpose, but is usually 30 to 130.
Preferably it is mol%.

In the case of melamine resins, urea resins, and melamine-urea cocondensation resins, it is preferably 2 to 50% (by weight, hereinafter the same) based on the solid content, and more preferably 5 to 50%. Good.

Hydrochloride and/or odor of at least one nitrogen-containing organic compound selected from the group consisting of organic amines, melamine resins, urea resins, and melamine-urea cocondensation resins, which are disintegration aids used in the present invention. The amount of hydrochloride to be used is usually 0.1 to 40%, preferably 3 to 15%, based on the amount of phenol resin used. If the amount used is less than 0.1%, it is not preferable because the disintegration properties of the mold formed from the obtained coated sand composition will decrease.
On the other hand, if it exceeds 40%, the disintegrability may be satisfactory, but the strength required during pouring tends to decrease, which is undesirable.

There are no particular limitations on the phenolic resin used in the present invention,
Any phenolic resin used in the production of coated sand compositions known in the art may be used. For example, in the presence of one or more phenols such as phenol, cresol, xylenol, butylphenol, ocdylphenol, resorcinol, catechol, and bisphenol A, and an acidic catalyst such as hydrochloric acid, oxalic acid, and organic sulfonic acids. Examples include, but are not limited to, those obtained by adjusting the ratio of formaldehyde and phenols to 0.3 to 1.0:1.0 by molar exchange and reacting under heating. .

The coated sand composition of the present invention is obtained by adding 0.5 to 5% of a composition containing the above-mentioned phenolic resin and disintegration aid to the foundry sand grains to coat the sand grains. A lubricant, a curing accelerator, etc. may be added to the phenol resin composition as necessary.

Examples of the lubricant include waxes such as carnauba wax, paraffin wax, and polyethylene wax; and fatty acid amides such as methylene bisstearamide and ethylene bisstearamide. The amount of these lubricants to be used is selected in consideration of the wettability of the phenolic resin composition to foundry sand grains and the speed of curing, and is usually preferably 0.5 to 5% based on the phenol resin.

Organic acids such as aromatic acid or salts made of organic acids and organic amines can be used.

The amount of the curing accelerator to be used is usually 0.5 to 5% based on the novolac type phenol resin.

In the present invention, disintegration aids, lubricants, hardening accelerators, etc. are added to the phenolic resin, but there are no particular restrictions on the method or time of addition of each component, and these are melted into the phenolic resin. A method such as mixing or mixing at the time of preparing resin-coated sand may be adopted as appropriate.

The composition for producing a coated sand composition thus obtained is added to sand together with a hardening agent, hexamethylenetetramine, and other anti-blocking additives, such as calcium stearate.
The mixture is heated to about 170° C. and mixed until uniform, thereby preparing resin-coated sand, which is a dead sand composition.

The coated sand composition thus produced is used for producing various molds.

The mold manufactured using the coated sand composition of the present invention maintains a predetermined strength of about 30 to 40K (+/Cl112) during pouring, and has a casting temperature of 100K.
The collapsibility of the molding sand after casting is sufficiently good not only in the production of cast iron with a high temperature of 0 to 1500℃, but also in the case of aluminum castings where the casting temperature is as low as 500 to 800℃. This makes it easy to remove sand from castings and remove the core, making it satisfactory in terms of workability.

The coated sand composition of the present invention will be explained in detail below with reference to production examples and examples, but the present invention is not limited thereto.

Production Example 1 250 parts of hexamethylene diamine (parts by weight, the same applies hereinafter)
After stirring and dissolving 120 parts of water, 431 parts of 36% hydrochloric acid was gradually added under cooling to obtain an aqueous solution of hexamethylene diamine hydrochloride having a solid concentration of 50%.

Production Example 2 160 parts of melamine resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: violet resin 601 syrup) with a solid content of 50% a degree and 374 parts of warm water were mixed, stirred and dissolved, and then added with 36% hydrochloric acid while cooling. 20.7 parts (equivalent to 9.3% based on the solid content of the melamine resin) were gradually added to obtain an aqueous solution of melamine resin hydrochloride having a solid content of 11 degrees and 40%.

Production Example 3 60 parts of urea and 162 parts of 37% formalin were placed in a flask, and then caustic soda was added to adjust the pH to 137.5. Next, the temperature was raised to a running temperature, and after refluxing the inside of the flask for 5 minutes, 0.26 part of Gi@ was added, and rapid flow was continued for another 2 hours. Add 1 part of 36% hydrochloric acid to this
0.5 part (equivalent to 3% based on the urea resin) was added to obtain an aqueous solution of urea resin hydrochloride with a solid content concentration of 38%.

Example 1 A resin composition was obtained by melt-kneading 100 parts of a novolac type phenol resin (carbonic acid based using an oxalic acid catalyst, resin softening point: 95°C) and 2.5 parts of ethylene bisstearamide. Then, silica sand 1 preheated to 150℃
Add 1.4 parts of the above resin composition to 00 parts, stir for 1 minute with a mixer, and add 330.2 parts of hexamethylene diamine hydrochloric acid with a concentration of 50% obtained in Production Example 1 to the rough. and kneaded for 5 seconds. Thereafter, 0.7 part of a 30% concentration hexamethylenetetramine aqueous solution was added and kneaded for 1 minute, and 0.1 part of calcium stearate was added and kneaded for 20 seconds to prepare a coated sand composition.

The melting point, transverse rupture strength and disintegration properties of the obtained coated sand composition were measured according to the following measuring methods. The results are shown in Table 1.

(Yushubi Onmaro) According to JACT test method 〇-'1.

(transverse rupture strength) According to JACT test method 5H-1.

(Disintegratability) Diameter 22IIllI11 heated to 250℃ in advance
Fold it lengthwise, let it cool, then wrap both ends with aluminum foil. This is placed in an iron cylinder with a diameter of 85 mm and a length of 200+++ m with a lid on one side, and the surrounding area is filled with sand. This was heated to 600℃, 90℃
Remove after heating for a minute. After cooling, the iron pipe is subjected to an impact using an impact tester, and after each impact, the collapsed sand is taken out and the amount of remaining sand is measured, and the number of times of impact until the amount of remaining sand becomes zero is measured.

Examples 2 to 15 and Comparative Examples 1 to 5 The disintegration aid used in Example 1 and its usage amount were
A Ted sand composition was prepared in the same manner as in Example 1, except for the changes shown in the table, and its properties were measured. The results are shown in Table 1.

Note that the melanin resin in Table 1 is violet resin 607.
The syrup and urea resin are the same as those prepared in Production Example 3.

Blank space below [Effects of the Invention] The mold manufactured using the coated sand composition of the present invention maintains a predetermined strength during pouring, and
Not only in the case of manufacturing cast iron where the casting temperature is high,
Even when manufacturing aluminum castings with low casting temperatures, the disintegration properties of the molding sand after casting are sufficiently good, making it easy to remove sand from the castings and extracting the core, making it satisfactory in terms of workability. This is Shiuruchino.

Claims (1)

[Scope of Claims] 1. When producing a coated sand composition in which foundry sand grains are coated with a phenolic resin, a compound selected from the group consisting of organic amines, melamine resins, urea resins, and melamine-urea cocondensation resins is used. A coated sand composition having excellent disintegrability, characterized in that it contains a hydrochloride and/or hydrobromide of at least one nitrogen-containing organic compound. 2. The organic amine is at least selected from monovalent amines having 0 to 15 carbon atoms, divalent amines having 1 to 15 carbon atoms, trivalent amines having 1 to 5 carbon atoms, and tetravalent amines having 1 to 6 carbon atoms. The composition according to claim 1, which is one type. 3. The composition according to claim 2, wherein the monovalent amine having 0 to 15 carbon atoms is monoethanolamine, diethanolamine, triethanolamine, hydroxylamine, pyridine, morpholine, or O-chloroaniline. 4. The composition according to claim 2, wherein the divalent amine having 1 to 15 carbon atoms is ethylenediamine, hexamethylenediamine or urea. 5. The composition according to claim 2, wherein the trivalent amine having 1 to 5 carbon atoms is guanidine or glycocyamine. 6. The composition according to claim 2, wherein the tetravalent amine having 1 to 6 carbon atoms is hexamethylenetetramine or carbonohydrazide.